P2123
P2123-ACCELERATOR PEDAL POSITION SENSOR 1 CIRCUIT HIGH
For a complete wiring diagram refer to: Electrical Diagrams
When Monitored
With the ignition on and no other APPS No. 1 DTCs present.
Set Condition
When APP Sensor No.1 voltage is too high. Engine will additionally idle if the brake pedal is pressed or has failed. Acceleration rate and Engine output are limited. One trip fault and the code will set within 5 seconds. ETC light is flashing.
Possible Causes
- (K23) APP SENSOR NO. 1 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
- (K23) APP SENSOR NO.1 SIGNAL SHORTED TO THE (F855) 5-VOLT SUPPLY CIRCUIT
- (K23) APP SENSOR NO.1 SIGNAL SHORTED TO THE (F856) 5-VOLT SUPPLY CIRCUIT
- (K167) APP SENSOR NO.1 RETURN CIRCUIT OPEN
- APP SENSOR
- PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. APPS NO.1 VOLTAGE ABOVE 4.8 VOLTS
Ignition on, engine not running.
With a scan tool, read the APP Sensor No.1 voltage.
Is the voltage above 4.8 volts?
Yes >> Go To 2
No >> Go To 8
2. ACCELERATOR PEDAL POSITION SENSOR
Turn the ignition off.
Disconnect the APP Sensor harness connector.
Using a jumper wire, connect it from the (K23) APP Sensor Signal circuit and the Sensor ground circuit.
Turn the ignition on.
With a scan tool, monitor the Accelerator Pedal Position Sensor voltage.
Is the voltage reading 0 volt?
Yes >> Replace the APP Sensor Assembly per Service Information. After installation is complete, use a scan tool and select the ETC RELEARN function to relearn the APPS values.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 3
3. (K23) APP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
Disconnect the PCM harness connector.
Ignition on, engine not running.
Measure the voltage on the (K23) APP Sensor No.1 Signal circuit in the APP Sensor harness connector.
Is the voltage above 5.2 volts?
Yes >> Repair the short to battery voltage in the (K23) APP Sensor No.1 Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 4
4. (K23) APPS NO.1 SIGNAL CIRCUIT SHORTED TO THE (F855) 5-VOLT SUPPLY CIRCUIT
Turn the ignition off.
Measure the resistance between the (K23) APP Sensor No.1 Signal circuit and the (F855) 5-volt Supply circuit in the APP Sensor harness connector.
Is the resistance below 100 ohms?
Yes >> Repair the short between the (K23) APP Sensor No.1 Signal circuit and the (F855) 5-volt Supply circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 5
5. (K23) APPS NO.1 SIGNAL CIRCUIT SHORTED TO THE (F856) 5-VOLT SUPPLY CIRCUIT
Measure the resistance between the (K23) APP Sensor No.1 Signal circuit and the (F856) 5-volt Supply circuit in the APP Sensor harness connector.
Is the resistance below 100 ohms?
Yes >> Repair the short between the (K23) APP Sensor No.1 Signal circuit and the (F856) 5-volt Supply circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 6
6. (K167) APP SENSOR NO.1 RETURN CIRCUIT OPEN
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Measure the resistance of the (K167) APP Sensor No.1 Return circuit from the APP Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes >> Go To 7
No >> Repair the open in the (K167) APP Sensor No.1 Return circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
7. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes >> Repair as necessary
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Replace and program the Powertrain Control Module per Service Information.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
8. APP SENSOR NO.1 SWEEP
Ignition on, engine not running.
With a scan tool, monitor the Accelerator Pedal Position Sensor voltage.
Slowly press the Accelerator Pedal down.
Does voltage start at approximately 0.45 of a volt and go above 4.6 volts with a smooth transition?
Yes >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Replace the APP Sensor Assembly per Service Information. After installation is complete, use a scan tool and select the ETC RELEARN function to relearn the APPS values.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test