This Bulletin is being revised to add additional diagnostic service information. Please discard Corporate Bulletin Number 07-06-04-019 (Section 06 - Engine/Propulsion System)
Some customers may comment on an intermittent MIL/SES light Illuminated with a message center or an indicator that displays Reduced Engine Power. DTC P2138 - Accelerator Pedal Position (APP) Sensor 1-2 Correlation may be set. The voltage difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value for more than a brief period. Refer to DTC P2138 in SI for further diagnostics.
On some vehicles, the IP to body harness connector, which carries the APP signal to the ECM/PCM, is located in the left hand kick panel area or inside the IP. Water intrusion into these areas could cause an electrical short in the APP circuits setting a P2138 code.
Note: Make sure that no add-on/aftermarket equipment is electrically connected to the APP signals or to the other ECM/PCM five volt reference or return lines. These can generate false P2138 and/or other ETC System DTCs. If there are other engine DTCs besides P2138, such as MAP sensor faults (i.e. P0107, P0108), resolve these first before attempting to diagnose P2138 DTCs.
Important: Refer to DTC P2138 in SI to confirm that the ETC pedal is operating correctly.
Locate the IP to body harness connector, which may be located in and around the left hand kick panel area or inside the IP. Check to see if there is a water leak into the area and repair as necessary. Use a water hose to determine the source of a water leak and effectiveness of repair. Some examples of potential water leaks are: A-pillar seals, sunroof drain lines (if so equipped) and windshield/cowl sealing. Finally, repair or replace the IP to body harness connector, making sure no corrosion or debris is left on or between the terminals.
For vehicles repaired under warranty, use:
Wiring And/Or Connector-Emissions System - Repair Or Replace
Use Published Labor Operation Time
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
This PI was superseded to update models and engines. Please discard PIP3783A.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
The customer concern may be a SES light on with a reduced power message.
Complete the current SI diagnostics for any symptoms or DTCs found. If the vehicle was brought in for a reduced power message and DTCs P2120, P2122, P2123, P2125, P2127, P2128, or P2138 were found, inspect connectors C109 and C205. Connector C109 is located on the left side of the engine compartment below the underhood fuse block. Connector C205 is located under the Upper Instrument Trim Panel. To access connector C205 use the SI procedures for Instrument Panel Upper Trim Panel with Windshield Defroster Nozzle Grille Replacement.
Inspect all terminal and pin fits at connectors C109 and C205. Make sure the connectors are properly seated and locked. Make necessary wiring repairs following SI procedures.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.