P0123
P0123-THROTTLE POSITION SENSOR 1 CIRCUIT HIGH
For a complete wiring diagram, refer to the Wiring Information.
Theory of operation
The Electronic Throttle Control (ETC) system uses two Throttle Position Sensors (TPS) to monitor the throttle blade position. The Throttle Position Sensors 1 and 2 are located within the Throttle Body assembly. Each sensor has a 5-Volt reference circuit, a low reference circuit, and a signal circuit. Processors are also used to monitor the ETC system data. The processors are located within the Powertrain Control Module (PCM). Each signal circuit provides the processors with a signal voltage proportional to throttle blade movement. The processors share and monitor data to verify that the indicated TPS calculation is correct.
- When Monitored:
With the ignition on. Battery voltage greater than 10.0 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. Pre-Diagnostic Troubleshooting Procedure.
1. ACTIVE DIAGNOSTIC TROUBLE CODE (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, read the active 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 the scan tool, monitor the TP Sensor No.1 voltage.
5. Connect a jumper wire between the (K22) TP Sensor No.1 Signal circuit and the (K922) TP Sensor Return 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. Throttle Body - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 3
NOTE: Remove the jumper wire before continuing.
3. (K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Ignition on, engine not running.
4. Measure the voltage on the (K22) TP Sensor No.1 Signal circuit in the Throttle Body harness connector.
Is there any voltage present?
Yes
- Repair the short to voltage in the (K22) TP Sensor No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 4
4. (K22) TP SENSOR NO.1 SIGNAL CIRCUIT OPEN
1. Turn the ignition off.
2. Measure the resistance of the (K22) TP Sensor No.1 Signal circuit from the Throttle Body harness connector to the PCM C2 harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Go To 5
No
- Repair the open in the (K22) TP Sensor No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
5. (K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO THE (F855) 5-VOLT SUPPLY CIRCUIT
1. Measure the resistance between the (K22) TP Sensor No.1 Signal 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 Sensor No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 6
6. (K922) TP SENSOR RETURN CIRCUIT OPEN
1. Measure the resistance of the (K922) TP Sensor Return circuit from the Throttle Body harness connector to the PCM C2 harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Go To 7
No
- Repair the open in the (K922) TP Sensor Return 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. Perform 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 (PCM). PCM/ECM Reprogramming
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
8. THROTTLE FOLLOWER TEST
1. With the scan tool, perform the ETC Throttle Follower Test.
2. Monitor the TP Sensor No.1 voltage.
Does the voltage start at approximately 0.7 Volt and increase to approximately 4.3 Volts with a smooth transition?
Yes
- Perform 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. Throttle Body - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.