Tricking Electronics for Manual Swap

[anderzen]

Hello All,

I am in the middle of my manual swap on my 94' E420... Wanted to start a thread to collect answers and share information I discover on how to most conveniently and efficiently trick the ECU and electronics to keep things happy and most importantly running right with full powaaaa

.... So far from speaking with a few who have done this in other similar platforms and speaking with @gsxr it sounds like one of my main hurdles potentially will be tricking the ECU in regards to the overload switch from the auto trans and figuring out what to do with the NSS (N/P lockout was bypassed already)...
I have a handle on the hardware in regards to components for the swap, but am completely out of my element as far as knowledge of this ECU and it's quirks. My hope is that this thread will help by the power of committee to find a viable solution and will in turn take out the stress from this part of the equation later on for any others who will go down this gear rowing river after me...
Here are some behind the scenes pics for fun to get things started








BIG Thx in advance for any willing to share any ideas or things to try or look out for... No idea as of right now what will happen when it starts back up lol!

ANDERZÉN

 

[gsxr]

FYI... there is normally a threaded stud at the passenger side top, above the starter. It has been removed as seen in your photo below.

I assume you cannot use the original stud with the adapter plate, it may be too short? If so, you MUST use sealant on the threads of whatever bolt/stud replaces it. This hole goes into an oil galley and you WILL have an oil leak if sealant isn't used...

 

[anderzen]

Yes, stud had to be removed for the adapter flange, a bolt takes it's place. I did NOT know it require sealant, THANK YOU Dave!!!!!

 

[gsxr]

I learned this the hard way... pulled a transmission three times to replace what I thought was a leaking rear main seal (three times!) before I figured it out.

 

[anderzen]

Ouch that is rough.... I can't thank you enough! glad I posted this thread for this answer alone... I would have never thought to check that with all of the other little details swirling through my head on what to tackle. Added to the LIST!

 

[anderzen]

Any recommendation on sealant btw @gsxr ? I do have a fresh tube of black MB sealant I haven't used....

 

[gsxr]

Any recommendation on sealant btw @gsxr ? I do have a fresh tube of black MB sealant I haven't used....

I was replacing the stock threaded stud with a new OE part that had pre-applied, micro-encapsulated sealant - same stuff as on the 8 bolts which hold the flywheel/flexplate to the crankshaft.

I'm not sure what to recommend otherwise. The black sealant (Loctite 5900) may be fine, but remember this is going into an oil passage so you do NOT want any excess sealant getting in there. I'm wondering if an anerobic might be better, if there is one designed for threads? Oil-resistant threadlock compound might also work. Wish I knew what the yellow stuff is on the OE bolts/studs.

 

[anderzen]

ended up using Permatex thread sealant

 

[anderzen]

Revamping this thread as I sort through this, I will be the guinea pig... lol. I tracked down the transmission harness plug. The speed sensor, b position, kickdown switch and solenoid, OL switch and NSS all plug into one plug behind the radio. I have sorted through the 12 pin bushings and wire colors to know what does what for the most part but maybe someone familiar with the NSS can help me determine the ones I don't know...

there are three wires on the NSS which I don't know, green, pink, grey/yellow. I believe there were six pins total on the NSS, I'll have to look back at a diagram I know I have seen around here on the NSS and what each part does...

Other question: Does anyone know what pulse per minute the E420's cluster operates at? I am going to use GPS speed sender but need to know if will be able to calibrate. Typically they are 4k, 6k or 8k+

 

[anderzen]

Rough diagram, I’ll translate this to digital in illustrator for futures goers…

My plan currently is the keep neutral lockout jumped. And plug in gps to speed sensor inputs… time will tell if I will need to trick the OL switch also…

 

[anderzen]

Looking for some help with GPS speed signal sender... does anyone know the pulses per minute for the W124 clusters?

 

[a777fan]

Having never looked into this, I’m not surprised I have a stupid question, so here it goes…

I’m confused by the question. What is ‘pulses per minute’? For the speedo, wont the number of ‘pulses’ be proportional to whatever speed the vehicle is traveling? Or… is this ‘pulses per minute’ speedo tech language regarding some sort of industry standard?

 

[anderzen]

No not a stupid question and in all honesty I’m just learning about this myself, from what I understand different makes and models use different ppm to calibrate the speed signal received. I believe these operate at 4k ppm but other common standards are 8k, 16k etc… my gps sender only has 4k, 8k and 16k options so I’m hoping one of these works.

 

[a777fan]

No not a stupid question and in all honesty I’m just learning about this myself, from what I understand different makes and models use different ppm to calibrate the speed signal received. I believe these operate at 4k ppm but other common standards are 8k, 16k etc… my gps sender only has 4k, 8k and 16k options so I’m hoping one of these works.

Got it! So yeah.. its like some sort of industry calibration standard. Thx.

 

[a777fan]

If the settings on the sender are easy to change, perhaps you just send it and use trial and error?

 

[anderzen]

Yea, that’s the plan! process of elimination. 1/3 chance to get lucky

 

[anderzen]

I also just found this article which is helpful and shows some ingenuity with using the existing speed sensor…. Hmmm

W124 Mechanical to Electronic Spedometer - PeachParts Mercedes-Benz Forum

Referencing this thread: http://www.peachparts.com/shopforum/diesel-discussion/312801-mechanical-electronic-speedometer-conversion-3.html I am in the

www.peachparts.com

 

[anderzen]

Just to update, still working on this, we are getting closer! Will post everything once complete and won't leave this thread hanging like I disappointingly find too often on the interwebs ha!

 

[Jlaa]

Revamping this thread as I sort through this, I will be the guinea pig... lol. I tracked down the transmission harness plug. The speed sensor, b position, kickdown switch and solenoid, OL switch and NSS all plug into one plug behind the radio. I have sorted through the 12 pin bushings and wire colors to know what does what for the most part but maybe someone familiar with the NSS can help me determine the ones I don't know...

there are three wires on the NSS which I don't know, green, pink, grey/yellow. I believe there were six pins total on the NSS, I'll have to look back at a diagram I know I have seen around here on the NSS and what each part does...

Other question: Does anyone know what pulse per minute the E420's cluster operates at? I am going to use GPS speed sender but need to know if will be able to calibrate. Typically they are 4k, 6k or 8k+

I believe @kegmankipp recent did some kind of E420 speedometer signal conversion with some yellow box doohickey along with hard lessons learned about some unclear wiring or something like that?

 

[anderzen]

I have a GPS Speed sensor that I am pretty sure will work but have been smoothing out other parts of the project. Hopefully this week/weekend I'll get time to throw it in.

 

[Rouven036]

I was also long time fantasising about a manual conversion however for me it is important to have a proper oe fit and finish plus full functionality on original electronics.
The speed signal you could adequately get without any additional GPS Modul etc while getting 4 signals per output shaft revolution to the speedo. This could be done by a special machined signal ring fitted to the output shaft flange, by modification of the output shaft flange etc. A bracket must be fitted onto the transmission to hold the original or aftermarket inductive sender.

For the overload protection switch, iirc is the signal only issued in certain shifting conditions - so I thought that it could possibly work while installing the overload protection switch in the clutch hard line (Master to slave) with an appropriate fabricated bung/hard line.
However I couldn't figure what are the operating pressures to actuate the switch and if this pressure would match the one when actuating the clutch.

Starter lockout is to be bridged at the fues box as it is anyhow on manual cars.

Another topic was prnd recognition which would needs a resolution. R is the simplest via the reverse light signal switch at the shifter or transmission.

 

[anderzen]

Thank you for chiming in @Rouven036 I very much appreciate it!
Yes I saw in the thread on peachparts I posted above how I could make what you describe for the speed signal. Interesting option but I'll see if I can get the GPS to work first than divert back if not.
I've heard that possibility of hooking the OL switch to the clutch pedal or to the line but still don't know if it is something I will even need to operative. The other day I hooked the NSS back up and set it to drive, the car seemed much happier and was idling just fine so that is promising. I need to lockdown my shift rod because one of the locknuts came loose, once that is corrected it will go out for test drive number 3 and I'll update from there.
Is the a picture of the starter lockout bridge you mention? I'll search around for that in the meantime...

 

[Markus-MD]

in my mind the overload switchis only for reduce the ingnitionangel during too shift under flatout or near from this(Highload shifting).you can take an switch on the clutchpedal from normal handshift gearbox .and push the clutch the switch reduce the ingnition and maybe al is fine.The switch was only for (Overlive the gearbox ) But i mean i remeber the Overloadswitch has an built in Resistor not sure 80 OHM .you must measure this.

 

[gsxr]

I've heard that possibility of hooking the OL switch to the clutch pedal or to the line but still don't know if it is something I will even need to operative.

Read the FSM for more info on the OL switch function. Job 15-0020, section J.

Sorry, I don't know how this applies to a manual conversion:

 

[TerryA]

@anderzen, @gsxr, Mercedes had to address this issue on their manual shift transmissions.
I know MB sold 90s models 300 SLs with manual transmissions albeit I’m not sure which years that MB offered that option.

Would there be a proper answer for the Overload Switch in the Field Service Manual for say a 1993 to 1995 129-300SL model with a 5 speed manual?

I would think that they would have similar electronics to the E420 or an E500E. Maybe you should check out the 300SL schematics for an answer?

Just a thought

 

[gsxr]

@TerryA , I was wondering the same thing. The 722.3 transmissions used with V8 and V12 all have the OL switch. But I don't know if any 6-cyl versions had the same switch... never investigated this. The R129+M104 with stick shift would be a good starting point for research.

 

[Glen]

As I recall, only CIS-E cars were available with manual transmissions so I'm not sure how helpful that will be.

 

[gsxr]

As I recall, only CIS-E cars were available with manual transmissions so I'm not sure how helpful that will be.

Glen, I think you are correct for the R129.061, which was CIS-E.

Might need to look at ROW (non-USA) models with EFI and manual trans and see what's in the EPC.

 

[Rouven036]

Thx Dave for pulling the info from the manual. Yes there is the croux - the emergency running if the ezl doesn't receive the ol switch signal.
So yes, it must be fitted somehow, alternatively a suitable pressure switch could be installed in the hard-line to the clutch with the specific resistor to meme the same type signal to the ezl....

Could be very well that there are different ezl available for manual and automatic cars. Definitely the case on the 2.5-16 and sure the 300 24v too. Other then these plebeian models where you have to mix the gears by hand, the V8's never came with that option and an ezl without this function. That's the price to pay for royalty....

 

[anderzen]

Welp... got the shifter locked down properly and took it out for the first test drive with the NSS set to D... Success! She drives normal, revs out through all gears and shifts with ease even at high rpm. At 60mph I'm right around 1500rpm in 6th, if I used the freeway much I guess that would add up to a few mpg's gained, but I mostly city drive it.

Now unrelated we have a mysterious slow dribble brake fluid leak coming from the passenger side trans tunnel, looks like it's coming out from near the lower harness cutout hole, but the brake line near there is all dry.. we are pretty stumped on this one so gonna take some searching to find out where the heck it could be coming from... all of the clutch lines are dry and the clutch reservoir was good, the brake fluid reservoir was down a bit.

Edit: Other notes..ASR is still active and working, broke traction in first gear on a turn and saw the triangle light up on the dash as it normally would before. Now, back to editing 3.5hrs of footage....

 

[anderzen]

leak seemed to have solved itself luckily, the car sat for about 7 weeks which isn't great for any old car that is weeping fluids from a few places... but the leak basically turned to what felt like greasy water after a day or so and now is totally gone. Keeping an eye on things actively though.

Other news, no go on the GPS speedo as of now.. still toying with it, but everything else on the car is working good. I basically used the signal plug that the factory speed sensor used and it's ground, GPS fired up fine but no needle movement. Might try to wire it straight the speedo, but there is still no guarantee my GPS unit is compatible PPM and wave type wise... Have another buddy working on the same thing so hopefully one of us finds the answer soon and I will share once so.
I guess this thread is for the most part a wrap, NSS set to D is the easiest option aside from going standalone or reconfiguring the ECU if possible. I may try Megasquirt down the road but for now I am happy.. AND it's been a good chunk of time and driving and still no CEL... kind of bizarre, but I'll take it even if it doesn't stay that way.
Thank you everyone for the help, I do plan on making a detailed thread on the whole swap down the road and the 8 part playlist will be on my youtube channel Friday July 1st.

Thx!
ANDERZÉN

 

[anderzen]

FEW updates... I know it has been a while but I haven't forgotten about these threads, just been very busy

1) Speedo/Odo is now working, signal required is 8K AC sine wave type, I used the generic GPS unit I had originally with no luck because I found out it was square wave type. SO, I re ordered the Dakota Digital SGI-100bt and used it to convert it back to sine wave. This will be covered in an upcoming 'Update post-manual swap' video.

2) The mysterious brake fluid leak... turned out to be the dang o-ring on the universal Wilwood clutch fluid reservoir... was crimped out of the box and slowly dribbling down the firewall to the lower wiring harness inlet above transmission, new o-ring is on and no more leaks (well my engine and power steering are but that's another job for another day haha)

3) With more and more miles being put on, I realized the OL Switch definitely causes some weird behaviors at times. In 2nd gear on hard pulls it will sometimes cutout momentarily at high rpm just as described in the doc that @gsxr posted above... I will experiment with this until I figure it out, but I am not sure where to start besides resistors or jumping the plug. I have no idea what bar of pressure the switch looks for in order to replicate a signal of any kind, kind of out of my league on that one but if anyone has ideas please share!
I guess current question I have would be.. If I jumped the plug, wouldn't that represent the switch being 'on' and therefore cut timing constantly? If so, how much does timing retard during this process?

4) I will have a write up detailing the whole swap process and any easter eggs I can share to make this easier for the next who will attempt this. Just need some down time and I'll make it happen!

Thx!
ANDERZÉN

 

[Markus-MD]

Hi Anderzen.Take a old gearbox an a measure the Resitance on the Oveloadswitch. With this value you order a Resintor an fitted on the kabel .thats the cheapest way .Better wa you take a swicht to clutch pedal in serie and wen you push the pedal the switch makes kontakt and reduce the ignitionangel on the ezl. ist OL switch open the ezl rember this. he is checking the Resitor from the switch ,hope thats help

 

[gsxr]

I believe the OL switch is either open or closed (infinite or zero resistance), not a particular resistance (X ohms). The computers expect this signal change when the shift is in progress, which would be difficult to simulate. Pressure rating is 1.8 bar, +0.2 bar (i.e., 1.8-2.0 bar).

When this switch is disconnected (i.e., broken wire, which is not uncommon) there is a slight hesitation at the WOT upshift. But the engine will pull smoothly to 6000rpm. If there's a hesitation at a lower RPM, it may be a different problem.

What changed after post #30 above from June, when it would rev through all gears and shift ok at high RPM?

 

[Markus-MD]

I have not an old swich here .Also Anderszen must measure this part .not sure with the resistor but i remember me that i read from .
but what say my portuguese Friends "Calma""

 

[anderzen]

I think hesitation is a more accurate description, it's not repeatable every time, but most often it happens at around 4-5k rpm under WOT and only in 2nd gear. It will hesitate for a millisecond and then continue through the rest of the rpm. Nothing changed since my previous posts besides more driving time and learning things about the setup.

I just went out for a test drive with the OL plug jumped DON'T DO THIS... lol car was not happy after a few miles.

One thing that has begun, is the notorious fuel pump relay click... so I am wondering if my LH module is dying and if I should swap back in my original? And if that could have anything to do with this hesitation?

I still have the whole auto trans which will be parted out here soon and the OL plug is on it, if there is something worthwhile to try with it.

 

[gsxr]

FPR click = LH module. Swap in a different one, or replace the caps. Shouldn't have anything to do with the hesitation, but you never know.

 

[anderzen]

Yea this is the old WOT one I swapped in off Ebay, so I'll throw in the stock one and try to rebuild the current one.

 

[anderzen]

Original LH module from 94' back in the car, no more clicking and the car is running nicely. Still a slight hesitation right around 4.5k but only under WOT and in 2nd gear... something to live with for the time being as the car is working well otherwise.

 

[anderzen]

Alright, we finally have the car fully happy running wise... somehow I hadn't tried setting the NSS to Park and lo and behold once I did, no more hesitation at 4.5k rpm in 2nd gear!! The car seems happier overall too, every once in a while previously it would feel stumbly in 3rd gear almost like the ecm wasn't happy, but that is also no longer.

So final setup as for now...
-Keep trans harness plugged into female connector that lives behind radio and tunnels up to cluster.
-Keep NSS hooked up and set to P
-Dakota Digital Speed signal and GPS sender of choice plugged into factory spot for speed sensor from auto trans (Pin 1, 2, (PWR, SIG)) and a chassis ground of choice.

Other notes, I do have OL switch still plugged into harness but isn't doing anything.
Now that I feel like I have the car sorted of bugs *fingers crossed* expect a 'How-to' post within a week or so with details and pictures, along with pricing and whatever else i can think of. Thanks so much to all who have chimed in. What a crazy but fun adventure this has been!

-ANDERZÉN

 

[Rouven036]

That hesitation you described could be very well caused by the missing ol signal.

Interesting is the stuff you write above, because iirc (not sure) the manuals say somewhere that the rpm in p is limited?!
So maybe same time you feed it with a speed signal that is overriding? As in stock setuo there can't be a speed signal in p as the car by default is stationary.
Also what speed signal/frequency do you feed the ecu with? Original? (mile/tire circumference * diff ratio * 4) 4 is signal count per revolution from the transmission.

 

[anderzen]

revs are not limited in P fortunately but you’re idea about the speed signal offsetting or overriding could be possible. I think that it’s no longer looking for OL signal because there was never supposed to be one sent in park. The hesitation I also agree was most definitely caused by the missing OL signal.
Mentioned in post #32 I’m using 8k AC sine wave signal for speedo which is factory. Most aftermarket gps units are squarewave so you need a signal converter.

 

[gsxr]

How are you confirming the NSS setting is "Park"? Do you have SDS + HHTWin to verify in live data?

Good to hear it's all getting sorted out!

 

[anderzen]

By setting NSS lever all the way to one side, I know it’s the correct side based on orientation when it was in the car.
Plus it’s idling at 600rpm versus 500.

 

[gsxr]

By setting NSS lever all the way to one side, I know it’s the correct side based on orientation when it was in the car.
Plus it’s idling at 600rpm versus 500.

Got it. Note that may or may not actually be indicating "Park" to the computers, the NSS is a little weird with the detents. If it's in between actual positions the computers don't recognize it as any position, which shows up as a "F" in live data (Fault or Fail, I assume). The important thing is that it's running better though!

 

[anderzen]

Yes learned how touchy it is when trying to land perfectly on R to test reverse lights. Has to be in the exact correct position. In the case of Park I think it’s pretty easy to land on fortunately