I'm getting the NO BUS error code after about 45 minutes or so of driving. (when the truck warms up). Truck randomly shuts off, no RPM's, no power steering, NO BUS for about 30 minutes until the truck cools off then it'll start right back up and run fine...

Anyone know why?

Replaced: (it's a 1999 Dodge Dakota 4x4 3.9L V6 with about 190k miles)

remanufactured (new with warranty) PCM from NAPA... (about 2 months old, ran perfectly in the winter). Could I have gotten a bad one? The one I replaced went bad but never got no bus with it.
Brand new Crank Sensor
New IAC
New fan clutch (was concerned about overheating)

Still getting no bus. Please any help is appreciated, thank you

 

What brand crank sensor?

Something is getting hot, and failing. Trouble is, could be almost anything under the hood.

 

It could be a bad PCM. Electronics don't like it when they get hot. But, it could also be a bad cam or crank sensor. They can fail and cause the "no bus" code too.

Only use OEM for both.

 

Crank sensor is one from advanced, had swapped an OEM one before. Lifetime warranty one from advanced auto. It's a day old now.

Just recently replaced the cam with an OEM sensor as well, how could you test the PCM to see if it's bad when its no bussing?

 

You really can't test the PCM. You basically rule out everything else.

 

I just replaced the PCM for $500 that's why I'm just confused on what to do. The last one was bad, it stopped sending transmission codes and prevented the tranny from shifting out of first gear. The one in it now is under warranty though. Was able to test the last one (power probed the signals from it), not sure how to do this one with the no bus. Any idea what else it could be other than cam, crank, or PCM?

thanks man

 

Check for 5 volts at the sensors.

 

They all seem to be working fine, when there's no no bus. The thing is trying to get the no bus to happen when we want to test everything... it shuts off when we don't want it to, and it's not shutting off when we want it to to test things... so that's why we're baffled and can't figure out what is causing the no bus.

The only sensor we haven't replaced yet now is the governor sensor on the transmission that uses a 5 volt supply.

So probably faulty PCM even though I just bought it remanned a month ago?

 

Some of the reman's are worse than the broken one you are replacing.....

Any of the sensors that take a five volt feed can cause the no bus. That includes the O2 sensors as well. Doesn't necessarily have to be a bad sensor though, might be a wiring problem TO one of the sensors.

 

O2s seem fine. Cant see any issues with wires. Yeah I wish you could buy a new pcm but you simply can't only remanned. Dodge dealer said to buy from napa they dont sell them. My old one never shut the truck off but it threw random cylinder misfires, oxygen leaks and prevented the transmission from shifting... -_-