Hi Rob, I have a published bulletin that will help you with this problem. We run into this problem all the time at work. If you are happy with this responce please leave positive feed back. Thanks. Scott
#07-06-04-003: LSJ, L61, LK5, L52, LL8 Engine - Reduced Engine Power, MIL/SES Light, DTC P1516, P2135, P2138 (Replace PCM) - (Jan 19, 2007)
Some customers may comment on engine operation in the Reduce Engine Power mode with the MIL/SES light illuminated. This condition may be repeated and upon investigation, the technician may find the following DTCs set as current or in history:
This condition of a repeat DTC P1516, P2135 and/or P2138 may be caused by an internal concern with the PCM.
Important: DO NOT replace the APP sensor. Inspect the PCM build date first.
Before following the diagnostic information in SI on DTCs P1516, P2135 and/or P2138, an inspection of the PCM serial number year and Julian (PCM build) date will be necessary to determine if the PCM will need to be replaced to correct the repeat DTC P1516. Refer to Engine Control Module Replacement in SI in order to remove the PCM. Refer to the above graphic illustration (1) for the location of the PCM serial number.
The serial number is XXXXX left to right. The last digit of the year is the 9th character and the Julian date is comprised of the 10th, 11th and 12th characters and is used to determine the PCM build date. Refer to the example below to read a build date from the PCM serial number:
* 8 6 Y N AU K 1 5 3 2 5 0 R P N *
If the PCM year and Julian dates are between 5182 and 5304 , replace the PCM. Refer to the Part Catalog to order the correct PCM for your vehicle application, if necessary.
Vehicles with PCM built outside the dates should refer to SI diagnostics for DTCs P1516, P2135 and/or P2138.