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SF Bay Area Diagnostic Code Experts?

luckymike

Member
Okay, I need help and can't do this on my own. I'm looking for someone near San Carlos in the San Francisco Bay Area who has the equipment for reading and clearing codes and is confident using it.

1995 E420. The check engine light comes on occasionally. When this happens, I use the pushbutton under the hood to read and clear the codes (usually 4 and 26, I think) and the light goes out.

Recently I came across instructions to 'reset adaptation'. While trying to do that, I discovered that I still have code 26. It hadn't cleared, even though I did the 6-8 second button push. So even though my CEL is out, I still have the code.

The car runs fine, other than it skips second gear every time. I just need someone to help me get an understanding of the true state of the current codes.

Anyone near me willing/available to help out?
 

gerryvz

Site Honcho
Staff member
Wish I would have known, I'm in Redwood Shores today through Thursday AM. I would have brought my Trisco with me on the plane to do some scanning and resetting for you.

Resetting adaptation isn't going to have any effect on codes.

Have you checked GSXR's code sheet for the M119? http://www.w124performance.com/docs/mb/diagnostics/DTC_List_W124_M119.pdf

You'll want to look at pages 24-25 of the PDF, for pin #19 (which is the Diagnostic Module -- DM) that controls the check engine light.

:cel:
 

gsxr

.036 Hoonigan™, E500E Boffin
Staff member
Code 4 is related to the air pump... could be the pump itself, valves in the pipes, vacuum signals to the valves, or an O2 sensor. Difficult to troubleshoot.

Code 26 is related to the cold upshift delay circuit, you'll need to check the vacuum lines on that one.

Skipping second gear is odd; that may be a valvebody issue (also not fun to troubleshoot). I'm assuming it holds 1st gear normally based on throttle position, shifts to 2nd, then immediate shifts to 3rd even if you had your foot in the pedal a fair amount.

Gerry is correct - resetting adaptation is only for the fuel mixture. It would have no effect on any of the issues described above.

:cel:
 

luckymike

Member
Okay, let's see. I wasn't trying the adaptation reset in order to fix any problems, I just thought it would be nice to reset to a baseline. The thing is, in trying it I discovered I still had an uncleared 26. And this code won't respond to the 6-8 second clear so that I can move onto any other steps. I never get the single (or is it double?) blink confirming codes are clear, even though the CEL is out.

So I'm hoping to find someone (Gerry on a future trip?) who could do a general scan and then reset stuff. After that I can check DCs going forward. I know how to read them off the 16 and 38-pin connectors.

Not the purpose of my request post but for info: The second gear skip is interesting. If I put my foot firmly into it (I usually start off very gently), I will get normal shifting every time. But doing a typical gentle start from a standstill, the car skips second every time. It isn't hitting second for a split second then going to third, it just goes straight to third. And at about 23mph every time, consistently.

I can force a shift to second gear by gently accelerating from a stop and quickly moving the shift lever from D to N and back again. I get second every time which then shifts to third as one would expect.

gsxr, I have read many posts from this board pertaining to this issue and have done the vac tests, the bb test, etc. I've tried a spare relay up at the firewall, changed all the rubber elbows, replaced vac lines. I can't hold vac on the line going down to that unit on the right side of the trans so I guess I might need to change that. But if so, why does the car shift to second when under low speed load?

But that's not why I'm writing. I just want to get the codes read and cleared on this thing so I can move forward.
 

gsxr

.036 Hoonigan™, E500E Boffin
Staff member
If the CEL is off, the DM codes have cleared. The DM generally requires an engine start after clearing, and does not always show 1 blink when no codes are present, which is different from all other modules. Are there codes on any other modules? If the vac tube to the passenger side of the transmission won't hold vacuum, that is likely the root cause of your DM code 26.

The transmission shifting discussion would be best moved to a separate thread, to get comments from other people who know more about this stuff. Note that if you want 2nd gear, move the shift lever to position "2". The trans will start in first, shift to second, and stay in second until you move the lever out of position 2. In general I'd avoid selecting neutral while accelerating.
 

luckymike

Member
My CEL is off. When I press the button on the 16-pin for 6-8 seconds, my understanding is I should get either nothing, or a single blink if no codes. But I get a repeat of the 26 blinks, even though the CEL is off. What should I do next?
 

gsxr

.036 Hoonigan™, E500E Boffin
Staff member
Ah, now I see what you mean. I believe the DM can have stored codes without the CEL on. It wants to see the same error more than once before triggering the CEL. The CEL may come on eventually if you keep driving it without clearing anything. Code 26 is mostly a nuisance, I'd ignore it unless you get tired of seeing the CEL and want it to stay off.

:scratchchin:
 

luckymike

Member
Okay! That's what I'll do.

Still looking for someone somewhat near me to scan this car so I can know where it stands. Anyone near San Carlos?

Or can we get together on one of your trips, Gerry?
 

gerryvz

Site Honcho
Staff member
I won't be back here until probably end of April, but if you want to set something up I'm happy to. Usually here for 2-3 nights at a time. Be happy to treat you to dinner, courtesy of my Uncle Larry.
 

Jlaa

Active member
Mike,

I don’t have any more diagnostic equipment than what you have. Happy to be a part of the end of April diagnosis party. Let me know.
I'm 30 min from San Carlos and like RicardoD I don't have any additional equipment other than these simple tools --- I'm assuming you don't want to take your car in to local shop for 1 hr of code reading time?

8162981630
 
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