P0123-TPS/APP CIRCUIT HIGH
For a complete wiring diagram Refer to Section 8W.
Theory of Operation
The Accelerator Pedal Position Sensor (APPS) is a linear potentiometer. It provides the ECM and the TCM with a voltage signal proportional to the angle, or position of the accelerator pedal. The APPS signal along with inputs from other sensors is used by the ECM and the TCM to calculate the throttle position.
- When Monitored:
Continuously with the ignition on and engine running.
- Set Condition:
This DTC will set if the monitored TPS voltage rises above 4.94 volts for the period of 0.48 seconds.
| Possible Causes |
| RELATED ENGINE TPS/APPS DTC'S PRESENT |
| (K23) APP SENSOR 1 SIGNAL CIRCUIT SHORT VOLTAGE |
| (K167) APP SENSOR 1 GROUND CIRCUIT OPEN |
| ACCELERATOR PEDAL POSITION SENSOR |
| TRANSMISSION CONTROL MODULE |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
Diagnostic Test
1. CHECK IF RELATED ENGINE TPS/APPS DTC'S ARE PRESENTWith the scan tool, check Engine DTC's.
Are there any Engine TPS/APPS DTCs present?
Yes
- Refer to the Drivability Category and perform the appropriate Symptom.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Go To 2
2. CHECK TO SEE IF THE DTC IS CURRENT
With the scan tool in Transmission Sensors, read the TPS/APPS voltage.
Is the TPS/APPS voltage above 4.94 volts?
Yes
- Go To3
No
- Go To5
3. ACCELERATOR PEDAL POSITION SENSOR
Turn the ignition off to the lock position.
Disconnect the APP Sensor harness connector.
Ignition on, engine not running.
With the scan tool in Transmission Sensors, read the TPS/APPS voltage.
Is the TPS/APPS voltage below 0.5 volts?
Yes
- Go To 4
No
- Repair the (K23) APP Sensor 1 Signal circuit for a short to voltage.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
4. (K167) APP SENSOR 1 GROUND CIRCUIT OPEN
Measure the resistance of the (K167) APP Sensor 1 Ground circuit between the APP Sensor harness connector and the TCM harness connector.
Is the resistance above 5.0 ohms?
Yes
- Repair the (K167) APP Sensor 1 Ground circuit for an open.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Using the schematics as a guide, check the Engine Control Module (ECM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the ECM per the Service Information. With the scan tool, perform QUICK LEARN.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
5. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set the DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
Wiggle the wiring and connectors while checking for shorted and open circuits.
With the scan tool, check the DTC EVENT DATA to help identify the conditions in which the DTC was set.
Were there any problems found?
Yes
- Repair as necessary.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Test Complete.