Help. Electrical Grimlins

[brandon's Z]

I have what I am considering a weird one. I have recently purchased my second 1990 ZR-1 car 103.
This car was purchased at auction and I have been running the bugs out of it. It ran like SH## when I got it and now is running really well with one big issue that happen often.

Sometimes when driving the car it will have a single slight miss and then the Speedometer and AC both will quite. Then the SES light comes on and no secondary’s. The “Sys” Light also flashes indicating a code.

I ran codes the first time and got a 21,42,45,56,65. I put several miles on it while it would run great then go into the gremlin mode.

I cleared the codes (I have a OTC SPX Genies) and the car will still have this problem, but the ALDL will stops working and does not show any codes or even communicate.

When it is having this problem the scanner cannot communicate with the car at all.

Everything reads great then the gremlin appears and the scanner loses communication. I don’t have access (lost currently) my FSM. Any of the gurus around have any thoughts on why the ALDL would work intermittently like I have?

[gbrtng]

Classic flakey ECM problem - see if you can find a known good one to swap for a trial repair.
Someone in your area should be able to help.

[GOLDCYLON]

Concur... if you can swap the ECM from your other 90 see if that makes these problems go away.

[batchman]

Sometimes when driving the car it will have a single slight miss and then the Speedometer and AC both will quite. Then the SES light comes on and no secondary’s. The “Sys” Light also flashes indicating a code.

Similar things happens to me when my battery is in a marginal state. Easier swap than the ECM if it's age/condition are not known.

Good luck,
- Jeff

[brandon's Z]

This is the second ZR-1 I have owned, but I don't still have the first. Anyone have a ECM that they could loan? I am in Southern Indiana

Thanks
Brandon

[brandon's Z]

Also is the ZR-1 the same computer as base model vette? I would assume not since we are not batch fire and 16 injectors.

[GOLDCYLON]

Also is the ZR-1 the same computer as base model vette? I would assume not since we are not batch fire and 16 injectors.

No it is NOT the same

[tccrab]

No it is NOT the same

I concur with the cycloptic moderator.
The ECM only shares the case with the ZR1, it may look the same, but the guts are entirely different.
Do not let anyone tell you different.
Been there, done that.
Save you the time and the exasperation.

'Crabs

[brandon's Z]

Anyone know of where I could burrow a ECM?

Thanks
Brandon

[92whiteZ]

Brandon,

i have a Genisys too and found it sort of interfaces with the car's systems but not completely. Have you tried someone's Tech 1 to really trouble shoot? Mine has been way more helpful that my Genisys has even been.