ECM, no code 12, problem?
Thread Starter
Drifting
Joined: Nov 2015
Posts: 1,695
Likes: 324
Finalist 2020 C4 of the Year - Unmodified
ECM, no code 12, problem?
Hey all, bad day. 
Started with flushing my radiator. Coolant out, water in, start time. I did disconnect the battery during this.
Battery connected, engine started, ran for about 1-2 seconds and dropped. Haven't been able to get a start since. It turns over fine, sometimes gets the occasion rumble. Other item, the radiator fan is going full boar when ignition is on (before start). Didn't before.
I decided to check for ECM codes, shorted A+B (done this before) and I'm getting zero codes. No 12, no blink at all.
Ugh.
Did I mention I have my first Corvette club meeting in 2 days? 
Before the coolant flush, Lady ran great, started quickly and no engine problems.
Any pointers?
Started with flushing my radiator. Coolant out, water in, start time. I did disconnect the battery during this.
Battery connected, engine started, ran for about 1-2 seconds and dropped. Haven't been able to get a start since. It turns over fine, sometimes gets the occasion rumble. Other item, the radiator fan is going full boar when ignition is on (before start). Didn't before.
I decided to check for ECM codes, shorted A+B (done this before) and I'm getting zero codes. No 12, no blink at all.
Ugh.
Did I mention I have my first Corvette club meeting in 2 days? Before the coolant flush, Lady ran great, started quickly and no engine problems.
Any pointers?
Instructor
Joined: Oct 2015
Posts: 134
Likes: 6
From: Osceola WI
I would make sure to check the fuse for the ECM and fusible links etc. Double check any sensors you may have disconnected. I assume you didn't disconnect anything but thought I would mention it in case you had stuff off for bleeding etc.
does the security light blink?
does the security light blink?
Thread Starter
Drifting
Joined: Nov 2015
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Finalist 2020 C4 of the Year - Unmodified
Security link does blink, starter does crank. Think I just hit bad luck and ECM happened to go.
I started going through FSM diagnosis today, "chart A-2". So far, all is pointing to ECM or MEMCAL. Just reseated, time for retry.
Team Owner
Joined: Jul 2004
Posts: 28,378
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From: Hartford WI
You might have better luck finding a solution if you would update your location. Someone might be able to temporarily lend you an ECM to test. I can't because I don't know where you are and my ECM is from a 91 and I don't think it would fit your 87 but someone in that region might.
Race Director
Joined: Oct 2011
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From: Dallas Texas
2025 C4 of the Year Finalist - Modified
Too see of your ECM is bad, put the key in on the position.
Get a multimeter
Point black probe to a good ground
Red probe to the TPS, ECT, IAT, one at time of course.
You should be getting 5 volts, battery MUST be in good shape
Too high, dirty ECM grounds
Too low, most likely bad ECM
But I agree, I'd check fuel pressure-it's easy
Get a multimeter
Point black probe to a good ground
Red probe to the TPS, ECT, IAT, one at time of course.
You should be getting 5 volts, battery MUST be in good shape
Too high, dirty ECM grounds
Too low, most likely bad ECM
But I agree, I'd check fuel pressure-it's easy
Last edited by 1993C4LT1; Jul 20, 2016 at 10:09 PM.
Thread Starter
Drifting
Joined: Nov 2015
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Finalist 2020 C4 of the Year - Unmodified
Success!! 
I stepped through Chart A-2 from the FSM, had to remove ECM and check MEMCAL. I did the old method, pop the MEMCAL and push back in about 8 times. Re-connect, ignition on....code 12! Remove paperclip and BaBaBaBaROOOOM!!
Back to running great!
Now time to finish radiator flush and DRIVE!!
I stepped through Chart A-2 from the FSM, had to remove ECM and check MEMCAL. I did the old method, pop the MEMCAL and push back in about 8 times. Re-connect, ignition on....code 12! Remove paperclip and BaBaBaBaROOOOM!!
Back to running great!Now time to finish radiator flush and DRIVE!!
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Thread Starter
Drifting
Joined: Nov 2015
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Finalist 2020 C4 of the Year - Unmodified
Update: fix didn't last long.
Little driving in the heat (94 F of course), ECM failed again. SES flicker, no code 12. Poot. Worked a little after cooling, lucky enough to make it back to garage. Time to replace. Hoping the MEMCAL is okay.
aklim: ECM is electronics, 29 year old electronics. Boards age over time, especially when created on 1980's tech level. All it takes is one component or a board trace to stop working, corrode or break. I noted board traces were popped off the board, looked like wrinkles.
Little driving in the heat (94 F of course), ECM failed again. SES flicker, no code 12. Poot. Worked a little after cooling, lucky enough to make it back to garage. Time to replace. Hoping the MEMCAL is okay.
aklim: ECM is electronics, 29 year old electronics. Boards age over time, especially when created on 1980's tech level. All it takes is one component or a board trace to stop working, corrode or break. I noted board traces were popped off the board, looked like wrinkles.
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Race Director
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From: Dallas Texas
2025 C4 of the Year Finalist - Modified
Update: fix didn't last long.
Little driving in the heat (94 F of course), ECM failed again. SES flicker, no code 12. Poot. Worked a little after cooling, lucky enough to make it back to garage. Time to replace. Hoping the MEMCAL is okay.
aklim: ECM is electronics, 29 year old electronics. Boards age over time, especially when created on 1980's tech level. All it takes is one component or a board trace to stop working, corrode or break. I noted board traces were popped off the board, looked like wrinkles.
Little driving in the heat (94 F of course), ECM failed again. SES flicker, no code 12. Poot. Worked a little after cooling, lucky enough to make it back to garage. Time to replace. Hoping the MEMCAL is okay.
aklim: ECM is electronics, 29 year old electronics. Boards age over time, especially when created on 1980's tech level. All it takes is one component or a board trace to stop working, corrode or break. I noted board traces were popped off the board, looked like wrinkles.
Team Owner
Joined: Jul 2004
Posts: 28,378
Likes: 3,261
From: Hartford WI
That was what I meant. Why did removing the memcal and replacing it make it work. Seems like you have found the problem.
Team Owner
Joined: Jul 2004
Posts: 28,378
Likes: 3,261
From: Hartford WI
Thread Starter
Drifting
Joined: Nov 2015
Posts: 1,695
Likes: 324
Finalist 2020 C4 of the Year - Unmodified
Thread Starter
Drifting
Joined: Nov 2015
Posts: 1,695
Likes: 324
Finalist 2020 C4 of the Year - Unmodified
The MEMCAL has a connector, it plugs into the ECM. For electrical connectors, often the metal they are made from burnishes (not quite rust but similar idea) and over a long period of time, the metal connection may get poor or not connect at all.
Easy fix is get that metal scraped a bit, the burnish isn't very thick. Simple method, take the connected items, pull apart then reconnect. Do this several times. This rubs the connectors and gets the metal back to normal state and connection is back to working!
Computer techs, like me, do this all the time with things like memory chips and other items to get a computer going again.
