C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

ECM Replacement

Old Sep 9, 2004 | 10:28 AM
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Default ECM Replacement

I am about to replace the ECM on my 1992 LT1. Do I only need to unbolt the old one and disconnect the wires and then install the new one. Or, does the ECM need to be programmed? Is there a chip that needs to be transferred from the old one to the new one?
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Old Sep 9, 2004 | 10:34 AM
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You need to keep the original MemCal (EPROM), that is under a cover on the under-side of the ECM, to put in the new ECM.

First step, disconnect the negative battery terminal.
Then, unbolt the ECM and take the connectors off.
Then, remove the original MemCal and install in the new ECM.
Finally, install the new ECM.

Tom Piper
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Old Sep 9, 2004 | 12:08 PM
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Default ECM replacement.

Thank you. I was getting a nonstart (cranking but fuel shutdown) with a code 41 and the ASR service light on. This morning I cooled the ECM (with ice in a zip lock bag) and the car started immediately with no trouble lights on. So I figured I would just replace the ECM. Any opinions?
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Old Sep 9, 2004 | 03:00 PM
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it would be great if you had a known good memcal (chip) to try. I just battled that and after 3 ecm's and 1 ccm found both my memcals were fried.
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Old Sep 9, 2004 | 06:01 PM
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Originally Posted by c2c4c6
Thank you. I was getting a nonstart (cranking but fuel shutdown) with a code 41 and the ASR service light on. This morning I cooled the ECM (with ice in a zip lock bag) and the car started immediately with no trouble lights on. So I figured I would just replace the ECM. Any opinions?
Have same problem as you...hard starting when hot.
When I get the ASR light on, I pull the key out and re-insert. Sometimes I have to do it two or three times before ASR is not lit.
Once ASR light is not lit , Car starts up fine.
I also changed out my ECM and it helped for a month or two before problem came back. May have to look for new chip.
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Old Sep 9, 2004 | 10:09 PM
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Originally Posted by c2c4c6
Thank you. I was getting a nonstart (cranking but fuel shutdown) with a code 41 and the ASR service light on. This morning I cooled the ECM (with ice in a zip lock bag) and the car started immediately with no trouble lights on. So I figured I would just replace the ECM. Any opinions?
To fully prove to yourself it is the ECM, heat the ECM when cool with a heat gun (hair drier) on the top side with the ignition on, engine off. If the ECM, the ASR light will come with the Sys and Security light flashing. Should only take one to two minutes with the heat gun.
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