I have been trying to diagnose a check engine light. It would start really hard when cold (0 F and colder) Changed air bypass valve. Also changed fuel filter. Now truck runs great but still have error codes, but is sucking gas down like it thinks it is a 460cid.
Read codes. Changed both downstream O2 sensors. No change in codes. Borrowed a friends computer scanner/tester. I can see O2 sensor on bank 2 sensor 2 has 8 milliamps once warmed up. At first it was 4. But I pulled PCM to get part # and put it back in and now it is 8. I put a second new 02 sensor in bank 2 sensor 2 and still no change. Looked over wires, can't find chaffing. I don't do off road and do mostly highway or intown driving and truck hasn't been abused.
With P1000 code it is telling me the OBC isn't going all the way through not sure if that is a default once an error is reached in the initial checking and stops further stuff in a default mode.
Having eliminated the actual O2 sensors and did a fair job checking the wires, is it safe to say the PCM is bad and I need to get a new one? Or should I tear into the wiring harnesses looking for a short or break?
I have a new (read used from junk yard) pcm sitting there to go to dealer to get programed. Just looking for other avenues to troubleshoot before the dealership rapes me with their obsurd hourly charges.
Thanks.
Read codes. Changed both downstream O2 sensors. No change in codes. Borrowed a friends computer scanner/tester. I can see O2 sensor on bank 2 sensor 2 has 8 milliamps once warmed up. At first it was 4. But I pulled PCM to get part # and put it back in and now it is 8. I put a second new 02 sensor in bank 2 sensor 2 and still no change. Looked over wires, can't find chaffing. I don't do off road and do mostly highway or intown driving and truck hasn't been abused.
With P1000 code it is telling me the OBC isn't going all the way through not sure if that is a default once an error is reached in the initial checking and stops further stuff in a default mode.
Having eliminated the actual O2 sensors and did a fair job checking the wires, is it safe to say the PCM is bad and I need to get a new one? Or should I tear into the wiring harnesses looking for a short or break?
I have a new (read used from junk yard) pcm sitting there to go to dealer to get programed. Just looking for other avenues to troubleshoot before the dealership rapes me with their obsurd hourly charges.
Thanks.
Feb 16, 2009 at 9:08 AM

