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P2123







P2123-ACCELERATOR PEDAL POSITION SENSOR 1 CIRCUIT HIGH





For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the ignition on.

- Set Condition:
The APP Sensor #1 signal circuit is above 4.8 volts for 0.32 seconds.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

Diagnostic Test

1. DTC IS ACTIVE

NOTE: If any Sensor reference or supply voltage DTCs are present, perform the applicable diagnostic procedure before continuing with this test.

NOTE: The APP Sensor is a device that contains 2 separate potentiometer type sensors. Each sensor has its own 5-volt supply circuit, sensor ground circuit and signal circuit. The APP Sensor no longer incorporates a low-idle switch.

NOTE: The APP Sensor 2 signal should always be approximately 1/2 the voltage of the APP Sensor 1 signal.

Ignition on, engine not running.
With the scan tool, Clear DTCs in the Engine Control Module (ECM).
Fully depress and release the Accelerator Pedal several times.
With the scan tool, select View DTCs.
Is the status Active for this DTC?

Yes

- Go To 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Intermittent Condition

2. ACCELERATOR PEDAL POSITION SENSOR CIRCUIT SHORTED TO VOLTAGE




Turn the ignition off.
Disconnect the Accelerator Pedal Position Sensor harness connector.
Disconnect the Engine Control Module (ECM) harness connector.
Remove the ASD Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay Connector.
Turn the ignition on.
Measure the voltage of the (F855) Accelerator Pedal Position Sensor No. 1 5 Volt Supply circuit in the Accelerator Pedal Position Sensor harness connector.
Measure the voltage of the (K23) Accelerator Pedal Position Sensor No. 1 Signal circuit in the Accelerator Pedal Position Sensor harness connector.
Measure the voltage of the (K167) Accelerator Pedal Position Sensor No. 1 Sensor Ground circuit in the Accelerator Pedal Position Sensor harness connector.
Is there voltage present on any of the circuits?

Yes

- Repair the circuit for a short to voltage.
- Perform the ECM Verification Test Ver. 1. Verification Tests

No

- Go to 3

3. (K23) ACCELERATOR PEDAL POSITION SENSOR NO. 1 SIGNAL CIRCUIT SHORTED TO THE 5 VOLT SUPPLY CIRCUIT




Turn the ignition off.
Remove the jumper wire and install the ASD relay.
Disconnect the Engine Control Module (ECM) harness connector.
Measure the resistance between the (K23) Accelerator Pedal Position Sensor No. 1 Signal circuit and the (F855) Accelerator Pedal Position Sensor No. 1 5 Volt Supply circuit in the Accelerator Pedal Position Sensor harness connector.
Measure the resistance between the (K23) Accelerator Pedal Position Sensor No. 1 Signal circuit and the (F856) Accelerator Pedal Position Sensor No. 2 5 Volt Supply circuit in the Accelerator Pedal Position Sensor harness connector.
Is the resistance above 10.0 ohms for both of the circuits?

Yes

- Go to 4

No

- Repair the shorted (K23) Accelerator Pedal Position Sensor No. 1 Signal circuit.
- Perform the ECM Verification Test Ver. 1. Verification Tests

4. ACCELERATOR PEDAL POSITION SENSOR CIRCUIT OPEN OR HIGH RESISTANCE




Measure the resistance of the (F855) Accelerator Pedal Position Sensor No. 1 5 Volt Supply circuit between the Accelerator Pedal Position Sensor harness connector and the Engine Control Module (ECM) harness connector.
Measure the resistance of the (K23) Accelerator Pedal Position Sensor No. 1 Signal circuit between the Accelerator Pedal Position Sensor harness connector and the Engine Control Module (ECM) harness connector.
Measure the resistance of the (K167) Accelerator Pedal Position Sensor No. 1 Sensor Ground circuit between the Accelerator Pedal Position Sensor harness connector and the Engine Control Module (ECM) harness connector.
Is the resistance below 10.0 ohms for each of the circuits?

Yes

- Go to 5

No

- Repair the circuit for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 1. Verification Tests

5. ACCELERATOR PEDAL POSITION SENSOR




Remove the jumper wire and install the ASD Relay.
Connect the Engine Control Module (ECM) harness connector.
Connect a jumper wire between the (K167) Accelerator Pedal Position Sensor No. 1 Sensor Ground circuit and the (K23) Accelerator Pedal Position Sensor No. 1 Signal circuit in the Accelerator Pedal Position Sensor harness connector.
Turn the ignition on.
With the scan tool, Clear DTCs.
Fully depress and release the Accelerator Pedal several times.
With the scan tool, select View DTCs.

NOTE: The scan tool should display a Accelerator Pedal Position Sensor No. 1 low voltage or short to ground DTC with the jumper wire in place.

Does the scan tool display the DTC as described above?

Yes

- Replace the Accelerator Pedal Position Sensor.
- Perform the ECM Verification Test Ver. 1. Verification Tests

No

- Go to 6

6. ENGINE CONTROL MODULE (ECM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors the Accelerator Pedal Position Sensor and the Engine Control Module (ECM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the ECM Verification Test Ver. 1. Verification Tests

No

- Replace the Engine Control Module (ECM).
- Perform the ECM Verification Test Ver. 1. Verification Tests
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