Engine/Transmission (1998.5 - 2002) 911 Thread Link

[R-N-R]

911 ECM Thread Link - Updated!

Ever experienced an ECM going nuts?



Well the problem is definately improved!!



Disconnected trans controller, re-checked both grounds to the block (2) and firewall (2), and ground to the frame. Swapped ECM with a loaner unit and the engine idled normal Oo.



PCM

P0622, Gen Field Not Switching as Expected - still present

P0122, APPS voltage Low - used to olnly show up in the ECM codes

P1765, Trans 12V different than expected - still present



ECM

P0522, Oil Pressure Voltage Low

P0122, APPS voltage Low - still present/moved from ECM to PCM



I did not reset the APPS after the batt disconnect, hopefully that explains those codes. I also did not any throttle response. The WIF light and temp swings both dissappeared. No Surging or Sputtering!!



What to do next???

 

[R-N-R]

ttt - Good news?

 

[rkressg]

A couple of things. I had a problem similar to this with a Cadillac that would not pass SW PA Emissions. The car would not pass all the readiness tests and was producing codes related to voltage. It ended up being a bad alternator. The alt would test good, but was intermittently putting out noisy power, just enough to cause a problem. A new alt fixed that problem



I recently had the p0122 code. I was able to fix it by disassembling the APPS, cleaning, and recalibrating.



I also had the p0522. It turned out being a bad Oil Pressure sending unit. The gauge on the dash showed pressure (lower than normal though). I replaced the sending unit ($60-80 from Cummins), the gauge began working correctly and the code has not come back.



Hope this helps.

-Rich