2010 Cadillac CTS Sedan AWD V6-3.6L Page 1862
4. Install the fuse that supplies B+ to terminal 56 X2 of the ECM.
Note: The 5 V reference circuit voltage can be within the specified range with a high resistance in the circuit. If this condition is suspected,
refer to Diagnostic Aids.
5. Ignition ON, test for 4.8-5.2 V between the appropriate 5 V reference circuit listed below and ground.
* APP sensor 1 terminal F or 2
* APP sensor 2 terminal C or 1
瀚慖f less than the specified range, test the 5 V reference circuit for a short to ground or open/high resistance. If the circuit/connections test
normal, replace the engine control module.
瀚慖f greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit/connections test normal, replace the
engine control module.
6. Observe the scan tool APP sensor 1 voltage parameter. Verify the voltage is less than 0.3 V.
瀚慖f greater than the specified range, test the signal circuit terminal E or 3 for a short to voltage. If the circuit/connections test normal,
replace the engine control module.
7. Observe the scan tool APP sensor 2 voltage parameter. Verify the voltage is less than 0.3 V.
瀚慖f greater than the specified range, test the signal circuit terminal B or 6 for a short to voltage. If the circuit/connections test normal,
replace the engine control module.
8. Connect a 3 A fused jumper wire between the APP sensor 1 signal circuit terminal E or 3 and the 5 V reference circuit terminal F or 2. Verify
the APP sensor 1 voltage parameter is greater than 4.8 V.
瀚慖f less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit/connections test
normal, replace the engine control module.
9. Connect a 3 A fused jumper wire between the APP sensor 2 signal circuit terminal B or 6 and the 5 V reference circuit terminal F or 2. Verify
the APP sensor 2 voltage parameter is greater than 4.8 V.
瀚慖f less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit/connections test
normal, replace the engine control module.
10. If all circuits/connections test normal, test or replace the Accelerator Pedal Assembly.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Accelerator Pedal Position Sensor Replacement (See: Powertrain Management/Computers and Control Systems/Accelerator Pedal Position
Sensor/Service and Repair)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for engine control module replacement, setup, and
programming
P2128
DTC P2122, P2123, P2127, P2128, or P2138 (Without LF1)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P2122
- Accelerator Pedal Position (APP) Sensor 1 Circuit Low Voltage
DTC P2123
- Accelerator Pedal Position (APP) Sensor 1 Circuit High Voltage
