How do I tell what module the DTC is set by?  ECM or PCM?  I have a 99 so the key reading codes with the key on/off does not work.  I do have a code reader (BlueDriver)

A little background about 4 months ago it got pretty cold and I had a rough cold start which popped P0122 with a slight pedal stutter.  Cleared code chalked it up as a cold start low voltage issue.  A week or so later it did it again a couple of times.  I swapped out with a Timbo Apps and no more issues.  This morning another cold morning not too bad of a cold start no pedal issues detected however It popped P0122 again.  I am now wanting to go through the complete troubleshooting tree however I do not know if the code is set by the PCM or ECM.  I am also pretty sure that this just shows up sporadically when cold enough outside. 

 

*Update:  I am assuming, looking at the wiring diagram, that the ECM would have to throw this code so I will troubleshoot the ECM route first.  If I find nothing I will go the PCM route.  I think the chances of my Timbo APPS being defective are very low.

Edited May 17, 20177 yr by deehammer

Not being a smartbutt posting this. Bare with me. PCM can cause this as there is a circuit that runs to the pcm for the apps.

 

 

I would read over the link that @jlbayes posted and review you electrical for the ECM to the APPS. The signal for the PCM is between the ECM and PCM but typical its the APPS to ECM.

CEL has gone out like usual however the code was still showing up on my scan tool.  I cleared the code and it came back again but there is no CEL anymore.  Don't know if that has any merit on it at all being ECM vs PCM.  I will be running through the procedure when I get time soon and will update then. 

18 hours ago, deehammer said:

CEL has gone out like usual however the code was still showing up on my scan tool.

Error codes will not self-erase till 40 warm up cycles have been completed without any more errors recorded.