Engine Code

P0123-THROTTLE POSITION SENSOR #1 HIGH

P0123-Throttle Position Sensor #1 High:

WHEN MONITORED
With the ignition on. Battery voltage greater than 10 volts.

SET CONDITION
Throttle Position Sensor voltage at the PCM is greater than 4.4721 volts. One Trip Fault.

POSSIBLE CAUSES
- (K22) TP signal circuit shorted to (F855) 5 volt supply circuit
- (K22) TP signal circuit shorted to battery voltage
- TP sensor internal failure
- (K22) TP signal circuit open
- (K900) Sensor ground circuit open
- Throttle position sensor
- PCM

Diagnostic Test

1. TP SENSOR VOLTAGE ABOVE 4.5 VOLTS

NOTE: Ensure the throttle is fully closed and free from binding or carbon build up.

Start the engine.
With the scan tool, read the TP Sensor voltage.

Q: Is the voltage above 4.5 volts?

YES: Go To 2
NO: Go To 8

2. (K22) TP SIGNAL CIRCUIT SHORTED TO (F855) 5 VOLT SUPPLY CIRCUIT

Turn the ignition off.
Disconnect the TP Sensor harness connector.
Disconnect the PCM harness connector.
Measure the resistance between the (K22) TP Signal circuit and the (F855) 5 Volt Supply circuit in the TP Sensor harness connector.

Q: Is the resistance below 100 ohms?

YES: Repair the short to the (F855) 5 volt Supply circuit in the (K22) TP Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 3

3. (K22) TP SENSOR SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

Turn the ignition off.
Disconnect the TP Sensor harness connector.
Ignition on, engine not running.
Measure the voltage of the (K22) TP Signal circuit in the TP Sensor harness connector.

Q: Is the voltage above 5.2 volts?

YES: Repair the short to battery voltage in the (K22) TP Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 4

4. TP SENSOR INTERNAL FAILURE

Turn the ignition off.
Disconnect the TP Sensor harness connector.
Connect a jumper wire between the (K22) TP Signal circuit and the (K900) Sensor ground circuit.
With the scan tool, monitor the TP Sensor voltage.
Ignition on, engine not running.

Q: Is the voltage below 0.5 of a volt?

YES: Replace the Throttle Position Sensor. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 5

5. (K22) TP SENSOR SIGNAL CIRCUIT OPEN

Turn the ignition off.
Disconnect the TP harness connector.
Disconnect the PCM harness connector.

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 circuit from the TP harness connector to the appropriate terminal of special tool #8815.

Q: Is the resistance below 5.0 ohms?

YES: Go To 6
NO: Repair the open in the (K22) TP Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

6. (K900) SENSOR GROUND CIRCUIT OPEN

Turn the ignition off.
Disconnect the TP Sensor harness connector.
Disconnect the PCM harness connector.

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 (K900) Sensor ground circuit from the TP Sensor harness connector to the appropriate terminal of special tool #8815.

Q: Is the resistance below 5.0 ohms?

YES: Go To 7
NO: Repair the open in the (K900) Sensor ground circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

7. PCM TP SENSOR SIGNAL CIRCUIT

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

If there are no possible causes remaining, view repair.

Repair
Replace and program the Powertrain Control Module. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

8. THROTTLE POSITION SENSOR SWEEP

Ignition on, engine not running.
With the scan tool, monitor the TP Sensor voltage.
Slowly open the throttle from the idle position to the wide open throttle position.

Q: Does voltage start at approximately 0.7 of a volt and go above 3.5 volts with a smooth transition?

YES: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Replace the Throttle Position Sensor. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test