I think my ECM is mixing hot wires into ground..

ECM will only affect the engine fan and engine brake, from what you've listed here.

FWIW, I had an engine fan that stayed on constantly in my 98 Pete 377 with Detroit 60. Turned out to be the wiring harness rubbing through the harness wire insulation at the back of the engine. The fuel temperature wire shorted to ground, and caused the fan to run continuously. At 1.65 mil, you could have wires in the harness that are broken inside the insulation where you can't see the problem. Also, since it's a new rebuild, perhaps some of the connectors weren't secured properly, or some of the internal pins on the connectors were pushed out when they were re-connected. Anything is possible with a truck with that high of a mileage. It's going to take time to go through everything to find the issues.

Try to tackle one issue at a time, and use a methodical approach to troubleshooting.

 

mine is showing trailer abs light(2015 dorsey) comes on the most, couple of times the low coolant light, regen and now the engine fan wont come on, had to run it in manual. 09 386 485isx

 

Are you un hooking the Jake solenoid wire from the solenoid. If not you are grounding thru the solenoid body. A digital volt ohm meter is all you really want to use around the ECM as it has 12 v supply and 5v reference voltage for all sensors. For the Jake problem look right where the harness goes thru the valve cover most of the time you will find a wire broke inside the insulation as posted earlier. Gentle is key when unplugging and replugging connectors. Look in each one and make sure everything still looks right. Also check the clutch and brake switch, Some cats are set to only jake with the brake pedal when cruise is on. I would say you have harness issues not ECM trouble.

 

It's difficult to find ghosts and it will definitely turn your hair gray. Very seldom do cat ecms fail. Usually when you finally find your problem, it's like windsmith said. Shorted wiring or open wiring, shorted sensor that's corrupting voltage etc. You need a good wiring diagram and some code diagnostic equipment to begin the adventure. Supermiller has some available Pete wiring diagrams that you can view. I don't know if they cover your particular year and model but anything close would help with the guess work.

 

I would start by doing some conduity tests. Best way to find a bad wire.

 

Do you have any codes in the engine or ABS ECM? I doubt that the ECM is mixing powers and grounds. Many inputs and outputs of the ECM switch the ground side of the circuit. When a ground opens, it will show full voltage at the ground. This is not supplied by the ECM, but from the component. If you have a simple circuit with a just a light, unhook the ground and the ground will read 12 volts because the circuit is open. The same thing happens when an ECM switches a ground to deactivate something. This is probably why you can back probe an see 12 volts at a ground pin.

 

05 Peterbilt 379 c15 acert....tach ...volt meter and fuel gauge not working. put truck in reverse and everything works . Could it be a ground issue?