This TSB applies to 2005-2011 GM passenger cars and light-duty trucks, as well as 2005-2009 Hummer H2, 2006-2010 Hummer H3 and 2005-2009 Saab 9-7X vehicles. Some customers may comment on an intermittent malfunction indicator lamp on, with a message or an indicator that displays Reduced Engine Power. The technician may observe DTC P2138 (accelerator pedal position (APP) sensor 1-2 correlation) set as current or in history.
This condition may be caused by water intrusion into the instrument panel (IP) to body harness connector, which carries the APP sensor signals to the ECM/PCM. This water intrusion results in a voltage difference between APP sensor 1 and APP sensor 2 that exceeds a predetermined value for more than a calibrated period of time, setting P2138.
NOTE: Aftermarket equipment can generate DTC P2138 and/or other DTCs.
1. Verify that aftermarket equipment is not electrically connected to any of the APP sensor signal or low reference circuits or to any other ECM/PCM 5V reference or low reference circuits.
2. Perform the diagnostic system check. If any 5V reference DTCs are set, refer to the DTC list. If any 5V reference DTCs are not set, proceed to Step 3.
3. Locate the IP to body harness connector, which may be located in and around the left hand kick panel area or inside the IP. Depending on the vehicle and model year, refer to Wiring Systems or Power and Signal Distribution in the service manual. NOTE: Some examples of potential water leaks are A-pillar seals, sunroof drain lines and windshield/cowl sealing.
4. Inspect for a water leak. If necessary, use a water hose to determine the source of the leak. If a water leak is found, repair as necessary.
5. Inspect the IP to body harness connector terminals for corrosion and debris. Repair as necessary.
6. After completing the repair, verify proper operation.
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