After a $600 repair of my sisters 97 3.9 Dak Auto a new problem starts.
The computer was replaced for a no spark problem along with cps and tps.
The new problem.....the gages work sometimes..fuel will work no tach then all will work then air bag light comes on all quit odometer goes on and off then air bag goes off tach fuel alt temp work no spedo. This happens in a matter of minutes.Pulled codes missfire on cyl 4 5 2. I think it might be a bad computer......any ideas
Thanks

 

This may seem like a stupid question, but it's valid. Was the PCM replaced with the correct part number? Was it programed to the correct VIN? Was it a used PCM or new? Installed at a local shop or dealer or yourself? I believe your gauge problems may be related to an incorrect PCM programming, or indeed another bad PCM.
Also, was the CPS properly learned by the PCM? That could cause the mis-fire codes. If it's really mis-firing on 3 of 6 cylinders then it should run like crap, if at all.

 

It was replaced by a local mechanic we trust.It was a rebuilt and reprogramed with the vin I think.Not shure where he bought it.The truck runs fine no miss that I can feel.

 

check the alt output. when they start to die, they can do wacky things to anything computer controlled.

 

check your ground?