1992 Corvette Intermittent no start
Thread Starter
5th Gear
Joined: May 2023
Posts: 5
Likes: 0
1992 Corvette Intermittent no start
Hey, this is my first time on this forum so I'm not sure if this subject has been talked about but I have a 1992 corvette with 58000 miles on it with an odd issue. It occasionally has a crank no start condition with the SYS, Security and Service ASR but I can get the car started by wiggling the ECM wires. The car will drive perfectly with no lights until for some reason when I turn right they come back on until I straighten the wheel. I pulled these codes
MODULE 1: H41, H54, H74
MODULE 4: ERR or --
MODULE 9: ERR or H72
Modules 4 and 9 change at times to -- and H72 respectively.
MODULE 1: H41, H54, H74
MODULE 4: ERR or --
MODULE 9: ERR or H72
Modules 4 and 9 change at times to -- and H72 respectively.
Thread Starter
5th Gear
Joined: May 2023
Posts: 5
Likes: 0
Drifting
Joined: Jun 2020
Posts: 1,355
Likes: 396
From: Northwest Ohio
Sounds like comm issues. You could also have bad solder joints inside the ECM or a loose PROM or bad wiring.
I would start by unplugging the harnesses from the ECM and making sure the connectors/connections look good and re seat them all. Then pull and reseat the PROM.
If the issue continues you need to check wires carefully (and grounds as suggested). You could use the FSM to troubleshoot the relevant circuits.
Your ECM may be destined for a trip to SIA electronics for a reflow…unfortunately price has doubled since I had my 93 done (same ECM).
The thing that concerns me is the fact it’s not just losing ECM to CCM comms, but CCM to EBTCM comms. That’s what would happen when my ECM got hot and it was failing (it would introduce noise on the line). Again you may have a simple short though that could cause similar issues..FSM is your friend.
I would start by unplugging the harnesses from the ECM and making sure the connectors/connections look good and re seat them all. Then pull and reseat the PROM.
If the issue continues you need to check wires carefully (and grounds as suggested). You could use the FSM to troubleshoot the relevant circuits.
Your ECM may be destined for a trip to SIA electronics for a reflow…unfortunately price has doubled since I had my 93 done (same ECM).
The thing that concerns me is the fact it’s not just losing ECM to CCM comms, but CCM to EBTCM comms. That’s what would happen when my ECM got hot and it was failing (it would introduce noise on the line). Again you may have a simple short though that could cause similar issues..FSM is your friend.
Thread Starter
5th Gear
Joined: May 2023
Posts: 5
Likes: 0
Sounds like comm issues. You could also have bad solder joints inside the ECM or a loose PROM or bad wiring.
I would start by unplugging the harnesses from the ECM and making sure the connectors/connections look good and re seat them all. Then pull and reseat the PROM.
If the issue continues you need to check wires carefully (and grounds as suggested). You could use the FSM to troubleshoot the relevant circuits.
Your ECM may be destined for a trip to SIA electronics for a reflow…unfortunately price has doubled since I had my 93 done (same ECM).
The thing that concerns me is the fact it’s not just losing ECM to CCM comms, but CCM to EBTCM comms. That’s what would happen when my ECM got hot and it was failing (it would introduce noise on the line). Again you may have a simple short though that could cause similar issues..FSM is your friend.
I would start by unplugging the harnesses from the ECM and making sure the connectors/connections look good and re seat them all. Then pull and reseat the PROM.
If the issue continues you need to check wires carefully (and grounds as suggested). You could use the FSM to troubleshoot the relevant circuits.
Your ECM may be destined for a trip to SIA electronics for a reflow…unfortunately price has doubled since I had my 93 done (same ECM).
The thing that concerns me is the fact it’s not just losing ECM to CCM comms, but CCM to EBTCM comms. That’s what would happen when my ECM got hot and it was failing (it would introduce noise on the line). Again you may have a simple short though that could cause similar issues..FSM is your friend.
Drifting
Joined: Jun 2020
Posts: 1,355
Likes: 396
From: Northwest Ohio
So I actually had to get another ecm from ecu exchange since the one it had fried the injector circuit probably cause it had a short in a injector wire which I replaced. The ecm i got could be bad too like you said. You also mentioned that when it gets warm it could pose issues, sometimes mine can go a whole drive without the lights coming on and will always start. I'll start by checking the wires in the area and I'll keep you guys posted, thank you so much for the replies.
It sounds like wires/connector, if truly disturbing the wires has an effect. You’ll need to inspect the connectors and pins carefully and lookup which wires/pins are associated with comm specifically…
The connectors have been on/off before and if wiring has been damaged by mice etc(?) that could be at play.
Thread Starter
5th Gear
Joined: May 2023
Posts: 5
Likes: 0
that’s good back info…why was the injector wire shorted?
It sounds like wires/connector, if truly disturbing the wires has an effect. You’ll need to inspect the connectors and pins carefully and lookup which wires/pins are associated with comm specifically…
The connectors have been on/off before and if wiring has been damaged by mice etc(?) that could be at play.
It sounds like wires/connector, if truly disturbing the wires has an effect. You’ll need to inspect the connectors and pins carefully and lookup which wires/pins are associated with comm specifically…
The connectors have been on/off before and if wiring has been damaged by mice etc(?) that could be at play.
Thread Starter
5th Gear
Joined: May 2023
Posts: 5
Likes: 0
Connector checking
that’s good back info…why was the injector wire shorted?
It sounds like wires/connector, if truly disturbing the wires has an effect. You’ll need to inspect the connectors and pins carefully and lookup which wires/pins are associated with comm specifically…
The connectors have been on/off before and if wiring has been damaged by mice etc(?) that could be at play.
It sounds like wires/connector, if truly disturbing the wires has an effect. You’ll need to inspect the connectors and pins carefully and lookup which wires/pins are associated with comm specifically…
The connectors have been on/off before and if wiring has been damaged by mice etc(?) that could be at play.
Those are some of them but they all look the same. Unless that goo inside has anything to do with it.
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