Long time reader, first time poster.  At my witts end.  Bear with me while I bring you up to speed. I have a 1998.5 2500 automatic 2wd with roughly 155K miles.  It was my grandfather's truck that I ended up with after his passing.  It wasn't in good running condition, but after some TLC it was a dream.  Work done includes - new turbo, ball joints, batteries, a/c, trailer wiring, tires, control arms, axle seals, belt, new suspension, cab lights, neutral safety switch, abs speed sensor, output speed sensor, and APPS.

Two years ago it went down on me one night while driving down the interstate, and I'm still trying to fix it.  I was on cruise and suddenly lost power, not died but lost 95% of it's output. The truck still cranks and runs fine but will only idle or jump to 1400-1500 rpm. There is no in-between or past. In gear it will barely roll in my flat driveway.  The truck has been with 3 mechanics without success and now it's back to me. 

I found continuity between my positive and negative battery cables. I tracked to C1 of the PCM and verified I had continuity to ground from pins 4 and 22.  I was also lacking ground continuity on C3 pin 28. I sent both the PCM and ECM to auto computer specialists and received them back this week.  I reinstalled and all of those continuity issues have been resolved.  

After installing the ECM and PCM my multimeter was still hooked up to my positive and negative battery terminals.  I opened the drivers door and heard the continuity tone.  I have since determined I have short to ground when either door is open or if the ignition is in run or the back position.  I have yet to understand the relation of the door jam switches and the ignition switch.  Confirmed it goes through the IOD fuse.  Attempting to track the short I came to this connector near the steering column.  I have been using the 1999 wiring diagrams for a while, but I am not able to find this connector with correct pin numbers. The pins circled have continuity to ground, but I'm not clear on their path from here. 

Apologies for such a long post. Any guidance on where to go from here is appreciated.

@Mopar1973Man , maybe you can assist here. Please review this thread and give us your thoughts. Symptoms are: engine idles fine, or jumps to 1,400 rpm when the throttle is slowly pressed. Engine rpm doesn't change while depressing throttle further. Engine has the following DTC's:

P 1693 is a companion code - no concern.

P0122 - Accelerator Pedal Position Sensor Signal Voltage Too Low

P1689 - No Communication Between ECM & Injection Pump Module

ECM and PCM has been checked by Auto Computer Specialists. Scanner show that APPS signal is 0% at idle and ramps smoothly through the throttle application range.

@CH123 , please make any corrections if I misstated something.

• John

12 hours ago, Tractorman said:

@Mopar1973Man , maybe you can assist here. Please review this thread and give us your thoughts. Symptoms are: engine idles fine, or jumps to 1,400 rpm when the throttle is slowly pressed. Engine rpm doesn't change while depressing throttle further. Engine has the following DTC's:

P 1693 is a companion code - no concern.

P0122 - Accelerator Pedal Position Sensor Signal Voltage Too Low

P1689 - No Communication Between ECM & Injection Pump Module

ECM and PCM has been checked by Auto Computer Specialists. Scanner show that APPS signal is 0% at idle and ramps smoothly through the throttle application range.

@CH123 , please make any corrections if I misstated something.

• John

Thanks John. All is correct and I will add two things to your summary-

1. The truck is slowly becoming more difficult crank. Once it fires though, it idles fine.

2. Even at 1400 rpm the truck will barely move. Power is not transferring through the drivetrain.

@Mopar1973Man - I can forward you the video I sent John.

His video has the classic touch the throttle jumps to high idle with zero control. Typically a bad PSG being the data is not reaching the PSG correctly and is being dropped. This is confirmed with the P1689 code. Throttle info not being listen too since it started and runs this shows the power is available but no data from the ECM.

Edited Monday at 06:34 PM1 day by Mopar1973Man

Here is the video @CH123 posted to my PM box.

https://photos.app.goo.gl/qGaBgUBK9mxsUXo5A