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P2123






P2123-ACCELERATOR PEDAL POSITION SENSOR 1 CIRCUIT HIGH

For a complete wiring diagram, refer to the Wiring Information.





Theory of Operation

The Electronic Throttle Control (ETC) system uses two Accelerator Pedal Position (APP) Sensors to monitor the accelerator pedal position. The APP Sensors 1 and 2 are integrated into one assembly located at the pedal assembly. Each sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The Powertrain Control Module (PCM) reads the two signals individually and then compares the two signals as a redundant check of the throttle position. One of the sensors will fluctuate between 0 volts and 5.0 volts and the other sensor will fluctuate between 0 volts and 2.5 volts. The fluctuation of the two sensors should move proportionately. E.G. When operating properly, the voltage reading of the sensor operating on the 5.0 volt scale will always approximately two time the voltage reading of the sensor on the 2.5 volts scale.

- When Monitored:
With the ignition on and battery voltage greater than 10.4 volts.

- Set Condition:
The Powertrain Control Module (PCM) detects that the APP Sensor 1 input voltage is above the maximum acceptable value. One trip fault. If the vehicle is equipped with the stop/start feature, the system will be disabled when this DTC is active.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

Diagnostic Test

1. DTC IS ACTIVE

NOTE: Diagnose and repair any system voltage or sensor reference voltage DTCs before continuing with this test.

1. Start the engine and allow it to reach normal operating temperature.

WARNING:
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

2. With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. (K852) 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE




1. Turn the ignition off.
2. Disconnect the Accelerator Pedal Position Sensor harness connector.
3. Disconnect the Powertrain Control Module (PCM) C1 harness connector.
4. Turn the ignition on.
5. Measure the voltage of the (K852) 5-Volt Supply circuit in the Accelerator Pedal Position Sensor harness connector.

Is there any voltage present?

Yes

- Repair the (K852) 5-Volt Supply circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. (K23) APP SIGNAL 1 CIRCUIT SHORTED TO VOLTAGE




1. Measure the voltage of the (K23) APP Signal 1 circuit in the Accelerator Pedal Position Sensor harness connector.

Is there any voltage present?

Yes

- Repair the (K23) APP Signal 1 circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. (K23) APP SIGNAL 1 CIRCUIT SHORTED TO THE (K852) 5-VOLT SUPPLY CIRCUIT




1. Measure the resistance between the (K23) APP Signal 1 circuit and the (K852) 5-Volt Supply circuit in the Accelerator Pedal Position Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the (K23) APP Signal 1 circuit for a short to the (K852) 5-Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 5

5. (K23) APP SIGNAL 1 CIRCUIT SHORTED TO THE (K854) 5-VOLT SUPPLY CIRCUIT




1. Measure the resistance between the (K23) APP Signal 1 circuit and the (K854) 5-Volt Supply circuit in the Accelerator Pedal Position Sensor harness connector.

Is the resistance below 1000 Ohms?

Yes

- Repair the (K23) APP Signal 1 circuit for a short to the (K854) 5-Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 6

6. (K23) APP SIGNAL 1 CIRCUIT OPEN OR HIGH RESISTANCE




1. Turn the ignition off.
2. Measure the resistance of the (K23) APP Signal 1 circuit between the Accelerator Pedal Position Sensor harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 7

No

- Repair the (K23) APP Signal 1 circuit for an open circuit or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

7. (K167) SENSOR GROUND CIRCUIT OPEN OR HIGH RESISTANCE




1. Measure the resistance of the (K167) Sensor Ground circuit between the Accelerator Pedal Position Sensor harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 8

No

- Repair the (K167) Sensor Ground circuit for an open circuit or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

8. ACCELERATOR PEDAL POSITION SENSOR
1. Turn the ignition off.
2. Connect the PCM C1 harness connector.
3. Connect a jumper wire between the (K167) Sensor Ground circuit and the (K23) APP Signal 1 circuit in the Accelerator Pedal Position Sensor harness connector.
4. Turn the ignition on.
5. With the scan tool, read the Accelerator Pedal Position Sensor signal voltage.

Is the voltage below 1.0 volt with the jumper wire in place?

Yes

- Replace the Accelerator Pedal Position Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 9

9. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Accelerator Pedal Position Sensor and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
5. Look for the data to change or for the DTC to reset during the wiggle test.
6. Perform any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module (PCM).
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

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