Captiva

DTC P2120, P2122, P2123, P2125, P2127, P2128, or P2138

The accelerator pedal assembly contains 2 accelerator pedal position (APP) sensors. The APP sensors are mounted to the accelerator pedal assembly and are not serviceable. The APP sensors provide a signal voltage that changes relative to pedal position. The engine control module (ECM) supplies each APP sensor with a 5 V reference circuit, a low reference circuit, and a signal circuit.

P2120, P2122, P2123, P2125, P2127, P2128

P2138

P2120

The ECM detects the APP sensor 1 voltage is less than 0.46 V or greater than 4.75 V for greater than 1 s.

P2122

The ECM detects the APP sensor 1 voltage is less than 0.46 V for greater than 1 s.

P2123

The ECM detects the APP sensor 1 voltage is greater than 4.75 V for greater than 1 s.

P2125

The ECM detects the APP sensor 2 voltage is less than 0.32 V, or greater than 2.6 V for greater than 1 s.

P2127

The ECM detects the APP sensor 2 voltage is less than 0.32 V for greater than 1 s.

P2128

The ECM detects the APP sensor 2 voltage is greater than 2.6 V for greater than 1 s.

P2138

The ECM detects the voltage difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value for greater than 1 s.

P2138

The voltage difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value for greater than 2 s.

DTCs P2120, P2122, P2123, P2125, P2127, P2128, and P2138 are Type A DTCs.

A high resistance condition on the APP sensor circuits could cause a DTC to set.

Ensure that the in-line harness connector seals are installed correctly. Improper installation could result in water intrusion into the connector and cause a DTC to set.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Throttle Actuator Control (TAC) System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the DTC information with a scan tool. Verify DTC P0641 or P0651 is not set.

⇒	If a DTC is set, refer to DTC P0641 or P0651 for further diagnosis.

2. Observe the scan tool APP Sensor 1 and 2 voltage parameters. Both parameters should be between 0.13-4.87 V and change with accelerator pedal input.
3. Observe the scan tool APP Sensor 1 and 2 Agree/Disagree parameter while performing the following tests:

•	Rapidly depress the accelerator pedal from the rest position to the wide open throttle position (WOT) and release pedal. Repeat the procedure several times.

•	Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times.

The APP Sensor 1 and 2 Agree/Disagree parameter should display Agree.

4. Clear the DTCs with the scan tool. Operate the vehicle within the Conditions for Running the DTC or within the conditions that you observed from the Freeze Frame/Failure Records.
5. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P2120 or P2125 are not the only accelerator pedal position DTCs set.

⇒	If DTC P2120 or P2125 are the only DTCs set, replace the ECM.

6. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, disconnect the harness connector at the accelerator pedal.
2. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 Ω between the low reference circuit terminals listed below and ground.

•	Low reference circuit terminal A

•	Low reference circuit terminal D

⇒	If greater than the specified range, disconnect the ECM and test the appropriate low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, test for 4.8-5.2 V between each 5 V reference circuit terminals listed below and ground.

•	5 V reference circuit terminal C

•	5 V reference circuit terminal F

⇒	If less than the specified range, test the appropriate 5 V reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the ECM.

⇒	If greater than the specified range, test the appropriate 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Verify the scan tool APP sensor 1 and 2 voltages are less than 0.3 V.

⇒	If greater than the specified range, disconnect the ECM and test the appropriate signal circuit terminal listed below for a short to voltage. If the circuit tests normal, replace the ECM.

•	APP sensor 1 signal circuit terminal E

•	APP sensor 2 signal circuit terminal B

5. Install a 3 A fused jumper wire between the appropriate signal circuit listed below and the 5 V reference circuit terminal C. Verify the appropriate APP sensor voltage parameter is greater than 4.8 V.

•	APP sensor 1 signal circuit terminal E

•	APP sensor 2 signal circuit terminal B

⇒	If less than the specified range, test the appropriate signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

6. If all circuits test normal, replace the accelerator pedal assembly.

Perform the Diagnostic Repair Verification after completing the repair.