Series 60 Detroit DDEC3

Be sure to share the findings.

 

I worked on a truck years ago with this same problem. I don't 100% recall what the fix was but I would definitely try a test ECM.

Edit: I almost remember that it was just corrupt software on the ECM?

 

We overhauled a truck once that did this. Ended up being the ECM. The truck had never been to our shop. They pulled right into the stall and shut it off and supplied all the parts (overhaul kit, injectors, bullgear, just about everything). We did an out of frame on it. Put it back together and fired it up. Ran OK sometimes. We thought it might have been out of time so we checked it. Ran the overhead several times. No engine codes. Then one day I got in it to back it out to pull something else in and when I pushed the park brake in the engine changed tunes. Pull it out ran fine. Push it in and it started running like crap. Put a test ECM on it and it ran fine from then on. This might be worth trying. If the truck is a white Classic then you might have inherited it and we never did really fix it. LOL

 

So not all Ecms have the Calibration setup the same Maybe the Spare ECM you put had a Diffrent Calibration setup there are settings in the Calibration specific to Park brake on or off which makes a Change to Certain things

 

Not sure. We just used the ECM that was on it to start. Like I said we had never laid eyes on the truck. They pulled right into the stall and shut it off and we went to work. I even spoke to Rebel about this truck several times trying to figure out what was up.

 

Here is a diagram but i doubt that you have any wire issues but we shall see thanks