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P0122 Diagnostic question

Yoshi
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Yoshi

Yoshi

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I want to start off by saying a huge thank you to @Mopar1973Man for providing this excellent resource for the ram community!

 

I had the P0122 code and the truck would just randomly turn off after a few minutes of running. Would happen whether parked, driving, on a hill, on flat gound, under acceleration, and deceleration. It didn't matter what the truck was doing, it would just turn off. It started off doing intermittently and then just got worse and worse to where it happens quite frequently. I replaced the factory APPS with a Timbo APPS and did the learn procedure. It seemed to fix the problem. But after a while the CEL would return. Then started the random dying again.

 

After it would die, I could fire it right back up with no issues, like nothing happened. Consistent fuel pressure all the time and no trouble starting.

 

So I did some research and found the diagnostics on this site for the code. During the diagnostics I found that the previous owner had spliced in a wire to the Orange/Dark Blue wire right off the PCM A23 that ran to a ground. Is there supposed to be continuity between A23 and Ground? From the diagnostics it seems like there shouldn't be. 

 

I went ahead and removed the splice and reset the ecu. When I turned it on, I did the relearn procedure for APPS and drove the truck. It seemed to work fine, no CEL and no stalling... I'm wondering if that could have been my problem?

 

Also here is the results of the diagnostics for P0122:

Testing

1. Turn ignition on with engine off. Using DRBIII(R) scan tool, check for ECM and PCM DTCs. Determine if DTC is set by ECM or PCM. If DTC is set byECM, go to next step. If DTC is not set by ECM, go to step 7.

 

At the start of the testing I had P0122 code.

 

2. Turn ignition off. Disconnect APPS sensor harness connector. APPS is located on the bracket, just above fuel injection pump. Turn ignition on with engine off. Using DVOM, measure voltage between cylinder block (ground) and terminal No. 5 (Dark Blue/White wire) on APPS harness connector. If the voltage is greater than 4.5 volts, go to next step. If the voltage is 4.5 volts or less, go to step 6

 

6 Volts

 

3. Turn ignition off. Ensure APPS harness connector is still disconnected. Check for continuity between terminal No. 4 (Black/Yellow wire) and terminal No. 5 (Dark Blue/White wire) on APPS harness connector. If continuity does not exist, go to next step. If continuity exists, repair short between Dark Blue/White and Black/Yellow wires. The Black/Yellow wire is the sensor ground circuit.

 

Went ahead and tested for these following steps to be safe. There was no continuity.

 

4. Ensure APPS harness connector is still disconnected. Disconnect ECM harness connector. ECM is located on driver's side of the engine, just in front of fuel transfer pump and contains a 50-pin connector. Check for continuity between terminal No. 4 (Black/Yellow wire) and terminal No. 3 (Light Blue/Black wire) on APPS harness connector. If continuity does not exist, go to next step. If continuity exists, repair short between Black/Yellow and Light Blue/Black wires.

 

No continuity

 

5. Ensure APPS and ECM connectors are still disconnected. Check for continuity between ground and terminal No. 5 (Dark Blue/White wire) on APPSharness connector. If continuity does not exist, go to next step. If continuity exists, repair short to ground in Dark Blue/White wire.

 

No continuity

 

6. Turn ignition off. Ensure APPS connector is still disconnected. Disconnect ECM harness connector. ECM is located on driver's side of the engine, just in front of fuel transfer pump and contains a 50-pin connector. Check Dark Blue/White wire for continuity between terminal No. 5 on APPS harness connector and terminal No. 31 on ECM harness connector. If continuity does not exist, repair open in Dark Blue/White wire. If continuity exists, replace and program the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.

 

Continuity existed...

 

7. Turn ignition off. Disconnect PCM harness connectors. PCM is located at passenger's side rear corner of engine compartment. Check for continuity between ground and terminal A23 (Orange/Dark Blue wire) on PCM harness connector (APPS circuit). If continuity does not exist, go to step 9. If continuity exists, go to next step.

 

Again, I went ahead and continued testing. No continuity.

 

8. Disconnect ECM harness connector. ECM is located on driver's side of the engine, just in front of fuel transfer pump and contains a 50-pin connector. Check for continuity between ground and terminal A23 (Orange/Dark Blue wire) on PCM harness connector (APPS circuit). If continuity does not exist, the test is complete. If continuity exists, repair short to ground in Orange/Dark Blue wire.

 

No continuity.

 

9. Ensure PCM harness connectors are still disconnected. Disconnect ECM connector. ECM is located on driver's side of the engine, just in front of fuel transfer pump and contains a 50-pin connector. Check for the circuit). If continuity does not exist, go to next step. If continuity exists, repair short to ground in Orange/Dark Blue wire.

 

I'm not really sure what this is asking.. There was no continuity between ground and PCM Orange/Dark Blue and no Continuity between ECM Orange/Dark Blue and Ground. But there was continuity between PCM Orange/Dark Blue and ECM Orange/Dark Blue.

 

10. Check Orange/Dark Blue wire for continuity between terminal No. 5 on APPS harness connector and terminal No. 31 on ECM harness connector. If continuity does not exist, repair open in Orange/Dark Blue wire. If continuity exists, go to next step.

 

I don't understand this one either... How should I test this? Should there be continuity between A23 on PCM connector and the Blue/White wire on ECM and APPS Connectors? There was not continuity between A23 on PCM and the Blue/White wires on ECM/APPS Connectors. 

 

11. Reconnect ECM harness connector. Ensure PCM harness connectors are still disconnected. Turn ignition on with engine off. Using DVOM, measure voltage between ground and terminal A23 (Orange/Dark Blue wire) on PCM harness connector (APPS circuit). If the voltage is greater than 0.4 volt, the test is complete. If the voltage is 0.4 volt or less, go to next step.

 

With the APPS plug connected, I had .688 Volts

 

12. Turn ignition off. Disconnect APPS harness connector. Check for continuity between ground and terminal A23 (Orange/Dark Blue wire) on PCMharness connector (APPS circuit). If continuity does not exist, replace APPS. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. If continuity exists, replace and program the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.

 

There was no continuity between A23 and ground... is this correct?

 

I want to hold off on buying a new ECM until I know removing that spliced in ground helped or not...

 

MoparMan, do you have any input?

 

Thanks for all your help!

 

-Josh

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