P0123-TPS/APP CIRCUIT HIGH

For a complete wiring diagram Refer to Section 8W.

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.

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. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

Diagnostic Test

1. DETERMINING IF RELATED ENGINE TPS/APPS DTCS ARE PRESENT

With the scan tool, check Engine DTCs, 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.

Go To 2

2. CHECK IF THE DTC IS CURRENT

With the scan tool, record the DTC EVENT DATA to help identify the conditions in which the DTC was set.
With the scan tool, erase Transmission DTCs.

NOTE: To erase 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 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. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

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 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. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

Test Complete.