Dealer Couldn't Fix - PCM & MAP Issue

[Texas330]

Had our '03 1500 in the shop last month. Truck would intermittently shutter on the road then die totally. Stop on side of road for a couple seconds and it would re-start. Dealer eval pointed to the PCM - replaced. Two days later the cycle repeated. Dealer stated something else is tripping and/or shorting-out the PCM. They kept the truck for a month and could not find the cause. Their workaround to keep the truck running - not connecting the MAP. They said whenever the MAP (or all other PCM-related components) were connected to the PCM simultaneously, the PCM would die. So for now, we are driving with the MAP off (CEL on of course). Naturally, the truck shutters a bit on a cold start or from a starting position as its adjusting to the fuel/air mix. Once on the road, it runs like a horse.

Here's a quick list of insp points from the dealer's worksheet: "Replaced sensors on both 5-volt circuits, swapped known good coils/plugs, PDC, bypassing alternator, compressor, pressure switches, overlaying wires, thorough insp of harness & grounds, 2nd replacement of PCM - cause never isolated." It's not listed, but they told me they checked the NSS as well just in case.

Brief background: Got the truck in Nov '15. Right away - new fuel pump. Then this past Dec '17, my son said "no heater". At some point he lost all coolant - failed radiator. New radiator installed, then one week later, water pump failed - overheated & towed. Got new water pump, T-stat, and hoses in Dec '17. Shortly after that is when this whole issue started with the PCM shutting the truck down. Does this scenario give you experts any clues? I sure would like to get the MAP installed again, but not at the risk of blowing the PCM if I can help it. Thanks in advance everyone.

 

[fastf]

Sounds like this dealer is what is called a parts changer.Get with Skyramman he knows about 3rd gen computers one of the good guys that will try to help.

 

[Burla]

I had an unfixable fault once, it was a ***** to find it, but it turns out a guy who installed a step drilled through a wire, and that was all it took to fry by transfer case motor repeatedly. They had to keep paying for it because of the dealer warranty thing, and not til they decided to replace everything downstream did they find it. Something is shorting out the pcm, you need to find it. Check egr as well. My money it is a ground wire somewhere. what did the codes say

 

[Demon-HeMi]

run new wires to the pcm from the map sensor? id be trying that, or id go to another dealer and let them try to find it, maybe go to a junk yard and pull an engine harness and try changing it out

 

[Texas330]

Thanks guys. Not sure on the codes. Apparently they needed their equip to read the codes because my simple OBDII doesn't even want to speak to the truck. But the service mgr has his own '03 on-site. After about 3 weeks into all of this, he agreed to let them cannibalize off his working truck to test several parts one-by-one. At least that's what they (and he) told me. The tech also took the truck to another dealer in the city to have it evaluated. But like you said, time is money, and I know that even though they had it for over 4 weeks, they didn't actually "work" on it for 4 weeks straight. I suspect I will have to do a very careful inch-by-inch eval of everything exposed. My fear is that this never happened until my son had those two overheating episodes. I can't help but wonder if something, even a wire buried somewhere, didn't get damaged from the heat or something. But I'll continue to look. I appreciate the input guys. Keep 'em coming if you have them. I'm not quite ready to give up on this truck yet. She's a bit aged, but still pretty to look at. Other than this current issue, she still feels nice in the seat when you give her some gas.

 

[fastf]

LIke Demon-Hemi said I would be looking for another dealer that acutally has a mechanic instead of a parts changer.Here in Georgia they are called many names shade tree mechanic,Jack Leg mechanic or the glorified parts change take your pick you might just have one in your area.

 

[MatthewGoff]

Did you ever get it worked out? I have about the same problem, but we’ve put 2 ecms in and now the mechanic says my truck won’t run with the map sensors plugged in. This is an electrical shop working on it and it has been there almost 3 weeks. I’m up to $850 so far with the computer and all the diagnostician and programming the computer.