Captiva

DTC P2122, P2123, 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.

Both the APP sensors 1 and 2 signal percentages increase as the pedal is depressed, from approximately 0 percent at rest to above 95 percent when fully depressed.

P2122, P2123, P2127, or P2128

P2138

P2122

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

P2123

The ECM detects that the APP sensor 1 voltage is greater than 4.7 V for less than 1 s.

P2127

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

P2128

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

P2138

The ECM detects that APP sensor 1 and APP sensor 2 disagree greater than 10 percent for less than 1 s.

OR

The ECM detects that both APP sensor 1 and APP sensor 2 are 5 percent greater than the learned minimum position for less than 1 s.

DTCs P2122, P2123, P2127, P2128, and P2138 are type A DTCs.

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 DTCs P0697 or P06A3 are not set.

⇒	If a DTC is set, refer to DTC P0641, P0651, P0697, or P06A3 for further diagnosis.

2. Ignition ON, observe the scan tool Accelerator Pedal Position percentage parameter. The scan tool should display 0 percent.
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. Observe the DTC information with a scan tool. DTCs P2122, P2123, P2127, P2128, or P2138 should not set.
5. 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 B107 accelerator pedal assembly.
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 C

•	Low reference circuit terminal D

⇒	If greater than the specified range, test the appropriate low reference circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the K20 ECM.

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

•	5 V reference circuit terminal A

•	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 K20 ECM.

⇒	If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

4. Verify the appropriate APP sensor voltage parameter is at 0 V.

⇒	If greater than the specified range, test the appropriate signal circuit terminal listed below for a short to voltage. If the circuit tests normal, replace the K20 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 A. 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 K20 ECM.

6. If all circuits test normal, replace the B107 accelerator pedal assembly.

Perform the Diagnostic Repair Verification after completing the repair.