If the PCM doesn't see a return reference signal from, say, the ignition control module, will it in turn, tell the fuel pump not to pump? I've been going through the wiring diagrams trying to figure out my no start problem, and everything seems to go through the PCM. The two items don't interconnect, except throught the PCM. I get no fuel pressure, I get no spark. O.K., I got weak spark on #3 once while checking for spark. I tested several times. I only hear the fuel pump 1 time in maybe 10 key on events. No codes and all fuses and relays are good. I haven't the foggiest idea how to test the PCM. I do have a new PCM still sealed in the box and I don't want to pay the "used to be GM dealer" to flash it if I don't need it. I also don't want to pay for the tow if I don't need to.
If somebody could tell me if the PCM won't send on signals to components when it isn't receiving signals from other components, it would help me a ton!
THANKS!
Mark
2004 Cavalier LS Sport
All factory except K&N drop in filter
If your fuel pump relay is buzzing with the key on, like you said it is in the eariler post then it seems it doesnt need to see a reference voltage.
To see the inputs/outputs of the PCM, you need either a TechII or MODIS.
For whats it worth I have NEVER saw a bad ECM on ANY Cavalier or Sunfire.
- 2004 Cavalier - 124k, owned since new
Something I just noticed. The theft light will turn on for a couple of seconds then turn off when I key on. The next time it stayed on through the start attempt. The third time, it went off. 4-7 key on, it went off. I don't get it. I am seeing different stuff each time. That includes the service light and the engine light. They take turns being on.
I also get "error" on the odometer now and again.
Maybe I should just blow the thing up. Or, give up, and take it to somebody I don't really trust at the what used to be a dealership. I'm trying to decide. Two more parts (ICM then coils if nessesary), or dealer.
Snide replies accepted.
THANKS!
Mark
2004 Cavalier LS Sport
All factory except K&N drop in filter
The coils are part of the ICM.
The theft light should not stay on when cranking, this goes back to before with why is it not allowing spark/fuel. What is the ECM seeing that it isnt allowing it
I'd be willing to bet $$$ that when the theft light stayed on the FP relay wasnt clicking.
The service lamp, and engine light do on for a second during a bulb test with the key on.
I had a Cavalier with just the service lamp on, the fuse was blown for the 12V power port.....but you said all fuses are good.
- 2004 Cavalier - 124k, owned since new
The ICM can be bought seperate under a different part number.
I didn't take note of the buzzing and theft. I'll try again tommorrow.
The thing with the service light on one time and the engine light on the other, they stay on. They don't extinguish. I plugged in to see if there was a code with the service light on and no such luck. Still no codes.
Yup. All fuses good. I pulled and check the pertinent ones many times, and all in the dash were pulled and checked along with all under the hood.
I appreciate all of the head scratching. Maybe I should just go spend the big bucks and see if the "used to be dealer" still has any diagnostic equipment they can put it on.
Thanks!
Mark
2004 Cavalier LS Sport
All factory except K&N drop in filter
