My son owns a 99 dakota 3.9L truck. The problem started with an occasional miss as he was driving. Its turned into an intermittant no bus, starts but runs rough or starts and runs great for a mile or two. Took to a mechanic who basically threw parts at it. Only code that shows up sometimes is the purge solenoid which the mechanic has replaced. He said it had to be pcm so I replaced that with no change in symptoms. Its been sitting for a month now and when you try and start it it will barely start and run rough then when you turn ignition off and restart it runs perfect sitting there. Sometimes when you go to start it you will get the flashing odometer with the no bus but it eventually goes away. Any ideas would be appreciated.

 

Welcome to the forum.

You have a 2 wire CCD bus in a '99 Dakota. The PCM, CTM, air bag computer, ABS controller, the cluster, etc, are all computers. If any one of them or the wiring between them is bad it could short out the bus.

But, I'd give the cam and crank position sensors a good look. Both of these are common failure points, they may not always cause a code, and both can short the PCM. It can also explain the rough running/hard start.

Do you have the exact code for the purge solenoid?

On the purge solenoid, and really ANY sensor you change, use only Dodge parts. There have been many on this forum that have been having problems with aftermarket parts lately.

 

I have replaced the crank position sensor. I will give the cam position sensor a look. If something was shorted would you still be able to get the 5 volts at the sensors connector? TPS and CPS for example.

 

did it work with the cam sensor? I am basically having same problem. thanks