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Truck will not start, need help badly....

974door

974door

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Location
Port Arthur, TX
Sorry so long, but here goes....

It all started about a month ago.

We drove the truck about 3 hours each way to a show, and everything was fine. I noticed the security light would come on for a little while, then go off. I made a few stops on the way home, everything was still fine.

Parked it for the night. Got up Sun. morning and went to move it, turned the key on, and waited for the lift pump and glow plugs to go off( like I always do) tried starting it. It would turn over and catch for just a split second.

Does it everytime. I started looking at different forums online and started changing parts. It has a new fuel filter, lift pump, o.p.s. and crank shaft sensor. Still nothing. I got it towed to the dealership to check the passlock system, and they could not find anything wrong with it when they put it on the machine.

Got it towed back home. I jacked it up, and was gonna pull the starter off to have it tested, when I looked on the firewall behind the pass. side tire and noticed a wire was broken. I jumped it and it fired right off. I spliced a new wire in and everything has been fine. Until this past monday when it did the same exact thing. I checked the wire and it was fine. I got it towed home.

I noticed about a week ago when coming up to a stop sign, the truck would kind of surge a little, like ot wanted to take off on it's own. It was also harder to start the day before it quit on me. When I got it home, I started chasing the wire that I had spliced, and it goes to the abs plug. Abs was taken off by previous owner.

I don't think that would keep it from running though. I ordered a new pmd and relocated it behind bumper, still no run. I have noticed the security light on and off over the last few weeks.

I tried to override the passlock, didn't help. We tried to hook up a scanner to it, but it said it couldn't link up. I check and it does have power to link center. Any suggestions?

Edited by TD, guys when posting a problem, do us a favor break it up some point by point, a long run on paragraph is a b1tch to read and get facts from
 
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You need to resolve the ECM issue. The scanner needs to be able to link up.

Pull the ECM and look for corrosion on the connectors. Plug everything back up and see if the scanner will connect.

One of the ports on the OBD II connector has 12volts going to it. Make sure voltage is present. Check all fuses - sometimes the OBD II connector will share a circuit with the cig lighter or the horn.
 
We pulled it out and looked at all the plugs. They all looke fine to the naked eye. We plugged it back in, and nothing. I used a schematic from one of the parts house manuals, and it said the orange wire was the hot wire for the data link up. I used a test light and it was good at the data link hookup. I am looking for a set of good wiring schematics for this truck if anybody knows where i can get some, it is greatly appreciated. Just out of curiosity, should the ecm be in the dash on the pass. side?
 
yep behind the glove box...

Also there are about 10 main grounds that the vehicle NEEDS to operate... they coorode up and need to be taken off, wire brushed and re-attached.

go over EVERY ground, clean em all up, Ground wires cab to frame, engine grounds, negative batts, one next to PS battery, a few by the firewall, a bunch on the intake studs... CLEAN EM ALL.

Have you ever replaced your PMD with a NEW Remotely located one? Check out HeathDiesel for the bulletproof one with a 7 year warranty.
 
Check all grounds, and also check EVERY fuse in the vehicle for corrosion... check PCM harness for cooroded pins too. Do some searches at the place to find a list of grounds, there are about 10-12 that need to be good. Come and go problems are usually grounds/corrosion.
 
ABS when it goes bad kills comms to computer, I haven't figured out why yet, but my 98 Burb has bad ABS, which kills comms to computer, so PCM goes to limp fuel mode, yours may be setting VTD module and killing power to fuel solenoid thinking it is being stolen.

At ABS motor/control unplug front plug and see if you get scanner to talk to PCM, if scanner can't talk, neither can the PCM communicate with the engine, you need to find out why you haver comms loss 1st, possibly a wire in area you found cut one has good insulation but bad wire inside so you can't see the intermittent break. PCMs rarely go bad, I had one go completely submerged during Katrina in salt water that was fully functional afterward.
 
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Turbine Doc said:
ABS when it goes bad kills comms to computer, I haven't figured out why yet, but my 98 Burb has bad ABS, which kills comms to computer, so PCM goes to limp fuel mode, yours may be setting VTD module and killing power to fuel solenoid thinking it is being stolen.

At ABS motor/control unplug front plug and see if you get scanner to talk to PCM, if scanner can't talk, neither can the PCM communicate with the engine, you need to find out why you haver comms loss 1st, possibly a wire in area you found cut one has good insulation but bad wire inside so you can't see the intermittent break. PCMs rarely go bad, I had one go completely submerged during Katrina in salt water that was fully functional afterward.
Click to expand...

The abs is no longer on the truck. The plugs are still there however. On the plug with only two wires going to it, should there be power to one of them. The purple wire is the one I am talking about. It is the one that was cut at the fire wall. It has no power at the end of the plug where it went to the abs box, bit the ground side still shows a ground.
 
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In my opinion, not good enough to stick an ohm meter on the grounds. Need to take them apart and clean them all. Matt's note about the fuses - if you check my thread on 'melange of DTC codes', it tells a tale that is most-likely linked to bad connections, bad wiring, etc. I probably put $350 worth of parts in I didn't need (except the glows, it needed those!). I try to comfort myself saying that those parts were pretty old, and probably needed to be replaced... but still...

Best place to get genuine GM service manuals is Helm. Costs about $150. Indispensable, very accurate, although a HUGE amount of data, sometimes hard to find things, but keep plugging away - it's in there!

All the best,

Rob :)
 
Your meter may show the ground being good even when they aren't up to the task. If you see a high resistance (> 1/2 Ohm or so) the connection IS bad. But, unfortunately, the opposite isn't always true.
Every ground connection should be cleaned and tightened annually (which is overkill, btw, but will prevent future ground problems). Heat and vibration work on the connections and once just a bit loose they will arc or corrode causing problems that seem totally unrelated. Same goes for the battery connections.
Even if a bad ground isn't your problem you will be ahead of the game knowing that they are all clean and tight. A Dremel tool with a wire brush really cleans em up. I also put NoAlOx (Home depot, etc) on every connection to prevent dissimilar metals from eating each other. NoAlOx is a trade name and the store you may have anticorrosion stuff under a different name.
 
974door said:
The abs is no longer on the truck. The plugs are still there however. On the plug with only two wires going to it, should there be power to one of them. The purple wire is the one I am talking about. It is the one that was cut at the fire wall. It has no power at the end of the plug where it went to the abs box, bit the ground side still shows a ground.
Click to expand...

The purple one is the comm link, on mine I have it unplugged or I can't use my scan tool, so you may need to re-disconnect it
 
Sorry for the quick hijack, But curious. Will ABS problems have the same or similar effect in an OBD 1 truck? I've no problems now, but it seems something that could be easily overlooked in the future......thanks
 
good ????

lets step back a bit has this been an issue since you owned the vehicle, or are you problems a recent occurance??

on mine there is some fault in ABS when plug you see disconnected in pic is plugged in all sorts of things happen and I get a U100 (no communication code) I don't know what happens with all plugs removed, alas I'm literally headed out the door for a week so won't be able to contribute much in way of trying different things.
 

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We may be dealing with 2 separate issues and youv'e uncovered the ABS issue sidetracking from the no start/dies one, security issues sounds like theft deterrrent module, have you swapped PCMs recently, could be PMD issue as well. OPS in a OBD-II truck won't shut it down as you have 2 paths of power vs OPS in OBD-I.
 
Turbine Doc said:
Replaced with new or used, on cooler plate or just any piece of metal, who's kit SSD's, where is your driver grounded on IP or off, did you remember to put in the resistor?
Click to expand...

It is a new one from dieselcare.net. It is on a cooler behind the front bumper with a new #9 resistor in it. The ground is still on the ip.
 
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