Md1991

I have an abundance of electrical problems with my dodge cummins 3500 1999. The abs light and park brake light are on i have no speedometer or odometer and the starter clicks first time I try to start it then it'll go, and my volts when it does start are always low and it says check gauges after a couple minutes it'll go to normal. truck has a power surge at an idle. I have replaced both batteries replaced all the terminals(they were corroded really bad) had the alternator tested its good I replaced the rear abs speed sensor on rear differential I followed the wires from that sensor all the way up they're good I have takin apart every electrical connector that has to do with electrical and cleaned them all up and still no fix. I'm at a loss, everything mechanically on the truck is great. Just this electrical nightmare I'm dealing with. I have no idea where to go from here. The only thing I haven't replaced is the starter.. I noticed that the main positive power goes to the starter and no where else do you think if the contacts on the starter were gone it could cause all this??

KATOOM

It sounds like you're looking at the appropriate locations but its important to understand that the ISB is completely electronically controlled and therefor is very sensitive to any electronic parameters out of factory spec. So that means that the batteries MUST be in perfect condition with no dead cells (new doesnt mean good either) and the alternator must be charging correctly without creating excessive AC voltage noise.

Other than that, its very important to make sure ALL major connections AND grounds are clean and free from corrosion and tight. I've heard of people chasing issues which turned out to be bad grounds or faulty alternator or bad battery.

All that said, have you checked for codes?

Md1991

The only code that comes up is p0121 low voltage to the apps. Which is strange because I just replaced the apps. And yes I bought brand new batteries replaced all the terminals I've gone over every electrical cable and all grounds taken them off and cleaned them all.

KATOOM

Sounds like you have an electric gremlin or possibly overlooked something..... Moparman has a lot of good writeups about codes. I'd start looking into why you're getting the P0121 and see if it leads to a more likely reason. Mopar1973Man's Dodge Cummins Articles - P0121 APPS Sensor Volts Do Not Agree Idle Validation Signal

Busboy

I would look for a rubbed through wire intermittently shorting out on the 5 volt sensing circuits especially down by the AC compressor this could be the cause of a fluctuating voltage. Also have a look at the fuse on the very front of the PDC, it's where the +12v cable comes over from the pax side battery. The contacts on the starter solenoid are only used to supply power to turn the starter motor.