NO Start
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Truck started up well this morning but kept dying again. And I was also getting check engine light. Once truck got really warm it seemed to run fine. I drove it about 3 miles with no check engine light.
Mike, can I keep that option open with the IDM?
Mike, can I keep that option open with the IDM?
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Senior User
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I'm back! Still fighting my check engine intermittent problem.
Got a question for someone who can help me out.
Couple of things.
1. I tested the MAP sensor harness and the Vref is ohming out at 980 and should be > 1000. Is this a problem? When I unplug MAP and drive truck around I still get the stalling.
The volts and the ohm reading going from the 42 pin connector to the pigtail all meet spec though.
2. I tried to eliminate some of the sensors by unplugging them and then running my truck to see if I still got the severe stalling. I disconnected MAP, EBPS, AP, and BARO, one by one, but still had the same problem.
3 I ohmed all wires and they appear good. The only problem I seem to have is when I test for voltage at the PCM connector at pins 96 to91, 95to91 and 48 to 91, they should all have voltage. I get none, with key on.
I unpluuged the PCM connector from the firewall to test. Should I be testing it another way? Does the voltage come from the PCM or from the IDR?
Got a question for someone who can help me out.
Couple of things.
1. I tested the MAP sensor harness and the Vref is ohming out at 980 and should be > 1000. Is this a problem? When I unplug MAP and drive truck around I still get the stalling.
The volts and the ohm reading going from the 42 pin connector to the pigtail all meet spec though.
2. I tried to eliminate some of the sensors by unplugging them and then running my truck to see if I still got the severe stalling. I disconnected MAP, EBPS, AP, and BARO, one by one, but still had the same problem.
3 I ohmed all wires and they appear good. The only problem I seem to have is when I test for voltage at the PCM connector at pins 96 to91, 95to91 and 48 to 91, they should all have voltage. I get none, with key on.
I unpluuged the PCM connector from the firewall to test. Should I be testing it another way? Does the voltage come from the PCM or from the IDR?
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Jim, you around?
I untaped all the wires from the PCM, IDM and the big connector to the fuse box. I looked at all the wires and put everything back together. I loosened fuse box and turned upside down and looked at all the wires. Nothing looked bad.
Truck no start.
Again when I check volts going to signal(B) of IPR I am back to 1.3 volts. I checked the volts coming out of the pins on the 42 pin connector and it is 1.3 volts. So, it isn't a connector problem. Could it be an ICP problem and the PCM is sending the 1.36 volt signal with key on engine off? I gotta get this fixed.
So, do I have a bad ground in the PCM? How is the PCM grounded. I know there is a small ground wire coming off the PCM harness that goes to the frame.
What else should I do now?
I untaped all the wires from the PCM, IDM and the big connector to the fuse box. I looked at all the wires and put everything back together. I loosened fuse box and turned upside down and looked at all the wires. Nothing looked bad.
Truck no start.
Again when I check volts going to signal(B) of IPR I am back to 1.3 volts. I checked the volts coming out of the pins on the 42 pin connector and it is 1.3 volts. So, it isn't a connector problem. Could it be an ICP problem and the PCM is sending the 1.36 volt signal with key on engine off? I gotta get this fixed.
So, do I have a bad ground in the PCM? How is the PCM grounded. I know there is a small ground wire coming off the PCM harness that goes to the frame.
What else should I do now?
Post Fiend
Joined: Dec 2010
Posts: 10,121
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From: Orrville, Ohio
There are several grounds for the PCM on the inside of the driver side foot well too. There should be three or so of them behind the emergency brake pedal assembly. You'll probably have to remove the pedal to get to them, but it is just three nuts to remove the whole assembly.
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Not sure I am getting anywhere, but here is the latest.
Truck starts and idles as good as if new.
But, I now have the check engine light on almost constantly. I think this is good.
It runs good till it gets good and warmed up, then at times it seems like the engine is revving good but the transmission isn't working right. I had the tranny rebuilt 5k miles ago. Good thing I don't need or use this truck much. I'd have it in the shop.
Someone mentioned on another thread about the PCM having a ground clip on it. I have only one ground to the PCM and that is the black wire that goes from the PCM connector to the frame under the hood.
Does anyone know about this? 95 f 350 crew cab
Truck starts and idles as good as if new.
But, I now have the check engine light on almost constantly. I think this is good.
It runs good till it gets good and warmed up, then at times it seems like the engine is revving good but the transmission isn't working right. I had the tranny rebuilt 5k miles ago. Good thing I don't need or use this truck much. I'd have it in the shop.
Someone mentioned on another thread about the PCM having a ground clip on it. I have only one ground to the PCM and that is the black wire that goes from the PCM connector to the frame under the hood.
Does anyone know about this? 95 f 350 crew cab
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I know someone can help me again! Jim?
My truck seems to fun fine right now. I drove it 10 miles and no real problems, but the check engine light is on constant except for once this morning,
I think this will solve my problem.
When I started truck I was watching the amp gauge and normally it goes way down until the glow plugs switch off, but today it didn't hardly move when I started it and the glow plugs cycled off and was stable and "no check engine light". I drove truck and CEL came on, but truck ran fine.
So, I start it up again and amp gauge goes way down until glow plugs shut off, then amp gauge came up and CEL came back on. Truck still runs fine though.
So, I ohmed the glowplug wires and everything was good to the 42 pin connector.
I checked voltage at A and B of glowplug connector and A was 12 plus volts and B was 1.36 volts. That is the same voltage I was getting when I was having a no start conditon only that voltage was on the IPR harness. It almost looks like the PCM is now sending a 1.36 volt signal through the glowplug harness. Am I wacko?
No one has been able to tell me about PCM grounds. I have one ground wire on the PCM connector and that is it. Should the PCM itself have a ground on it?
My truck seems to fun fine right now. I drove it 10 miles and no real problems, but the check engine light is on constant except for once this morning,
I think this will solve my problem.
When I started truck I was watching the amp gauge and normally it goes way down until the glow plugs switch off, but today it didn't hardly move when I started it and the glow plugs cycled off and was stable and "no check engine light". I drove truck and CEL came on, but truck ran fine.
So, I start it up again and amp gauge goes way down until glow plugs shut off, then amp gauge came up and CEL came back on. Truck still runs fine though.
So, I ohmed the glowplug wires and everything was good to the 42 pin connector.
I checked voltage at A and B of glowplug connector and A was 12 plus volts and B was 1.36 volts. That is the same voltage I was getting when I was having a no start conditon only that voltage was on the IPR harness. It almost looks like the PCM is now sending a 1.36 volt signal through the glowplug harness. Am I wacko?
No one has been able to tell me about PCM grounds. I have one ground wire on the PCM connector and that is it. Should the PCM itself have a ground on it?
Hotshot
Joined: Feb 2009
Posts: 10,410
Likes: 77
From: Plankinton, SD
I stole this from Jim out of another thread. He mentions the grounds. This is in the buzzing thread of fishmanndotcom's.
I agree with the above. One addition test is required and that is to measure the resistance on the IDM relay socket, 6 o'clock position to the PCM pin #70. It should be close to zero ohms. My other advice is to check the PCM grounds. You already checked 1 and there are 5 others. On my rig they are located between the radiator support and the drivers side battery. Four small wires and a bigger flat strap held down by two bolts. Unless you have had these off in the past for whatever reason they are probably OK but a good visual inspection would be in order.
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I agree with the above. One addition test is required and that is to measure the resistance on the IDM relay socket, 6 o'clock position to the PCM pin #70. It should be close to zero ohms. My other advice is to check the PCM grounds. You already checked 1 and there are 5 others. On my rig they are located between the radiator support and the drivers side battery. Four small wires and a bigger flat strap held down by two bolts. Unless you have had these off in the past for whatever reason they are probably OK but a good visual inspection would be in order.
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