No Communication with PCM, BCM, HVAC, ETC
12-01-2017, 09:33 PM
#1
Cruising
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No Communication with PCM, BCM, HVAC, ETC
Hello guys,
I just recently spun a rod bearing in my 99 corvette. So I parked it running in the garage and completely rebuilt the drivetrain from the ground up. Motor back to rear end. After I completed the install I went to go start the car and it turns over fine but would not start. I would get a reduced power to the engine, low fuel ( when I had well over 1/2 tank in the car), the fuel gauge would read E, the temp gauge would spike to 260, I had no fuel pressure on the rail so I jumped out the relay and the pump came on. thinking the relay was my problem I replaced it and it still does the same thing. no fuel pressure to the rail and the only way to get the pump to come on is to jump it out. So I checked my codes and I got a No Comm. code throughout everything. From PCM to HVAC to IPC and so on. I have lights in the car, driver side window and passenger window goes up and down but locks won't work. Check engine light does not light up on the dash but all the other lights do. I have checked every ground I could think and they are all still tight. The car was in a climate controlled garage its time being down. I have double checked the wiring harness and it does not seem to be pinched. I don't know if my PCM went bad or what. Even after jumping out the fuel pump to get fuel to the rail the computer would not allow the injectors to come on. I'm completely baffled and lost on what to do next. Any help to get this car back up and running would be apricated.
Thank you for your time,
Kyle
I just recently spun a rod bearing in my 99 corvette. So I parked it running in the garage and completely rebuilt the drivetrain from the ground up. Motor back to rear end. After I completed the install I went to go start the car and it turns over fine but would not start. I would get a reduced power to the engine, low fuel ( when I had well over 1/2 tank in the car), the fuel gauge would read E, the temp gauge would spike to 260, I had no fuel pressure on the rail so I jumped out the relay and the pump came on. thinking the relay was my problem I replaced it and it still does the same thing. no fuel pressure to the rail and the only way to get the pump to come on is to jump it out. So I checked my codes and I got a No Comm. code throughout everything. From PCM to HVAC to IPC and so on. I have lights in the car, driver side window and passenger window goes up and down but locks won't work. Check engine light does not light up on the dash but all the other lights do. I have checked every ground I could think and they are all still tight. The car was in a climate controlled garage its time being down. I have double checked the wiring harness and it does not seem to be pinched. I don't know if my PCM went bad or what. Even after jumping out the fuel pump to get fuel to the rail the computer would not allow the injectors to come on. I'm completely baffled and lost on what to do next. Any help to get this car back up and running would be apricated.
Thank you for your time,
Kyle
12-23-2017, 07:49 PM
#2
Instructor
Hi Kyle,
I went through a very similar rebuild recently.
Do you have a tuning device? If you can hook to your OBD II and get your VIN from your PCM, odds are that it's still good.
In my opinion, it sounds like one of just a few things:
PCM isn't hooked up
star connector isn't hooked up
Grounds aren't making good connection
RPE comes from the PCM
Fuel level comes from the PCM
Temp read by PCM
Fuel pressure is controlled by the PCM
Every symptom, to me, looks like something to do with the PCM. Yes, the PCM could have gone bad, but I don't believe much in the likelihood of that coincidence. Seems MUCH more likely that the connectors aren't in the PCM right or aren't tightened down enough, to me.
I went through a very similar rebuild recently.
Do you have a tuning device? If you can hook to your OBD II and get your VIN from your PCM, odds are that it's still good.
In my opinion, it sounds like one of just a few things:
PCM isn't hooked up
star connector isn't hooked up
Grounds aren't making good connection
RPE comes from the PCM
Fuel level comes from the PCM
Temp read by PCM
Fuel pressure is controlled by the PCM
Every symptom, to me, looks like something to do with the PCM. Yes, the PCM could have gone bad, but I don't believe much in the likelihood of that coincidence. Seems MUCH more likely that the connectors aren't in the PCM right or aren't tightened down enough, to me.