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04 Grand Prix No crank signal
- Nandor69
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Topic Author
- Offline
- Senior Member
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8 years 6 months ago - 8 years 6 months ago #7386
by Nandor69
04 Grand Prix No crank signal was created by Nandor69
I thought this was kind of amusing so I wanted to post this. There is a shop I do diagnostic work for and while I was there finishing up a 92 Sonoma that the starter constantly cranked while the battery was connected and also didn't have injector pulse the owner wanted me to look at this 04 Pontiac.
The back story is, a guy working there did this: the crank sensor was replaced, the ICM was replaced with a used one, PCM was replaced with a used one. Still no crank signal. He had wiring harness torn apart, the fuse box out and the PCM back out. And something weird going on with the ground cable.
So I go look at it. First I checked the WHT/BLK wire at the crank sensor for 12v power. I had 0v. Then I checked voltage at ICM on the same wire. 0v. Then I checked the pink wire on the ICM to see if it had power, 0v. The ICM gets its power from the ELEK IGN FUSE 24 15A. No power on either side of that fuse. So I pull up the Power Distribution diagram and see that the ELEK fuse gets its power from P/TRAIN RELAY 40. So I Check for power at pins 30 and 85. 12v. I then pushed the relay in just far enough so I could touch pin 86 with my test light to ground. The relay clicks and a couple other things come alive. I have the dude crank it and it starts.
My next step was to go to the PCM and check pin 24 (brown wire) on the blue connector. This is the pin that grounds the control side of the P/TRAIN relay. With the key off I had 2v and key on I had close to 0v.
The brown wire takes a pretty simple path across the front of the engine to the fuse block so I started wiggling the harness until I saw the voltage start to jump up and down. I found a break in the brown wire in the harness right by the engine mount were it had rubbed through.
Fixed the break in the wire by soldering it back together and everything was fine. The owner came over to check on it and I showed him what was wrong. He was pissed. All together it took about 45 minutes to fix. I left it the other guy to put back and fix all the other crap he had torn apart. Got paid for both jobs and told him to call me when he needs me.
The back story is, a guy working there did this: the crank sensor was replaced, the ICM was replaced with a used one, PCM was replaced with a used one. Still no crank signal. He had wiring harness torn apart, the fuse box out and the PCM back out. And something weird going on with the ground cable.
So I go look at it. First I checked the WHT/BLK wire at the crank sensor for 12v power. I had 0v. Then I checked voltage at ICM on the same wire. 0v. Then I checked the pink wire on the ICM to see if it had power, 0v. The ICM gets its power from the ELEK IGN FUSE 24 15A. No power on either side of that fuse. So I pull up the Power Distribution diagram and see that the ELEK fuse gets its power from P/TRAIN RELAY 40. So I Check for power at pins 30 and 85. 12v. I then pushed the relay in just far enough so I could touch pin 86 with my test light to ground. The relay clicks and a couple other things come alive. I have the dude crank it and it starts.
My next step was to go to the PCM and check pin 24 (brown wire) on the blue connector. This is the pin that grounds the control side of the P/TRAIN relay. With the key off I had 2v and key on I had close to 0v.
The brown wire takes a pretty simple path across the front of the engine to the fuse block so I started wiggling the harness until I saw the voltage start to jump up and down. I found a break in the brown wire in the harness right by the engine mount were it had rubbed through.
Fixed the break in the wire by soldering it back together and everything was fine. The owner came over to check on it and I showed him what was wrong. He was pissed. All together it took about 45 minutes to fix. I left it the other guy to put back and fix all the other crap he had torn apart. Got paid for both jobs and told him to call me when he needs me.
Last edit: 8 years 6 months ago by Nandor69.
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