Powertrain Control Module (PCM), NGC
P0123-THROTTLE POSITION SENSOR 1 CIRCUIT HIGH
For a complete wiring diagram refer to the wiring information Electrical Diagrams.
- When Monitored:
With the ignition on. Battery voltage greater than 10 volts.
- Set Condition:
Throttle Position Sensor No.1 voltage is greater than the maximum acceptable value. One Trip Fault. ETC light will illuminate.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
1. ACTIVE DTC
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.
1. Start the engine and allow it to reach operating temperature.
2. With the scan tool select View DTCs.
NOTE: If the DTC does not reset it may be necessary to test drive the vehicle.
NOTE: If the P2123-APP Sensor 1 Circuit High DTC is also Active, diagnose the P2123 before continuing with the P0123 diagnostic procedure.
Is the DTC Active at this time?
Yes
- Go To 2
No
- Go To 8
2. THROTTLE POSITION SENSOR
1. Turn the ignition off.
2. Disconnect the Throttle Body harness connector.
3. Ignition on, engine not running.
4. With a scan tool, monitor the TP Sensor No.1 voltage.
5. Connect a jumper wire between the (K22) TP Signal 1 circuit and the (K922) TP Sensor Ground circuit in the Throttle Body harness connector.
NOTE: The sensor voltage should be approximately 0.0 volts (plus or minus.1 volt) with the jumper wire in place.
Does the scan tool display the voltage as described above?
Yes
- Verify that there is good pin to terminal contact in the Throttle Body and Powertrain Control Module connectors. If OK, replace the Throttle Body Assembly. Disconnect the Battery when replacing 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 VOLTAGE
1. Turn the ignition off.
2. Disconnect the C2 PCM harness connector.
3. Ignition on, engine not running.
4. Measure the voltage on the (K22) TP Signal 1 circuit in the Throttle Body harness connector.
Is the there any voltage present?
Yes
- Repair the short to 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
1. 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 PCM Pinout Box 8815 to perform diagnosis.
2. 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 (K855) 5-VOLT SUPPLY CIRCUIT
1. Measure the resistance between the (K22) TP Signal 1 circuit and the (K855) 5-volt Supply circuit in the Throttle Body harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short between the (K855) 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 SENSOR GROUND CIRCUIT OPEN
1. Measure the resistance of the (K922) TP Sensor Ground 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 Sensor Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
7. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Throttle Body and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Throttle Body and Powertrain Control Module connectors.
4. Search for any Technical Service Bulletins that may apply.
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
1. With a scan tool, perform the ETC Throttle Follower Test.
2. Monitor the TP Sensor No.1 voltage.
Does the voltage start at approximately 0.7 of a volt and increase to approximately 4.3 volts with a smooth transition?
Yes
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition Test
No
- Verify that there is good pin to terminal contact in the Throttle Body and Powertrain Control Module connectors. If OK, replace the Throttle Body Assembly. Disconnect the Battery when replacing 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.