No Bus, No Start, New ECU
 

Hey guys I'm in need of some help

2004 Dodge Dakota Sport Crew Cab 3.7l

About a year ago I was getting a no bus message and no start. Replaced the ECU and it's worked great until now. It seems it would randomly not start with no bus error and then after 15 minutes or so it would be fine. Then it wouldn't start for a couple of days and would eventually start and run fine for a couple days. Now it's not starting at all. I just put in a replacement ecu again for the second time and that didn't solve it.

I could some detailed troubleshooting help. Thanks :)

Something is roaching your PCM its not the PCM check for pinched wires.

If the PCM goes bad always find out what killed it first this may not be easy but needed.

PCM = power control module thats what Dodge calls them.

Check the cam and crank sensors. They use the same 5v supply and can cause a no-bus issue.

I unplugged the cam sensor and crank sensor individually and in both cases the problem remained.

So after doing all that I unplugged and plugged back in the cluster and was able to get it running again. Not sure if that's a coincidence because I had already done that previously and it didn't help.

Would the truck normally start with no cluster? Are there known issues with that connector? Or known issues with the cluster that can be fixed? Anyone know what pins are required for start on that connector? I can double check them or hard wire them.

The cluster is a computer itself. It, along with the PCM and other modules are all on the same data (PCI) bus. It could be shorting it out.

When the truck wasn't starting the cluster seemed to run the self check ok (holding trip reset and turning key on). Would that indicate the cluster itself isn't the issue?

It should be. ANY of the modules can short out the bus and lead to a "no bus" message.

Well evidently my problem isn't solved. My truck worked fine for 3 days and now it's stuck at my work. Same issue returned again. It's incredibly hard to track down when the problem seems "random". Then all the sudden it's fine for days.

Is there no step by step sure fire way to narrow this down?


Thanks again for the help.