45RFE / 545RFE Transmission

P0123- TPS/APP CIRCUIT HIGH

For the Transmission circuit diagram, refer to Wiring Diagram Information.
^ 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
- POWERTRAIN CONTROL MODULE

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Verification Tests

Theory of Operation
Due to the integration of the Powertrain and Transmission Control Modules the New Generation Control Module III will be referred as the Powertrain Control Module (PCM). The 4.7L V-8 Throttle Positioning Sensor (TPS)provides the PCM with an input signal voltage that represents the throttle blade position of the throttle body. The TPS is connected to the throttle blade shaft. As the position of the throttle blade changes, the output voltage of the TPS changes.

The 5.7L V-8 Accelerator Pedal Position Sensor (APPS) is a linear potentiometer that provides the PCM 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 PCM to calculate the throttle plate position which is electronically controlled.

Diagnostic Test
1. DETERMINING IF RELATED ENGINE TPS/APPS DTC'S ARE PRESENT
With the scan tool, check Engine DTC's, this includes all one trip failures.
Are there any Engine TPS/APPS DTCs present?
Yes >>Refer to the Driveability category and perform the appropriate symptom.
No >>Go To 2

2. CHECK IF THE DTC IS CURRENT
With the scan tool, record the EATX DTC EVENT DATA to help identify the conditions in which the DTC was set.
With the scan tool, erase Transmission DTCs.

NOTE: To erase EATX DTC EVENT DATA information, a BATTERY DISCONNECT must be performed. Performing a BATTERY DISCONNECT may reset all learned Transmission values to controller defaults that could lead to an inconsistent shift schedule.

Drive the vehicle and try to duplicate the conditions in which the DTC was reported by the EATX DTC EVENT DATA.
With the scan tool, read Transmission DTCs.
Did the DTC P0123 TPS/APPS HIGH, reset?
Yes >>Using the schematics as a guide, check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the PCM per the Service Information. With the scan tool, perform QUICK LEARN.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
No >>Go To 3

3. 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 EATX 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. Verification Tests

No >>Test Complete.