Code 41 = new ECM?

[Weeberone]

Ok. Washed the car the other day and when I started it after it was idling really high about 2000 rpm and didn't have any power. The fan comes on right when I turn the key even before the engine is started. The ccm code on the Speedo says 41 both current and stored, even after clearing. I can got no ECM codes (by grounding A and B) the light in the DIC doesn't even light up. Code 41 means a loss of communication between the ECM and the CCM

My question is will the car still run fine with a good ECM and a bad link between the CCM or is my ECM fubar?

[XfireZ51]

Ok. Washed the car the other day and when I started it after it was idling really high about 2000 rpm and didn't have any power. The fan comes on right when I turn the key even before the engine is started. The ccm code on the Speedo says 41 both current and stored, even after clearing. I can got no ECM codes (by grounding A and B) the light in the DIC doesn't even light up. Code 41 means a loss of communication between the ECM and the CCM

My question is will the car still run fine with a good ECM and a bad link between the CCM or is my ECM fubar?

Fans coming on and crap running suggest ur in default or limp home mode.
I would pull BATT neg. then see about re-seating the prom in the ECM.

[Weeberone]

Battery reconnect did nothing. I'll try the prom next

[G8nightman]

Sounds like you wet something.

[Weeberone]

Yeah, my pants when I thought of what it'll cost to replace, let alone even finding one!

[G8nightman]

Ecm are not cheap that is if you can even find one.


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[Ccmano]

Worst case Haibeck can have it rebuilt. I seriously doubt that’s the issue though. Did you wash the engine? In this case its more likely a connector somewhere.
H
:cheers:

[-=Jeff=-]

reseat the connectors on the ECM, there was someone here who had that issue with bad pin connection to the ECM..

[XfireZ51]

reseat the connectors on the ECM, there was someone here who had that issue with bad pin connection to the ECM..

Sometimes its just a matter of a bit of corrosion that needs some removal.

[Weeberone]

Ok. So after sitting over night and reseating the PROM and 4 connectors to the ECM, it seems to be talking with the CCM again. No more CCM code 41 and "Err" at number 4.

The fan stays off with the engine off now, but when starting there is still a high idle and now the check engine light comes on, which it wasn't doing before. The CCM gives a c12 code, but the ECM gives a code 14 "coolant sensor high temp" and a 41 "cylinder select error"

When I erase these codes and start the car it sounds fine for about a couple seconds the the check engine light comes on and the idle increases and it shows the same 2 codes.

Any suggestions?

[Ccmano]

You may still be experiencing the same basic problem, water in the ECM connectors. I would carefully remove each connector and blow them out with compressed air. Is the connector cover still in place?
H
:cheers:

[Weeberone]

Is the cover the thing velcroed to the top ? Then yes. I removed the connectors once. I didn't blow air on them as I didn't seem to see any moisture. They were smeared with dielectric grease from some previous owner. I just left that on, maybe I should try cleaning that?

[Ccmano]

That new ECM 41 code also indicates the memcal prom may not be seated properly. Double check that. Almost seams like water may have gotten into the ECM. You didn’t pressure wash or something like that? Leave the dielectric grease, if anything add more. This is a strange one.
H
:cheers:

[Weeberone]

No pressure wash, but I was spraying parts of the engine, perposely avoiding the ECM. I guess not careful enough. Cleaned again and now just have the one ECM code 41.

[G8nightman]

Hopefully what ever is wet dries out.


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[Ccmano]

No pressure wash, but I was spraying parts of the engine, perposely avoiding the ECM. I guess not careful enough. Cleaned again and now just have the one ECM code 41.

That’s the memcal. Check the pins and make sure none are bent. Also make sure the sure the side clips fully click in place.
H
:cheers:

[Weeberone]

I’ll have to try again tomorrow.

Ever hear of these guys?
https://uploads.tapatalk-cdn.com/20190501/eed900f8a0be32e88434ac277c396a73.jpg


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[Ccmano]

Nope, but back in the day there were dozens of tuners. If you have the original, try putting that in temporarily and see if that changes anything.
H
:cheers:

[G8nightman]

Old corvette tuner most likely outdated tune


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[Weeberone]

Nope, but back in the day there were dozens of tuners. If you have the original, try putting that in temporarily and see if that changes anything.

H

:cheers:



That’s rich. I wish I had the original. There’s a sticker on the other side which might be a date. 1995
https://uploads.tapatalk-cdn.com/20190501/18b1aa0ed13f4b3a930cc3306e6a2f98.jpg


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[XfireZ51]

I’m assuming u cleared the ECM pulling neg BATT cable right? Otherwise the 41 would still be in History.

[XfireZ51]

Ok. So after sitting over night and reseating the PROM and 4 connectors to the ECM, it seems to be talking with the CCM again. No more CCM code 41 and "Err" at number 4.

The fan stays off with the engine off now, but when starting there is still a high idle and now the check engine light comes on, which it wasn't doing before. The CCM gives a c12 code, but the ECM gives a code 14 "coolant sensor high temp" and a 41 "cylinder select error"

When I erase these codes and start the car it sounds fine for about a couple seconds the the check engine light comes on and the idle increases and it shows the same 2 codes.

Any suggestions?

Just read this part. The prom may be corrupted. If u have another one, try putting it in and see what happens. Hans had a cylinder select error come up when we were tuning his 90.

[Weeberone]

I don't have another chip to try, unfortunately. I'm not against buying one, I was going to get a Mark Haibeck one eventually anyway.

I disconnect the battery with each thing I try.

Is there anything else I could try that would make the corrupted chip theory more definitive?

I have a track day in 4 weeks and I need this bad boy running by then.

[XfireZ51]

I don't have another chip to try, unfortunately. I'm not against buying one, I was going to get a Mark Haibeck one eventually anyway.

I disconnect the battery with each thing I try.

Is there anything else I could try that would make the corrupted chip theory more definitive?

I have a track day in 4 weeks and I need this bad boy running by then.

If u have a cylinder select issue, you’ll need a chip burned to remove that flag.
Send me a PM.

[G8nightman]

Why would you think it’s the chip OP said he washed his car then everything went wrong. You said you didn’t spray water at the ecm did you spray at the motor there’s a bunch of stuff under plenum that shouldn’t get wet.


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[Weeberone]

Why would you think it’s the chip OP said he washed his car then everything went wrong. You said you didn’t spray water at the ecm did you spray at the motor there’s a bunch of stuff under plenum that shouldn’t get wet.


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The spray was mostly on the heads and frame rails, but some water could have got under plenum.

After I washed it I would normally run the engine to dry everything, but I got called away and the car sat in the sun with the hood closed. I'm thinking would have got very humid under there.

[XfireZ51]

The spray was mostly on the heads and frame rails, but some water could have got under plenum.

After I washed it I would normally run the engine to dry everything, but I got called away and the car sat in the sun with the hood closed. I'm thinking would have got very humid under there.

Its possible the coolant sensor got fried which would cause the motor to act like it does. The cylinder select could be a function of that or not. I have run into the cylinder select issue for some reason on several ZRs including mine.

[Ccmano]

Why would you think it’s the chip OP said he washed his car then everything went wrong. You said you didn’t spray water at the ecm did you spray at the motor there’s a bunch of stuff under plenum that shouldn’t get wet.


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That’s where the codes are pointing us too. It’s possible a short elsewhere caused an issue with the chip. You have to follow the trail of the codes. Codes only point you to possible problem area. They do not tell you precisely what’s wrong.
H
:cheers:

[G8nightman]

That’s where the codes are pointing us too. It’s possible a short elsewhere caused an issue with the chip. You have to follow the trail of the codes. Codes only point you to possible problem area. They do not tell you precisely what’s wrong.
H
:cheers:

:-D:-D:salute:

[Weeberone]

I took out the chip one more time. Made sure it was seated properly (with the battery disconnected). Put it back together, hooked up the battery, made sure there were no stored codes and started her up. Idled around 2000 still and after about 10 seconds the check engine light came on. Checked the code, still code 41. I guess I’ll get a new chip see how that goes.


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[XfireZ51]

I took out the chip one more time. Made sure it was seated properly (with the battery disconnected). Put it back together, hooked up the battery, made sure there were no stored codes and started her up. Idled around 2000 still and after about 10 seconds the check engine light came on. Checked the code, still code 41. I guess I’ll get a new chip see how that goes.


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So no more coolant temp code?

[Weeberone]

So no more coolant temp code?

No coolant code. That one went away after the first time I completely disconnected the ECM and blew out the terminals. Just the 41 on the ECM codes now. The CCM codes give a C12 which I believe means all good.

I sent you a PM.

[Hib Halverson]

What model year is this car?

[Weeberone]

What model year is this car?

1990

[Hib Halverson]

That’s rich. I wish I had the original. There’s a sticker on the other side which might be a date. 1995
https://uploads.tapatalk-cdn.com/20190501/18b1aa0ed13f4b3a930cc3306e6a2f98.jpg


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That's probably the date that the "tuner" burned the chip.

I'm thinking there still is a problem with a bad connection at the memcal connector in the ECM. I base that on the fact that the code 14 went away after cleaning the ECM connections which tends to reinforce the idea that the problem is a bad connection that became bad during the washing process.

Before I'd spend the money on a new cal chip, I'd go buy yourself a spray can of electrical contact cleaner. Usually you can find that at an electronics supply store or an industrial hardware store but maybe even Lowes or HomeDepot.

Unplug the four ECM connectors and spray contact cleaner into both the connectors and the ECM sockets. Then carefully plug and unplug each connection a couple of times. Finally, spray contact cleaner on the connectors and sockets, again, and let the cleaner air dry away for several seconds, then reconnect all four connectors.

Then, remove the cal chip, spray contact cleaner onto the socket in the ECM and on the bottom of the chip. Then carefully install and remove the chip a couple of times. Finally spray contact cleaner on the socket and the chip again, let them dry then reinstall the chip.

Clear codes and road test.

If code 41 resets, replace the cal chip. If the code still persists, replace the ECM.

[XfireZ51]

Hib,

I think he was going to get a performance upgrade cal from Marc Haibeck anyway. This way he’ll kill 2 birds ...

[Weeberone]

New MH chip on the way.

I cleaned the contacts once already with some 99% isopropyl. I do have some DeOxit for my audio equipment, I’ll give that a try just like you describe. There’s a lot dielectric grease on everything, makes it hard to clean.

If this new chip fails to get rid of this code, anyone out there have a working ECM for sale, just in case I need it?

[XfireZ51]

If u r checking codes, the first one u should get is a
Code 12 which is an ECM self test. If u get that, the ECM is ok.

[Weeberone]

If u r checking codes, the first one u should get is a
Code 12 which is an ECM self test. If u get that, the ECM is ok.

Yes, under category 1 I get a C12 then the 3 dashes - - - then under category 4 I get H41 then the 3 dashes - - -.

To you, that indicates a healthy ECM?

[XfireZ51]

From what u are describing, the codes u r getting are on the cluster and from the CCM, nit the ECM. ECM CODES will flash on the DIC.

[-=Jeff=-]

Yes, under category 1 I get a C12 then the 3 dashes - - - then under category 4 I get H41 then the 3 dashes - - -.

To you, that indicates a healthy ECM?

C refers to CURRENT Codes

H refers to HISTORY Codes

I think you have no active codes.. if it was a C41, then I would be a bit more concerned..

What are the symptoms you are seeing?

[XfireZ51]

So the 90’s show ECM malf codes on the cluster not the DIC?

[-=Jeff=-]

Both, depends how you are checking it..

[Weeberone]

C refers to CURRENT Codes

H refers to HISTORY Codes

I think you have no active codes.. if it was a C41, then I would be a bit more concerned..

What are the symptoms you are seeing?

Does it matter if it’s running or not? I check with it not running.

When it is running it idles at about 2000 rpm and stumbles and dies if you try to drive.

[-=Jeff=-]

C41 will not cause a stumble and die.. I did a 1991 dash in a 1989 and tried to use a 1992 CCM, it would not work and I had a Code 41 (Active) but yet i could drive the car.. no issues

I ended up with a 1991 CCM to fix the issue, however.. I think you are looking in the wrong spot for the issue you are having

[Ccmano]

We are focused on the ECM and Memcal here, but these symptoms sound an awful lot like a vacuum line off on the MAP sensor or even a bad MAP sensor. Have you checked the MAP sensors?
H
:cheers:

[XfireZ51]

Well if its an ECM MALF then it would cause the issue he is experiencing.
Basically its defaulting to limp home mode.

[-=Jeff=-]

Well if its an ECM MALF then it would cause the issue he is experiencing.
Basically its defaulting to limp home mode.

It's not.. he sadi Module 1 is C12 ( that is ECM

Module 4 is H41, that is CCM

HE has another issue, not ECM related in my opinion..

[Weeberone]

It's not.. he sadi Module 1 is C12 ( that is ECM

Module 4 is H41, that is CCM

HE has another issue, not ECM related in my opinion..

I thought module 4 was ECM as it reads “Err” when not communicating with the CCM, which it was doing when this started. That went away after cleaning contacts.

The vacuum hose is still attached to the MAP sensor.

[-=Jeff=-]

just checked the FSM.. yes.. 1 is CCm 4 is ECM

Error is 41 Cylinder Select

see diagnostic pages attached

[Ccmano]

The vacuum hose is still attached to the MAP sensor.

Both ends? An easy check of the MAP sensors is to swap the two MAP sensors in their respective locations and see if you get a change. The other one is under the ECM on a 90’. No change means that’s not the problem.
H
:cheers:

[Weeberone]

Well my Haibeck chip showed up about a week ago. The car had been sitting for about 2 weeks, so before I put in the new chip I thought I’d see if it was still throwing codes. Well, of course it starts and runs perfectly. I guess it just needed a really good dry out? I don’t know.
Anyway, with a perfectly good Haibeck chip sitting on the bench 3 feet away what would you do? Of course, put that bad boy in.
So I put in the new chip and start it up. Instantly the CEL comes on. It seems to be running fine though so I take it for a drive.
Obviously there’s an issue as it won’t rev with any power above 5K rpm.
Turns out, in my haste and excitement I didn’t have the new chip seated properly.
Once that was fixed the car ran great!
The best part is the high idle that used to hang about 1200rpm for a few seconds while coasting to a stop drops much faster now and sounds like a normal car.
I’m still having an issue of what I perceive as slightly rough running while accelerating, but I’ll start another thread to ask advice about that.
Thanks for all the help on this problem!


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[Ccmano]

That’s good news.... are the injectors original? Plan on changing them if they are, a good chance that’s your roughness.
H
:cheers: