Gas
P0123-THROTTLE POSITION SENSOR 1 CIRCUIT HIGH
For complete wiring diagrams refer to Diagrams/Electrical.
- When Monitored:
With the ignition on. Battery voltage greater than 10 volts.
- Set Condition:
Throttle Position Sensor No.1 voltage is greater than 4.8 volts for 25 ms. One Trip Fault. ETC light will illuminate.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. TP SENSOR NO.1 VOLTAGE ABOVE 4.8 VOLTS
NOTE: When this DTC is Active the engine speed, torque, and vehicle speed are limited to a Limp in mode.
NOTE: Make sure the throttle is fully closed and free from binding or carbon build up.
NOTE: If a 5-Volt Supply DTC has also set, diagnose the 5-Volt DTC before continuing.
NOTE: If P2101 is also set, then make sure that the blade moves freely and does not hang up near Wide Open Throttle before trying to repair P0123.
Start the engine.
With a scan tool, read the TP Sensor No.1 voltage.
Is the voltage above 4.8 volts?
Yes
- Go To 2
No
- Go To 8
2. THROTTLE POSITION SENSOR
Turn the ignition off.
Disconnect the Throttle Body harness connector.
Connect a jumper wire between the (K22) TP Signal 1 circuit and the (K922) TP Return circuit in the Throttle Body harness connector.
With a scan tool, monitor the TP Sensor No.1 voltage.
Ignition on, engine not running.
Is the voltage below 0.5 of a volt with the jumper wire installed?
Yes
- Disconnect the Battery when replacing the Throttle Body Assembly. Replace the Throttle Body Assembly. After installation is complete, using a scan tool, select the ETC RELEARN function.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 3
NOTE: Remove the jumper wire before continuing.
3. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
Disconnect the C2 PCM harness connector.
Ignition on, engine not running.
Measure the voltage on the (K22) TP Signal 1 circuit in the Throttle Body harness connector.
Is the voltage above 0 volts?
Yes
- Repair the short to battery voltage in the (K22) TP Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 4
4. (K22) TP SIGNAL 1 CIRCUIT OPEN
Turn the ignition off.
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 (K22) TP Signal 1 circuit from the Throttle Body harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
- Go To 5
No
- Repair the open in the (K22) TP Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
5. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO THE (F855) 5-VOLT SUPPLY CIRCUIT
Measure the resistance between the (K22) TP Signal 1 circuit and the (F855) 5-volt Supply circuit in the Throttle Body harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short between the (F855) 5-volt Supply circuit and the (K22) TP Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 6
6. (K922) TP RETURN CIRCUIT OPEN
Measure the resistance of the (K922) TP Return circuit from the Throttle Body 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 (K922) TP Return circuit.
- Perform the 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 the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
8. THROTTLE FOLLOWER TEST
With a scan tool, perform the Throttle Follower Test.
Monitor the TP Sensor No.1 voltage.
Does voltage start at approximately 0.3 of a volt and go above 4.7 volts with a smooth transition?
Yes
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Disconnect the Battery when replacing the Throttle Body Assembly. Replace the Throttle Body Assembly. After installation is complete, using a scan tool select the ETC RELEARN function.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test