huntduck
New member
- Joined
- Mar 19, 2012
- Messages
- 514
I'm helping a buddy out with an erratic idle on a 2002 3500. I checked the fuel lift pump pressure....10psi @ idle. Drops to 7-8psi under a load. I checked the APPS using an analog voltmeter. I didn't see any weird drops or skips when moving the throttle with the key on. I did a "hot wire" test on the pump. When I did that the truck ran smooth, idled great. Cleaned up the connector for the ECM on the injection pump and the connector for the APPS. Truck went back to an erratic idle.
Now for the rest of the story, Truck went to a trans shop for a rebuild. Buddy was complaining about a surge when in overdrive. He said the shop put a wire from the APPS connector to the PCM to ground. The wire they tapped into on the APPS connector is the blue with black tracer, which is the signal wire for the APPS. That's where I made my checks for the APPS. I thought maybe it was giving a poor signal causing the erratic idle. So, I clipped that wire and started truck again.....truck ran smooth. Everything connected like it should be. But, now it won't shift into overdrive. Reconnect the wire, overdrive works fine and idles crappy.
I don't have a wiring schematic and I'm not sure why the trans shop would add that wire? Looking for some help. Schematic....something. Thanks.
Now for the rest of the story, Truck went to a trans shop for a rebuild. Buddy was complaining about a surge when in overdrive. He said the shop put a wire from the APPS connector to the PCM to ground. The wire they tapped into on the APPS connector is the blue with black tracer, which is the signal wire for the APPS. That's where I made my checks for the APPS. I thought maybe it was giving a poor signal causing the erratic idle. So, I clipped that wire and started truck again.....truck ran smooth. Everything connected like it should be. But, now it won't shift into overdrive. Reconnect the wire, overdrive works fine and idles crappy.
I don't have a wiring schematic and I'm not sure why the trans shop would add that wire? Looking for some help. Schematic....something. Thanks.
