P2121 Code no throttle response

[mbpoindexter]

Hello, I am hoping someone here can brainstorm with me to get me over this hump I've been dealing with a long time now.

 

Quick background: truck is a 2005 dodge ram 3500 VIN but has 2004 motor, trans, and ECM. I unknowingly purchased it like this. The truck was cheap I knowingly bought it hoping for just mechanical problems. I overhauled the motor it had 3 broken rings, replaced all injectors, etc. etc. Unfortunately over the last 2 years I have only had intermittent time to work on the truck roughly 2 weeks every 6 months. The truck now cranks and fires great every time and idles well except for a little bit of white smoke which is expected as the truck has less than intermittent miles since overhaul and has BBI stage 0.5 injectors and no Cat. None of that is important. 

 

Now, I have been dealing with a dead pedal problem. The truck has literally 0 throttle response at the moment. I have tried resetting 2 APPS that I have 2-3 times each today, for whatever reason the computer does not like the reset and the throttle stays dead.

 

Yesterday I had 5 codes:

P2509
P2121
P2122
P2123
P2127

 

I know this P2509 is a code that will trigger other codes so I checked grounds and charged batteries which were at 12.3 and 12.4 volts before charging. At this low voltage none of the codes would clear with my scanner. I tried 3-4 times and they al instantly came back. They are now at 12.7v each and this P2509 code is now gone along with P2122 P2123 and P2127 all cleaned with code reader. I also suspected the alternator causing these low and high voltage codes so I had it benched tested 3 times which it passed 3 times. I also am not getting these codes to return even with the alternator attached. As long as the batteries have the voltage they should it seems those codes have not returned.

 

This leaves P2121 which I cannot clear with the code reader and cannot get to go away for the life of me. There is no throttle response.

 

It is also worth noting that I have replaced the wiring harness as it was broken in a different spot I thought it was causing these issues as well. I ohm checked the new one and it seems all wires are intact as they should be.

 

Any ideas? I was thinking of having the truck towed and ECM flashed just in case its something to do with a previous tuner but I doubt that. Anyone have any ideas or things I can try?

 

I have today off work so I will be trying to figure this out all day today. Thanks

[mbpoindexter]

I want to add now that I installed a new APPS sensor. After calibrating the truck started and idled and the throttle worked. I drove it around for about 30 minutes trying to get it to stop working but it never did. I knew it would come back eventually so I returned to my garage and put the range selector into park. At that moment the idle RPM went up to 1100ish RPM. I shut the truck off and restarted and boom, no throttle. Codes have not set yet but Id bet my house it will be P2121. 

 

Anyone had this problem before? Is it transmission related? everything was fine with the idle speed until i put it in park....any help.....

Edited May 25, 2021 by mbpoindexter

[mbpoindexter]

I'll add a video I took this morning. Maybe it can give someone some ideas as to whats going on.

 

In this video the throttle is dead. Regardless of whether I have the transfer case engaged or not the truck has no throttle. When I put the range selector to reverse, the alarm goes off. I took the fuse out of the horn so you cannot here it.

 

This happens only when the throttle is dead, so when I was driving it yesterday I could put it into reverse and drive no problem.

 

When I put the truck into neutral, the range selector never actually selects neutral even though we are in neutral and the alarm goes off with thee dash flashing like crazy. I'll attach the video link. ANY ideas?

 

 

[Mopar1973Man]

Few to look at...

 

Check for AC noise from the alternator.

Might consider checking all wiring between the ECM and the APPS sensor.

Check on all grounds.

If none of this works you'll need to pull the ECM and have it tested and repaired.