Interesting 1-2 shift delay discovery

[luckymike]

Our E420 consistently delays the 1-2 shift longer than the spec'd eight seconds (warm or cold, doesn't matter), or whatever. It will rev too high then shift straight to 3.

I can overcome this by using more pedal than I like from a stop. This works pretty consistently but hurts mileage and bugs me to have to do it.

I've just discovered another way to trick the car into shifting into 2.

I drive with a very light foot. As I'm waiting for the car to do it's typical overrev, skip 2 and shift to 3, I can quickly move the shifter to neutral and back. This will force a shift to 2 every time and a normal shift to 3 follows.

What is that all about?

FYI, I've replaced all vac elbows and installed a new delay module (the one up behind the booster). Shifting has remained consistent over our ownership, in spite of new caps/rotors, rewired ETA, etc.

 

[gsxr]

What you describe (high revs in 1st gear, then "skipping" 2nd or staying in 2nd for a very short time) is exactly what happens with the ill-conceived FGS modification to SGS valve bodies, where a spring is removed from a certain piston. However, that only applies to SGS VB's, i.e. the stock VB in the E500E. Nobody should have modified a 400E420 VB like that. Unfortunately the only way to know is pull the pan and read the part number off your existing VB and see if it's original or not; and if so you'd then have to pull the VB to inspect for the missing spring (visible without disassembling the VB, but it has to come off the tranny).

I suppose another possibility is the spring in question has broken on your original VB, although I'm not certain if it would have the same behavior or not. At any rate, the fault is 99.44% likely to be related to the VB itself, and will probably have nothing to do with parts externally. [Update: That last 0.66% may have bit me, as Klink noted in post #6 below...]

 

[luckymike]

Well, failing any other ideas, I'll leave it for now. I've done three fluid/filter changes but don't want to pull the valve body for this issue.

I was anticipating someone saying I need to change the neutral safety switch. When pulling codes a while back, the NSS was one of the codes but at the time, I was focused on other things so I didn't relate it to the shifting.

Anyway thanks, GSXR, for the thoughts.

 

[gsxr]

Next fluid / filter change, snap a photo of the bottom of the VB for grins. Definitely would not be the NSS though.

If it were me, I'd swap out the entire VB with a used one from your local Pick-n-Pull, if you could find the appropriate year .034 donor.

 

[Klink]

I like everything Gixxer said up there. That said, your transmission is acting exactly the way they do when the kickdown solenoid is powered on, or the kickdown valve is stuck open. Before you do anything else, unplug the kickdown solenoid at the passenger side rear of the transmission and see how it behaves.

 

[gsxr]

I like everything Gixxer said up there. That said, your transmission is acting exactly the way they do when the kickdown solenoid is powered on, or the kickdown valve is stuck open. Before you do anything else, unplug the kickdown solenoid at the passenger side rear of the transmission and see how it behaves.

D'OH! I keep forgetting that darn kickdown! Klink is, as always, 110% correct. Try that first... the tranny does weird things with the kickdown solenoid powered at part throttle. I bet he nailed it.

 

[Klink]

D'OH! I keep forgetting that darn kickdown!

You're not alone. It is the most underdiagnosed condition that makes these trannies get all silly. Also, when dealing with a USA 124.034, remember that the 1-2 cold upshift delay is produced by way of the LH activating a relay that applies power to the kickdown solenoid until it "wants to" allow the 1-2 shift to occur. The 2-3 delay is then done in the more well known manner by way of switched vacuum acting on the pulling diaphragm in the control pressure cable lower housing. So, in the USA 124.036 there is yet one more failure path to inappropriately apply the kickdown solenoid. It is relay "G" also known as K29/1. It is always confusingly labeled in the wiring diagrams as the "First gear start relay module" when it is, in fact, the 1-2 cold upshift delay relay. The relay can stick on, and the ME can permanently switch it on, in addition to the usual stuck accelerator pedal kickdown switch and displaced shift gate "B position" switch...

 

[luckymike]

Klink, no joy with the disconnected kickdown switch. Next up I'll get under there and unplug the solenoid. Thanks for chiming in.

 

[Eno]

Do these above symptoms apply when you slam on the gas pedal and after transmission revs, it suddenly drops and gets stuck on first gear?
Is it the kick down switch or the wire on the passenger side tranny?
Does the bowden cable need to be checked on these cases?
We are talking about an original 92 500E Transmission.


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[luckymike]

Do these above symptoms apply when you slam on the gas pedal and after transmission revs, it suddenly drops and gets stuck on first gear?
Is it the kick down switch or the wire on the passenger side tranny?
Does the bowden cable need to be checked on these cases?
We are talking about an original 92 500E Transmission.


Sent from my iPhone using Tapatalk Pro

This post is about my 1995 E420.

I use very little pedal when I drive. As i calmly start out, whether the car is warm or cold, it will hold first gear way too long. Like sometimes up to 3,000rpm. Then it will finally shift directly to third. If it's spending a microsecond in second gear, I can't perceive it.

I can get the trans to shift through all gears one of two ways:

1. As I pull calmly away from a standstill and the trans is holding first, if I briefly move the shifter to neutral and back to drive, the trans will shift to second, third and fourth as one would expect.

2. Start out more aggressively from a standstill. The trans will shift from first to second and third and fourth just like it should.

To answer your first question, if I slam on the gas pedal at a low enough speed, the car will shift to first and then shifts to the other gears normally, earlier or later depending on throttle.

 

[Eno]

My bad for jumping in the E420 discussions, I thought the symptoms/issues of our trannies are the same that’s what meant.


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[gsxr]

Mike, what happens if you shift manually from a stop at light throttle? Start in "B", then move the shifter to "2"... will it upshift and stay in 2nd, until you move the lever to "3", etc?

 

[luckymike]

Mike, what happens if you shift manually from a stop at light throttle? Start in "B", then move the shifter to "2"... will it upshift and stay in 2nd, until you move the lever to "3", etc?

I'll check this and report back...

 

[Klink]

Unplug the SOLENOID at the transmission and report back on the result...

 

[luckymike]

Unplug the SOLENOID at the transmission and report back on the result...

Will report back on both this and GSXR's suggestion to try shifting manually.

 

[luckymike]

"Mike, what happens if you shift manually from a stop at light throttle? Start in "B", then move the shifter to "2"... will it upshift and stay in 2nd, until you move the lever to "3", etc?"

Update:

gsxr, I manually shifted the car and it works exactly as you stated.

I can shift up through each gear, the trans holding each gear until I shift to the next.

Additionally, if I leave the lever in B, the car won't shift out of first. If I leave it in 2, the trans will shift from first to second and hold second. If I leave the shifter in 2 and come back down to a stop, the trans will shift back into first.

I have not yet unplugged the kickdown solenoid at the trans.

 

[luckymike]

Unplug the SOLENOID at the transmission and report back on the result...

Klink, I unplugged the connector at the solenoid.

Current shifting characteristics remained unchanged except for the loss of passing gear downshift. I assume that was to be expected.

How annoying.

 

[gsxr]

Klink, I unplugged the connector at the solenoid.

Current shifting characteristics remained unchanged except for the loss of passing gear downshift. I assume that was to be expected.

Good info. Soooo... based on this... I'd say either:

1) The kickdown solenoid itself is stuck in the energized position (highly unlikely, but possible)

or

2) Something is screwy with the valvebody as I described previously.


#1 is easier to replace if you want to mess with it, could probably buy a used one cheap.

Klink? Any other ideas I missed?

 

[Ascension]

Watching this with great interest as this is exactly the issue that has plagued me from quite a while. Does yours hit the limiter before shifting on the 1/2 shift like my 95 420 does when it's acting up? Also mine will short shift 2/3 even at full throttle. Klink glad you chimed in on that relay as so many keep telling me there are no electronic connections in this tranny Know for a fact there is the one from the LH on that 1/2 hold. This issue has tormented me for over a year but NO ONE HAS AN ANSWER! Klink can you get me a part number and location for that #$##@ relay as can not find it
.

 

[gsxr]

Klink can you get me a part number and location for that #$##@ relay as can not find it.

On the 124.034 it is relay K29/1, located with the other relays in the rear half of the fuse box, position G.

Per this eBay listing, it appears K29/1 is a plain silver cube relay. Photo attached for reference.

 

[luckymike]

Watching this with great interest as this is exactly the issue that has plagued me from quite a while. Does yours hit the limiter before shifting on the 1/2 shift like my 95 420 does when it's acting up? Also mine will short shift 2/3 even at full throttle. Klink glad you chimed in on that relay as so many keep telling me there are no electronic connections in this tranny Know for a fact there is the one from the LH on that 1/2 hold. This issue has tormented me for over a year but NO ONE HAS AN ANSWER! Klink can you get me a part number and location for that #$##@ relay as can not find it
.

Mine won't hit the rev limiter unless I'm doing a full tilt blast from a stop. During normal acceleration, it will hold until about 3,000rpm, then skip straight to 3rd. It does not spend any time in second that I can perceive.

After experimenting with manual shifting for a few days, the car actually shifted normally for a day or so in drive. That was weird. It's back to it's old tricks, though.

And, plugging the kickdown solenoid back in didn't make a difference to anything.

 

[gsxr]

Mine won't hit the rev limiter unless I'm doing a full tilt blast from a stop. During normal acceleration, it will hold until about 3,000rpm, then skip straight to 3rd. It does not spend any time in second that I can perceive.

After experimenting with manual shifting for a few days, the car actually shifted normally for a day or so in drive. That was weird. It's back to it's old tricks, though.

And, plugging the kickdown solenoid back in didn't make a difference to anything.

What you describe above sounds a lot like something wonky inside the valvebody... my guess is either a broken spring, or sticky piston. The easiest fix / experiment would be to swap in a known-good valvebody, although this is not fun... about 2 hours of messy work and an almost-guaranteed ATF bath along the way.

 

[luckymike]

What you describe above sounds a lot like something wonky inside the valvebody... my guess is either a broken spring, or sticky piston. The easiest fix / experiment would be to swap in a known-good valvebody, although this is not fun... about 2 hours of messy work and an almost-guaranteed ATF bath along the way.

Yeah, I don't mind the work so much, having periodic access to a lift. If one comes my way eventually, I'll put it in.

Reminder that when gently accelerating and waiting for the usual shift from 1st to 3rd, I can consistently prompt a shift to 2nd by quickly moving the shifter from D to N and back to D. Car shifts to 2nd every time. I wonder if Ascension's car would do this?

I also wonder if I should change that secondary fuse box relay just for fun...

 

[Ascension]

On the 124.034 it is relay K29/1, located with the other relays in the rear half of the fuse box, position G.

Per this eBay listing, it appears K29/1 is a plain silver cube relay. Photo attached for reference.

Thanks buddy you seem to always come through for me! Do have one question do you know if can just pull that relay defeat that circuit and have it shift normally + have kickdown function or does that relay have to be there for the kickdown to work? Know it would likely lite the CEL but will it work normally otherwise??

 

[Ascension]

Reminder that when gently accelerating and waiting for the usual shift from 1st to 3rd, I can consistently prompt a shift to 2nd by quickly moving the shifter from D to N and back to D. Car shifts to 2nd every time. I wonder if Ascension's car would do this?

I also wonder if I should change that secondary fuse box relay just for fun...

I also wonder this? So to clarify your car is also hitting the limiter at WOT before it shifts to 2nd like mine does when this is acting up?? Does yours short shift from 2 to 3 at around 4K at WOT like mine does also in D? Whole scenario really screws up the drivabilty on my car badly and so far has been unfixable.

 

[gsxr]

Thanks buddy you seem to always come through for me! Do have one question do you know if can just pull that relay defeat that circuit and have it shift normally + have kickdown function or does that relay have to be there for the kickdown to work? Know it would likely lite the CEL but will it work normally otherwise??

I think it will shift normally if you pull relay K29/1, assuming the car was already shifting correctly in the first place, or if there is some problem with the K29/1 function causing it to be engaged at the wrong time. It will take you all of 5 minutes to test it out on your own car. Per the schematic I posted above, the kickdown and B-switch functions should still work normally with K29/1 removed.

However: All three items (K29/1, kickdown, and B-switch) simply energize the kickdown solenoid. If you have already disconnected this wire at the transmission for testing (as luckymike did in post #17), and the problem remains, the problem is not electrical and K29/1 isn't the culprit. If you haven't yet done this test, you need to.

 

[luckymike]

I also wonder this? So to clarify your car is also hitting the limiter at WOT before it shifts to 2nd like mine does when this is acting up?? Does yours short shift from 2 to 3 at around 4K at WOT like mine does also in D? Whole scenario really screws up the drivabilty on my car badly and so far has been unfixable.

I can't say with certainty but will test and report. As I recall, the car shifts at or near redline in each gear just as it should.