Gauges wouldn't be a problem but your right id just rather fix what i have. Problem is if a Dodge dealership can't fix it i sure can't. Literally every single sensor, fuse and relay has been replaced with brand new Mopar parts along with the PCM. Plus you guys on here have given me a wealth of information to go on, but nothing has worked. I do believe i just happen to be one of the unlucky one's to get that unstoppable gremlin the dealership spoke of.

 

Something is getting hot, and failing. Since they replaced pretty much everything..... I would suspect a bad wire in the harness somewhere. Will it start back up after it dies? Or does it need to cool for a bit first?

 

The dealership said it would run perfectly for about an hour or so then shut down. When they tried to restart it the odometer would throw the NO BUS code. So they immediately would put one of their test PCM units in and it wouldn't start and throw the same code. I was told by my shop teacher there is a 5v wire that is notorious for getting hot and shutting the PCM down and it usually is the one that runs from the throttle positioning sensor to the PCM, i believe he said it was a purple/white wire? He said the bad part about it is that particular wire cannot be replaced or spliced into or it'll make matters worse so there is really no way of fixing the problem unless you replace the complete wiring harness. He also said that particular wire also will tell the PCM that the crankshaft positioning sensor is bad as well as the cam sensor when there are actually not bad.

 

If you replace the wire with one of the same gauge, and use the correct terminals on the ends, replacing it shouldn't be an issue. It's a 5 volt supply. So long as the sensor gets it's five volts, it shouldn't care HOW it gets there.

The "No Bus" error IS a problem on the 5 volt supply circuit to the various sensors though. Trouble is, that is pretty much ALL of them. Isolating which one is the problem is the fun part.

When the problem presents itself, turn off ignition, unplug a sensor. Try and start the truck. That should help determine which sensor/circuit is causing the issue.

 

That was the first thing i did when you suggested it before (i think it was you?).
Maybe the dealership just didn't want to mess with it because they knew i couldn't pay a $1000 bill for the hours it would take them to trace it down.

 

That does seem familiar.

And thinking about it some more...... Not sure just unplugging sensors will even matter. Real possibility that you will have to trace down EACH 5 volt circuit, and see if you can find something that looks like it might be a problem. If it's a short to ground, then there should be bare wire touching something that grounds it out.... may or may not be easy to see.

My dads old Buick had an intermittent charging issue..... turned out it was a broken wire INSIDE the insulation. Inspection showed nothing, but, wiggle the wire, and the alternator would drop out. That was fun to find.......

 

I'll spend a few more days on it and if i can't find the gremlin I'm going to start researching that 318/360 swap. I can get ahold of several late 70s small block Mopars and transmissions pretty cheap here locally.

 

I would be more tempted to swap the wiring harness. I think it would be easier.

 

Would that be the complete harness or do they make a firewall forward harness?

 

Should be able to get an underhood harness at the junkyard.

I believe all the sensors share a single 5 volt reference..most 12 to 5 volt regulators can take a 1/2 amp load comfortably, and the voltage divider networks of the sensors take literally a couple milliamps each, except the crank and cam sensors which probably take a hundo or so.

There was a fix posted that you could bypass the internal 5V regulator by splicing in a 7805 regulator to a sensor wire and backfeed the circuit that way. If it resolved the no-bus, you found the issue.

I concur on the getting hot thing.

I doubt they have such thing as a "test PCM" for these trucks, but i would like to be wrong. The fact that the dealer supports a 15+ year old truck is a miracle in itself.