Transmission questions on 93 500E

[oaklandw124]

I am the proud new owner of Maui's first 500E. I will start a new owner thread soon, but had a couple of questions about how the car is shifting.

The car has a FGS installed and it is activated by moving the child safety window switch. Some observations when the FGS is activated:

From standing start, at WOT car will not shift from 1-2...engine hits the rev limiter and wont shift until I reduce acceleration somewhere around 5000-5200 rpm.

With FGS deactivated, I observe the following:

Car will shift fro 2-3 ok, but has a flare or pause to it. this is exaggerated at higher rpm's. Have not taken it to 6000 rpm from 3-4 as I don't want to go to jail

Car will not shift from 3-4 until 3000 rpm, no matter if it is a gentle acceleration or a hard acceleration. This is a little annoying at speeds around 40-50 mph as the rpm's sit around 2900 in 3rd gear.

Do you think the kick down switch could be causing this? I'm also wondering if the shop who installed the FGS maybe messed with the shifting points.

At what rpm does a 500E normally shift at for each gear? I'm guessing what I'm experiencing isn't normal, especially the no shift from 1-2, but wanted to get the board's opinion.

Thank you in advance...it is a great car! Gives my Porsche 928GTS a run for it's money!

 

[KarlC]

I am the proud new owner of Maui's first 500E. I will start a new owner thread soon, but had a couple of questions about how the car is shifting.

...it is a great car! Gives my Porsche 928GTS a run for it's money!

Congratz, if you think its great now wait until you get the FGS and Tranz issues worked out.

Looking forward to your Owners thread.

 

[Glen]

It sounds like someone has messed with the bowden cable and/or modulator pressure to mask the 2-3 flaring. You should get some opinions shortly but until then, deactivate FGS, from a stop, move the shift lever to 'B' for a couple seconds and then back to 'D'. Launch aggressively and note if the car starts in 1st gear. If you can, try this with the pedal all the way to the floor and note each gear change for characteristics and what RPM. This will give us a better idea of what the trans is doing.

 

[gsxr]

At what rpm does a 500E normally shift at for each gear?

At full throttle, with kickdown switch clicked, it should upshift at indicated 6000rpm (±100rpm or so).

At part throttle, the upshift RPM will vary proportionally with throttle position.

 

[gerryvz]

At what rpm does a 500E normally shift at for each gear? I'm guessing what I'm experiencing isn't normal, especially the no shift from 1-2, but wanted to get the board's opinion.

This totally depends on a number of factors -- including the gas pedal position, RPMs, etc. In normal driving the car shouldn't shift much above 3,000 RPM. At maximum acceleration it should upshift at or just above 6,000 RPM -- at or just after redline.

Depressing the gas pedal all the way down to activate the kickdown switch should result in a near-immediate downshift (generally this is one gear down, but can be two depending on factors involved). On the .036 transmission it's not instant, takes a second to go down. Of course, you can also use the lever to manually downshift and do it yourself.

I would also try adjusting the transmission to see whether the flaring can be adjusted out, and if the shift timing via the Bowden cable can be tweaked. From my own experience adjusting the Bowden cable (shift timing) on my wife's E320 wagon, with the new transmission installed, I can tell you that even a turn or two of the adjuster screw can have a SIGNIFICANT effect on shift timing. And the same thing with the modulator adjustment -- you only want to do that 1/4 turn or LESS each adjustment, and see where you're at before trying to adjust again.

I think Glen is right -- someone messed around with the adjustments in an attempt to try to make it as smooth and non-flaring as possible. There are always compromises though.

You can test the kickdown switch just by flooring it and you should be able to feel the click of it activating under the pedal.

Same thing with FGS - you can and should use the gear lever to move it to "B" and back, to see if you can force it into first gear.

I think I would start with the shift timing (Bowden cable) and get that correct, and then work the modulator to actually sharpen or soften the actual shifting characteristics. Do know that these mechanical automatic transmissions will NEVER shift as softly as a modern electronically controlled automatic. You will generally always feel the up or downshift on an .036 or other 722.3 automatic transmission. It should NEVER be harsh or jerky, but you will generally always feel the shift to varying degrees (depending on up or down shift, 2-3 or 3-4, RPM, speed of the car, etc.).

Good luck with this. You may well need to consider a rebuild if the characteristics can't be adjusted and there is significant flaring. How is the reverse engagement? Long delay (more than 1.5-2 seconds?) or is it good? Clicking in reverse?

Cheers,
Gerry

 

[gsxr]

FYI: Flaring at 2-3 upshift is a separate issue from the other problems described. The 2-3 slare is a pretty common issue on higher-mile 722 transmissions. There are a number of possible fixes, including adjusting modulator pressure (which will affect shift firmness on ALL upshifts), changing the K2 spring with the factory upgrade (which doesn't do much), or trying the Superior shift kit K2 springs (which are much stronger than the factory springs), along with avoiding thinner Dex-VI fluids, or trying "alternate" fluids (last ditch effort before rebuild, IMO).

The flare issue should really be a separate thread. Your main problem at the moment seems to be related to the electronic FGS widget. Get it shifting at the proper RPM's first, then worry about shift firmness afterwards.

 

[Roma_500E]

I am the proud new owner of Maui's first 500E. I will start a new owner thread soon, but had a couple of questions about how the car is shifting.

The car has a FGS installed and it is activated by moving the child safety window switch. Some observations when the FGS is activated:

From standing start, at WOT car will not shift from 1-2...engine hits the rev limiter and wont shift until I reduce acceleration somewhere around 5000-5200 rpm.

With FGS deactivated, I observe the following:

Car will shift fro 2-3 ok, but has a flare or pause to it. this is exaggerated at higher rpm's. Have not taken it to 6000 rpm from 3-4 as I don't want to go to jail

Car will not shift from 3-4 until 3000 rpm, no matter if it is a gentle acceleration or a hard acceleration. This is a little annoying at speeds around 40-50 mph as the rpm's sit around 2900 in 3rd gear.

Do you think the kick down switch could be causing this? I'm also wondering if the shop who installed the FGS maybe messed with the shifting points.

At what rpm does a 500E normally shift at for each gear? I'm guessing what I'm experiencing isn't normal, especially the no shift from 1-2, but wanted to get the board's opinion.

Thank you in advance...it is a great car! Gives my Porsche 928GTS a run for it's money!

I had 90% similar symptoms like you described with my transmission (FGS valve body installed) and now I have a brand new transmission. In my case and experience all these signs were caused by normal but excessive wear on tranny . Simply it was time to rebuild or replace it.

You also might have a delay in reverse too which is another sign of worn tranny.

In addition if your fluid is clean and you still experiencing these problems then most likely your tranny will be gone sooner or later (depends on your patience).

2-3 issue, adjusting modulator is only temporary solution and your tranny will be acting weird.

Check your fluid and make sure all cables adjusted right (I checked them tons of times in a hope of simple repair but ....).

In case you will end up replacing tranny , I would strongly suggest you to go with the brand new from dealer unless you have/know/find EXTREMELY good re-builder. Not sure if my new tranny was rebuilt but it says Made in Germany on box and tranny itself has tags and metal badge on German. Dealer said it came from Germany.

The reason I went with the dealer tranny is that I wasted tons of time calling rebuilders, some of them forgot to call me back so I had to call them and remind that I want to bring nice car and $4000 cash. I also wasted OE filters and about 16 quarts of Redline fluid trying to bring back to life worn tranny. It was a long path to me when I finally realized the best and right way to fix my beauty. Although dealer is stealer but they are hassle free if you need something to be done when you want it to be done.

initially super clean proper fluid
1-2 not shifting (hits rev but does not shift until you reduce acceleration)
2-3 delay, eventually slipping
3-4 delay, eventually slipping
down shift but does not go to gear (hits rev)
reverse delay


All these are 100% signs of WORN tranny


I would suggest you to check tranny if it is worn or not .

Let us know what you find out with your tranny.

 

[oaklandw124]

Thanks, everyone. I will try to answer the various questions the best that I can.

First of all, Maui had the fluid changed at his local shop about 2000 miles ago, and fluid level looks good. Non-synthetic was used as he was charged only $5 per quart.

Trans shifts fine into reverse. No clicking and about 1 second to engage. I tried this several times from both P to R, then D to R.

I have spoken to Marc at Sun Valley Transmissions after I saw Gerry's post about them. Marc has given me a list of items to check, centering around the kickdown switch solenoid (I guess there is a rubber o-ring on the switch solenoid that he said gets harder with age and that might be the cause of the 3-4 upshift at only 3000+ rpm. He also told me I could send him my trans in the winter and $2k later he will send me mine all rebuilt. How does that compare to the cost of a new trans from the dealer?

Kickdown switch seems to work fine. If I am in 4 and floor it, I get an immediate downshift into 3rd.

It seems like the shift from 3-4 at a higher rate of acceleration is what I would expect the trans to shift like. the 2-3 shift is what makes me feel uneasy about the trans.

Is it possible the FGS setup in the car can prevent the gear level from going into B? Mine doesn't want to go into that slot.

What would cause no 1-2 shift at 6000rpm?

 

[Roma_500E]

Thanks, everyone. I will try to answer the various questions the best that I can.

First of all, Maui had the fluid changed at his local shop about 2000 miles ago, and fluid level looks good. Non-synthetic was used as he was charged only $5 per quart.

If it is proper Dexron III fluid then fluid is not a problem. Your last chance is cables. If not, get a tranny or rebuild.

Trans shifts fine into reverse. No clicking and about 1 second to engage. I tried this several times from both P to R, then D to R.

Ideally it should be immediate engagement, at least this is how reverse works on my new tranny. As far as I understand any delay means worn clutches. More delay more worn clutches.

I have spoken to Marc at Sun Valley Transmissions after I saw Gerry's post about them. Marc has given me a list of items to check, centering around the kickdown switch (I guess there is a rubber o-ring on the switch that he said gets harder with age and that might be the cause of the 3-4 upshift at only 3000+ rpm. He also told me I could send him my trans in the winter and $2k later he will send me mine all rebuilt.

Do not know about rebuild tranny but tranny I bought had all new OE cables, sensors and linkages on it. Some of them alone cost some $$.

How does that compare to the cost of a new trans from the dealer?

I cannot recall exactly how much I paid but I believe it was something around $4000+ tranny and labor , and $1600+ for the torque converter. Please double check numbers in my thread about my personal experience/feeling with the new tranny. I do have a good discount at MB dealer too. I bought tranny in 2013 . At the beginning of 2014 price (MRSP price at parts.com) was dropped by $600 for some reason. However, I check in April 2014 price (MRSP price at parts.com) again and it seems it went up by $1000 compare to the beginning of 2014. So nit sure about current price.

the 2-3 shift is what makes me feel uneasy about the trans.

This is one of the popular signs of worn tranny . I spent quite a bit time doing a research on tranny and I found lots people reporting this issue. Also I believe Dave confirmed that this means worn tranny.

What would cause no 1-2 shift at 6000rpm?

Do not know exactly what causes it but in my case it was worn tranny .

P.S. If you want to enjoy your 500E do not put up with jerky tranny. Get a new one and you will not regret. When I got my new tranny the only thing I regret was that I did not do it earlier.

 

[Glen]

You have some flavor of electronic FGS so, no, it is not preventing you from engaging the 'B' switch. It's a pretty firm click into 'B', it doesn't just flop over, so you might not be using enough force. If you can't get it into 'B', then you may have a physical obstruction...if so, you will need to remove the wood trim and have a look.

You are probably aware that your S4 uses basically the same transmission, so if you have a trusted mechanic for your 928, they may be able to help you diagnose your trans issues.

 

[Maui]

Eric,

Part of the FGS module extends into the shift gate which does not allow the shifter to be placed into the B position. I have no idea what brand the FGS module is but I think it was installed by the local shop there in your neighborhood. I would take the car in there just to get the run down on the FGS system if nothing else.

 

[gsxr]

Kickdown switch seems to work fine. If I am in 4 and floor it, I get an immediate downshift into 3rd.

This will happen even if the kickdown switch or solenoid is disconnected or not working, it is due to the Bowden cable function. You don't always need 100% throttle to get a kickdown (this is based on vehicle speed & current gear).

Is it possible the FGS setup in the car can prevent the gear level from going into B? Mine doesn't want to go into that slot.

No, the shift lever should always move through all positions, including the B position. Sounds like a shift linkage alignment issue, or a problem with the B switch inside the shifter assembly.

What would cause no 1-2 shift at 6000rpm?

Pretty much the only thing that would cause this is constant +12v at the kickdown solenoid, from a FGS problem, or B-switch problem.

 

[Glen]

Like I alluded to above, you need to disengage your FGS system. Eliminate that variable while troubleshooting.

Pretty much the only thing that would cause this is constant +12v at the kickdown solenoid, from a FGS problem, or B-switch problem.

 

[gsxr]

Like I alluded to above, you need to disengage your FGS system. Eliminate that variable while troubleshooting.

YES! Sorry, I thought the FGS was already disconnected for troubleshooting. That's step #1.

 

[oaklandw124]

Ok, just went out for a test drive. I was able to get the gear lever to B. Here is what happened:

When in B, accelerating and putting into position 2, car would not shift into gear, just stayed in 1st at high rpm. only when I moved gear lever to 3 did it shift.

When in 2 and accelerating, putting it into position 3 produced the same flare that i get when shift lever in is D and I accelerate hard.

So, the B-2 is not good, right? Is there anything to check, other than my bank balance?

 

[gsxr]

Eric, have you disabled (preferably, physically disconnected) the FGS module? That MUST be done before any other troubleshooting.

Shift lever position has zero effect on shift firmness, btw. Shift firmness is entirely based on the engine vacuum signal (which is load dependent) sent to the vacuum modulator, along with the modulator adjustment.

 

[Roma_500E]

 

[oaklandw124]

Spoke to Marc at Sun Valley and he is asking me to put a test light at the kick down solenoid to see if it is activating when in the B position. He also mentioned the little screen in the governor valve body could be obstructed.

Dave, haven't physically disabled the FGS as I'm not sure how to go about removing it. Would love to get that thing out of there, though.

 

[gsxr]

Dave, haven't physically disabled the FGS as I'm not sure how to go about removing it. Would love to get that thing out of there, though.

You have to find the control box and unplug it. Check in the center console rolltop box, and behind the trans tunnel carpet. Worst case, remove the shift console wood and find the non-stock wiring at the B-switch (should be easy to see) and trace where it goes.

Side note: These cars get the +12v source for the kickdown solenoid from the LH module, the ignition must be turned on in order to do any testing. And, I'm not 100% certain if you can test without the engine running... never tried.

 

[oaklandw124]

Eric,

Part of the FGS module extends into the shift gate which does not allow the shifter to be placed into the B position. I have no idea what brand the FGS module is but I think it was installed by the local shop there in your neighborhood. I would take the car in there just to get the run down on the FGS system if nothing else.

Thanks, Ken. I was able to get the shifter into position B. Unfortunately, the shop that did most of the work on the car did not install the FGS and they do not know what type was installed. I will try to trace the wiring and see if I can find where the control box is.

 

[oaklandw124]

You have to find the control box and unplug it. Check in the center console rolltop box, and behind the trans tunnel carpet. Worst case, remove the shift console wood and find the non-stock wiring at the B-switch (should be easy to see) and trace where it goes.

Side note: These cars get the +12v source for the kickdown solenoid from the LH module, the ignition must be turned on in order to do any testing. And, I'm not 100% certain if you can test without the engine running... never tried.

Will do, Dave. I guess I'm going to learn a lot about transmissions fairly quick. Regarding the testing, I think Marc wanted the test light at the kick down solenoid so I could see if the circuit is correctly giving power to the switch at the correct time. Since I will be driving the car with test light installed, power will be supplied.

 

[Maui]

Thanks, Ken. I was able to get the shifter into position B. Unfortunately, the shop that did most of the work on the car did not install the FGS and they do not know what type was installed. I will try to trace the wiring and see if I can find where the control box is.

It looked to me that the shifter would not go into the B position, so I never tried. There is a coax wire in the engine compartment next to the main fuse box. I don't know if disconnecting that wire will disable the FGS.

 

[gerryvz]

The FGSSwitch FGS system uses Coax cable. It is probably located along the side of the transmission tunnel below the radio area or further aft.

 

[gsxr]

The FGSSwitch FGS system uses Coax cable. It is probably located along the side of the transmission tunnel below the radio area or further aft.

+1... I think Gerry is correct. Very likely a "FGSswitch" setup (click here), not a BergWerks FGS, which is totally different.

 

[Klink]

As usual, I'm late to this party and may have missed something. Full disclosure: I don't have any experience with these aftermarket full time first gear take off devices, as I wouldn't have the slightest interest in them. 99% of the time, I like 2nd gear starts, and for the rest of the time a first gear start is as close as my right hand, so I never understood this particular fetish. All of these "3 speed with underdrive" transmissions have a simple manual work around for first gear, even at low load, so again I don't get it. (Yes, "3 speed with underdrive" is a Klink patented phrase, but blanket permission has been granted to anyone else that may like to use it)

That being said, I have to assume that most of these devices work by engaging and then quickly releasing the kickdown solenoid just as the vehicle is moving off. If the solenoid is left engaged, such as by one of these devices leaving power to the solenoid for a longer or indefinite period of time after take off, one will get pretty much exactly the erratic shifting described above. So yes one should indeed disable these devices for initial diagnosis.

But if that's difficult to do, consider the following first:

If it is difficult to move the shifter into the last detent and / or push it into the "B" position, this indicates the possibility that the fork shaped lever that actuates the "B" position switch in the shift gate has inadvertently been shifted into the "B" position independent of the shift lever. Look into the rearmost part of the shift gate carefully. If you find this is the case, simply use an appropriate tool to shift the fork back into the center of the gate. It should be waiting there to "receive" the shift lever as it is pulled rearwards, not already moved sideways blocking the lever. Moving this switch lever over was a common workshop prank back in the day, and somehow customers occasionally manage to displace it as well. This is also much more common with the shape and /or diameter of some aftermarket shift levers.

Also check for a stuck or displaced kickdown switch. It is mounted in the floor under the gas pedal (E-gas pedal?). These switches often stick in the depressed condition and this also results in a condition similar to what has been described. They can also be displaced from the mounting bracket and jammed. Sometimes the carpet mat will be too tight on them and not allow them to fully release.

Check for these conditions first, because it only takes minutes. These conditions are easier to check and rule out then either disabling your FGS or getting underneath things to do a proper test for inappropriate powering on of your kickdown solenoid. Every other suggestion up there is a good one and may prove necessary. After all, test is not a four letter word. But almost every car with this type of transmission control system exhibiting these symptoms, sometimes even including a dramatic 2-3 flare, has a stuck kickdown switch, and / or a stuck "B" position switch.

Good Luck!
Klink

 

[clarkz71]

I belive the FGS switch is defective.

My 034, which as most of you know has a FGS valve body.

If I use full throttle in D, the trans shifts right @ 6000

If I use the B position it will hit the rev limiter.

My transmission is a factory Mercedes reman

When I use B, I shift to 2 @ redline and the shift is @ 6300 rpm which is perfect as it "feels" like it's still pulling hard.

My rev limiter is 6500 rpm

Maybe Dave can try this with his 034 or some other member.

I personally like this but the OP's car should not do this in D, 3, or 2 as mine does not.

 

[oaklandw124]

Just an update. I had a little time to look at the car over the weekend. I focused on the coax cable that runs along the fuse panel in the engine compartment. I don't think that cable is associated with the FGS module. Although it is coax, with a BNC T connector, it looks factory as one end of the cable runs into the fuse panel. Plus, when I pulled the cable apart, my ASR and ABS lights came on in the dash. So, looks like I need to focus on the center console. Is it difficult removing the wood trim?

 

[gsxr]

Just an update. I had a little time to look at the car over the weekend. I focused on the coax cable that runs along the fuse panel in the engine compartment. I don't think that cable is associated with the FGS module. Although it is coax, with a BNC T connector, it looks factory as one end of the cable runs into the fuse panel. Plus, when I pulled the cable apart, my ASR and ABS lights came on in the dash.

There are no visible "T" connectors in the factory coax wiring. Click here: http://fgsswitch.com/Ex_install/500e.html

This is the factory wheel speed connector (right side, round thingy) :

This is the FGS "T" spliced into the factory coaxial wire:

This is the FGS module:

So, looks like I need to focus on the center console. Is it difficult removing the wood trim?

No, but be careful not to force anything... replacing or refinishing wood is expensive. There should be some DIY / How-To articles on some of the MB forums showing how to remove everything. I'd probably start by pulling the trans tunnel carpet on the driver's side, and/or lowering the trim panel below the steering column, pretty likely the module will be in that area... but you never know.

 

[sheward]

Is it difficult removing the wood trim?

No. Remove the 1 or 2 Phillips screws inside the roll top box and remove the box. This reveals 2 screws holding the wood panel. Once these are removed the panel lifts off, starting at the rear. It does take a scary amount of force to lift the panel as there are many plastic "hooks" around the switches underneath and the plastic has no doubt become harder with age. I dressed these with a file to make removal easier in the future.

drew

 

[Maui]

Fold the armrest to the upright position and then open the sliding tray on the lower compartment just below the armrest. There are two philips screws at the front inside of the tray. They are slanted slightly which makes they easy to get a screw driver on them. Once that is off you will see a philips at the very back of the wood console piece that you will also remove. As you lift the wood console gently press the seat heater switches inward with your thumb as they will not come out with the console and will stay with the car. The mirror switch will stay with the console cover it has several prongs that plug in, but I can't remember if the window switches need to be pressed out or come out with the console. The switches click into place with out too much effort. It's not too difficult to get the console out but care should be exercised as not to break anything. The wood on this car has no cracks. You also will want to remove the V8 shift knob. Just unscrew the grommet below the shift knob and the knob will lift off with some twisting and pulling. Which is actually nice because if it had the stock shifter it would difficult to get the console wood off and out of the way. If I remember correctly there are a couple phillips screws holding the plastic piece below the wood console cover. If you need to remove the shift gate piece be very careful as the tabs that hold it down can be broken. I know because I had to replace it once. There are tabs on the left and front that hold it into position. I've had the console out a couple of times but never dug any deeper then I needed to to install the shifter. Take your time and be patient with it.

When you put things back together make sure the lower tray below the armrest is positioned correctly and the two scores are secure. It make take some adjustment to get it perfectly straight. Otherwise the arm rest and console will squeak and drive you crazy.

 

[oaklandw124]

Thanks, guys! Appreciate the in depth instructions.

And DAve, thank you for the pics of the FGS in relation to the stock items in the car. One question, can't I just disconnect the FGS at that BNC connector? Or do I need to disconnect it from the module somewhere under the console.

 

[Maui]

Some good info on 2phast's website. http://www.2phast.com/500e/default.htm

From fgs website: http://www.fgsswitch.com/Ex_install/500e.html

 

[gsxr]

And Dave, thank you for the pics of the FGS in relation to the stock items in the car. One question, can't I just disconnect the FGS at that BNC connector? Or do I need to disconnect it from the module somewhere under the console.

I'm not 100% certain how this particular FGS works, but you can try disconnecting the coax cable at the BNC "T" connector, and see if that disables the system. I'm not sure what it does with no speed signal.

My FGS is BergWerks, which uses the Hall speed signal available inside the car, no coax splicing involved... totally different system.

 

[oaklandw124]

Hi all, thought I would update this thread since last week. Still haven't had the time to look for the FGS module, but I discovered another interesting trait the car has and thought it might be transmission related. When I first start the engine, the car wants to move forward just a little bit. It does the same thing if I am in neutral or park and hit the throttle quickly...the car moves forward just a little bit. When I get under the car, I can physically see the drive shaft move. Is this normal for the 500E? I have an 1997 S500 and it doesn't do this.

 

[Klink]

Hi all, thought I would update this thread since last week. Still haven't had the time to look for the FGS module, but I discovered another interesting trait the car has and thought it might be transmission related. When I first start the engine, the car wants to move forward just a little bit. It does the same thing if I am in neutral or park and hit the throttle quickly...the car moves forward just a little bit. When I get under the car, I can physically see the drive shaft move. Is this normal for the 500E? I have an 1997 S500 and it doesn't do this.

WOW, 3 of my absolute all time favorites: 5 liter 140, E500E, 928!!! A Porsche actually made correctly!!! Just like some of my favorite Benzes, I love it despite it being a fall apart fright pig...)

Some of that is normal when they are cold and the fluid is thick. Just caused by the friction of the thick oil in the clutches, etc. However, if it is really pronounced, like you can actually "drive" the car on level ground in neutral, than something is definitely broken. If it just surges forward a tiny bit it is OK. Any shattering or grinding noises in any selector lever position will require attention. Most of the things that can break or malfunction to cause this will also do it to the same level when the transmission is hot. Not likely representative of a problem, at least not from here over the phone...

 

[oaklandw124]

I saw on the FGSswitch.com website that the default setting for the module was for tire size 215/65/15. Since my tires are 18", could this be the cause of the transmission issues I am experiencing?

 

[Klink]

I saw on the FGSswitch.com website that the default setting for the module was for tire size 215/65/15. Since my tires are 18", could this be the cause of the transmission issues I am experiencing?

Extremely unlikely. That is about the same effective diameter of any 18 that you are likely to be using. For you inquiring minds out there wondering what MB used that tire size, it was later 126 5.6 liter cars in the ECE...

 

[oaklandw124]

Ok, had some time to remove the carpet panels around the console to see if I could find the FGS module. No luck. I did see three wires (red/blue/black) that went into this little box(picture #1). Since it didn't have a port for the BNC cable, I'm thinking this isn't it.

I did find a little toggle switch under the knee bolster panel on the driver's side(picture #2).

And I did find a cable with a BNC connector, but it wasn't hooked up to anything(picture #3).

So, not sure where else this module could be. I would have thought the BNC cable would have led me to it. Or, maybe it is a different module than the FGSmodule.com product?

 

[gsxr]

Eric, is there any MB part number on the unknown black box? That almost looks like the factory FGS relay from a 126 chassis...

 

[Christian_K]

Eric, is there any MB part number on the unknown black box? That almost looks like the factory FGS relay from a 126 chassis...

Wow i wasn't aware the 126s got something like that. Is that everywhere or was it just in the US?
What about a retrofit into a 500E? Worth it?

 

[Klink]

Eric: If you can, post some photos of the mystery module. One photo of each side would be great. If there's any kind of label or writing on it, a clear rendition of that would be great, too. If you can, also show as much as you can regarding the wiring. What wires dose it connect to? Colors? Locations, photos of same? Anything may help. You could also just unplug the mystery module and see what happens. It isn't likely that something irreversible and bad will occur... On that subject, have you disconnected the kickdown solenoid at the rear right side of the transmission followed by a test drive? If you've already done that, sorry, I missed it. That would be the best test you could do. If you do that and the symptoms remain, then we are barking up a very wrong tree focusing our attention here. Also, re-read and comment on post #25 if you don't mind. It Won't hurt my feelings if you don't but there was some useful information there.

 

[Klink]

Wow i wasn't aware the 126s got something like that. Is that everywhere or was it just in the US?
What about a retrofit into a 500E? Worth it?

Early (pre late '85 facelift) 126 5 liter cars had second gear take off. They used an fgs box like that to produce the first gear start via the shifter. It had a function similar to the aftermarket FGS boxes, except that it wasn't full time fgs unless one rigged it to do so.

 

[captruff]

I have a few of those black boxes....let me go find them and post up the pictures. This has been used by Tom aka infoage to allow for FGS on his 500E. I plan to eventually do the same using the factory e/s switch next to the gear selector lever.

Jeff

 

[gsxr]

Early (pre late '85 facelift) 126 5 liter cars had second gear take off. They used an fgs box like that to produce the first gear start via the shifter. It had a function similar to the aftermarket FGS boxes, except that it wasn't full time fgs unless one rigged it to do so.

Correct - and it has a fixed upshift point (around 7mph, IIRC). EPC seems to indicate it was only used on a couple of years in the USA.

 

[oaklandw124]

Here are some more pics. I also took a pic of the kickdown switch. I think this is stuck in the depressed position because i can't press it down and it wont pop back up. So, maybe I need to disable from the trans as I haven't done that yet (sorry Klink for not mentioning this earlier when you said it in #25. So, this is on the right rear(passenger) side of the trans, correct?

So, for the mystery box, if it is a W126 version, can I just unplug it? There are blue/red/brown wires coming out of the plug. The brown wire is spliced to a black wire that runs over the top of the shift gate and goes toward the radio. The red and blue wires run along the left side of the shiftgate and disappear somewhere around the bottom of the shiftgate towards the child window switch or the B in the shiftgate. What's interesting is that the car has the coaxial/BNC t connection in the engine compartment by the driver side firewall that Dave had in his thread above. If that is in the car, shouldn't there be the FGSmodule.com module that people thought was there?

 

[oaklandw124]

As usual, I'm late to this party and may have missed something. Full disclosure: I don't have any experience with these aftermarket full time first gear take off devices, as I wouldn't have the slightest interest in them. 99% of the time, I like 2nd gear starts, and for the rest of the time a first gear start is as close as my right hand, so I never understood this particular fetish. All of these "3 speed with underdrive" transmissions have a simple manual work around for first gear, even at low load, so again I don't get it. (Yes, "3 speed with underdrive" is a Klink patented phrase, but blanket permission has been granted to anyone else that may like to use it)

That being said, I have to assume that most of these devices work by engaging and then quickly releasing the kickdown solenoid just as the vehicle is moving off. If the solenoid is left engaged, such as by one of these devices leaving power to the solenoid for a longer or indefinite period of time after take off, one will get pretty much exactly the erratic shifting described above. So yes one should indeed disable these devices for initial diagnosis.

But if that's difficult to do, consider the following first:

If it is difficult to move the shifter into the last detent and / or push it into the "B" position, this indicates the possibility that the fork shaped lever that actuates the "B" position switch in the shift gate has inadvertently been shifted into the "B" position independent of the shift lever. Look into the rearmost part of the shift gate carefully. If you find this is the case, simply use an appropriate tool to shift the fork back into the center of the gate. It should be waiting there to "receive" the shift lever as it is pulled rearwards, not already moved sideways blocking the lever. Moving this switch lever over was a common workshop prank back in the day, and somehow customers occasionally manage to displace it as well. This is also much more common with the shape and /or diameter of some aftermarket shift levers.

Also check for a stuck or displaced kickdown switch. It is mounted in the floor under the gas pedal (E-gas pedal?). These switches often stick in the depressed condition and this also results in a condition similar to what has been described. They can also be displaced from the mounting bracket and jammed. Sometimes the carpet mat will be too tight on them and not allow them to fully release.

Check for these conditions first, because it only takes minutes. These conditions are easier to check and rule out then either disabling your FGS or getting underneath things to do a proper test for inappropriate powering on of your kickdown solenoid. Every other suggestion up there is a good one and may prove necessary. After all, test is not a four letter word. But almost every car with this type of transmission control system exhibiting these symptoms, sometimes even including a dramatic 2-3 flare, has a stuck kickdown switch, and / or a stuck "B" position switch.

Good Luck!
Klink

Hi Klink,

My apologies for not responding to your suggestions. Here are the answers.

The gear shift lever goes into the "B" position just fine, so no problem there. As for the kick down switch, we might have something here. When I try to press on it, it does not go press in or out when I release the button. also, I can press on the right side of the switch and that half goes down a little bit, but does not release when I let go...I have to press on the left side of the switch to bring the right side back up. Are these hard to replace? When I get home tonight I will see if I can disable the switch as the transmission and test drive.

 

[DerFuror]

Mystery history

 

[Klink]

Hi Klink,

My apologies for not responding to your suggestions. Here are the answers.

The gear shift lever goes into the "B" position just fine, so no problem there. As for the kick down switch, we might have something here. When I try to press on it, it does not go press in or out when I release the button. also, I can press on the right side of the switch and that half goes down a little bit, but does not release when I let go...I have to press on the left side of the switch to bring the right side back up. Are these hard to replace? When I get home tonight I will see if I can disable the switch as the transmission and test drive.

You have a stuck kickdown switch. Just for clarification, that's the pushbutton switch that you see protruding from the hole in the carpet just under the gas pedal. It's a problem as common as the day is long. Access the electrical plug on the switch by carefully pulling the carpet mat in the area of the switch down and towards you in a somewhat simultaneous motion. You will see the electrical plug on the side of the switch. Unplug it. If your problem is solved, you need a new kickdown switch. You may need one even that doesn't solve your problem. It certainly sounds stuck from what you're describing. There are a couple of plastic tabs that lock it into place. you can squeeze them inwards and gently pull the switch out from its bracket in the floor. You may find that it's easier to release the switch from the bracket first, and then unplug it. That electrical plug can be tight. If you drive the car without the switch installed, don't attempt to press the pedal to the floor! That switch also serves as the pedal travel limit stop, so if you "floor it" and you will overstress your throttle cable and linkages.

You've probably just seen your proof of how gently Maui actually drives, or this "switch sticking in" would have happened to him already...

Best,
Klink

 

[gsxr]

Just FYI. The kickdown switch takes a LOT of pressure to click in & out with your fingers. Press the pedal with your foot (with engine off) and you should very clearly feel it click on & off at WOT. If it was stuck on, the trans would probably not upshift out of first gear; it would be liking having the shifter in "B" position all the time.

 

[Klink]

Just FYI. The kickdown switch takes a LOT of pressure to click in & out with your fingers. Press the pedal with your foot (with engine off) and you should very clearly feel it click on & off at WOT. If it was stuck on, the trans would probably not upshift out of first gear; it would be liking having the shifter in "B" position all the time.

So true about the pressure required to depress the switch, however be aware that the "B" position functionality requires the manual shift valve to be in position "2" and actuation of the kickdown solenoid simultaneously. A switch simply stuck down results in behavior similar to Eric's description, until you pull the lever into position "2", then it remains in first gear.

I still feel good about it...