ANPLUSHF
New Member
I am the brother of Harqobispal, who actually shares the EXACT same problem as myself.
Here is a link to his thread.
http://dieseltowingresource.com/showthread.php?t=6738&highlight=light
I have been trying to save myself some cash by letting him do most of the part replacement. He has still not CURED his problem but he claims it doesn't do it often enough to warrant any more money.
My symptom, has unfortunately become more frequent, even after my attempts to fix it.
I performed the following tests/repairs:
-Cleaned Grounds and ran new ones to the PCM.
-Checked splices in wire harness (redid some). All had virtually no resistance to begin with
-Checked all involved fuses (ECM, ENG-1, ECM-B)
-Cleaned contacts and wiring to underhood fuse box
-Power to PCM is good at all times.
-Ground to PCM is good at all times.
-Ignition switch appears to be functioning properly (power at appropriate places at appropriate times)
My PMD is still on the pump, but looking through the GM service manual and understanding somewhat how the system works, i don't think it is PMD related.
It is like the PCM just looses power, the strange part is it does not. I have been carrying around a multimeter so i can check power to the PCM as soon as the stall happens. It has both Battery and Ignition power, but no output to fuel pump relay or glow plugs. The strange thing is if you leave the key in run position for a while the power to the fuel pump will "stutter" on. I will have to take a short video of it to explain it but if you have the meter hooked up to output on the PCM it spikes to 8 then 0 then 9.5 then 0, but at completely random time/temp, like a bad connection is making contact again.
Again like my brother's problem after some random time (10 secs to 10 mins) you cycle the key, wts light cycles pump turns on and bam starts right up.
I do have a HP4 heath PCM in mine,not sure what difference this makes, but thought i would mention it.
Also worth noting was that the other day while doing some testing just idling it in my driveway till it quit, the alternator burned up, literally. The thing was smoking like crazy when i opened the hood and you could smell the burning electronics. My worry now is that this has something to do with my problem. I am going to check for a draw on the system possibly causing all this.
One thought i had is that possibly the PCM has a fail safe that shuts it off when it has a problem (over voltage, under voltage, bad ground) and shuts down for a predetermined time?
Not sure if that is so, but i have no idea of the logic inside the computer. Also could a bad sensor cause it to do this? I tried unplugging a few after the third stall in 10 miles, on the way back home tonight after work. All they seem to do is put the tranny in limp mode.
Logic also tells me it may be heat related. Could a bad temp sensor cause shutdown with no code or SES? Fuel temp sensor? If i unplug these do they go to baseline like most sensors, so i can run it in baseline to see if it stalls still?
Any suggestions?
Here is a link to his thread.
http://dieseltowingresource.com/showthread.php?t=6738&highlight=light
I have been trying to save myself some cash by letting him do most of the part replacement. He has still not CURED his problem but he claims it doesn't do it often enough to warrant any more money.
My symptom, has unfortunately become more frequent, even after my attempts to fix it.
I performed the following tests/repairs:
-Cleaned Grounds and ran new ones to the PCM.
-Checked splices in wire harness (redid some). All had virtually no resistance to begin with
-Checked all involved fuses (ECM, ENG-1, ECM-B)
-Cleaned contacts and wiring to underhood fuse box
-Power to PCM is good at all times.
-Ground to PCM is good at all times.
-Ignition switch appears to be functioning properly (power at appropriate places at appropriate times)
My PMD is still on the pump, but looking through the GM service manual and understanding somewhat how the system works, i don't think it is PMD related.
It is like the PCM just looses power, the strange part is it does not. I have been carrying around a multimeter so i can check power to the PCM as soon as the stall happens. It has both Battery and Ignition power, but no output to fuel pump relay or glow plugs. The strange thing is if you leave the key in run position for a while the power to the fuel pump will "stutter" on. I will have to take a short video of it to explain it but if you have the meter hooked up to output on the PCM it spikes to 8 then 0 then 9.5 then 0, but at completely random time/temp, like a bad connection is making contact again.
Again like my brother's problem after some random time (10 secs to 10 mins) you cycle the key, wts light cycles pump turns on and bam starts right up.
I do have a HP4 heath PCM in mine,not sure what difference this makes, but thought i would mention it.
Also worth noting was that the other day while doing some testing just idling it in my driveway till it quit, the alternator burned up, literally. The thing was smoking like crazy when i opened the hood and you could smell the burning electronics. My worry now is that this has something to do with my problem. I am going to check for a draw on the system possibly causing all this.
One thought i had is that possibly the PCM has a fail safe that shuts it off when it has a problem (over voltage, under voltage, bad ground) and shuts down for a predetermined time?
Not sure if that is so, but i have no idea of the logic inside the computer. Also could a bad sensor cause it to do this? I tried unplugging a few after the third stall in 10 miles, on the way back home tonight after work. All they seem to do is put the tranny in limp mode.
Logic also tells me it may be heat related. Could a bad temp sensor cause shutdown with no code or SES? Fuel temp sensor? If i unplug these do they go to baseline like most sensors, so i can run it in baseline to see if it stalls still?
Any suggestions?
