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Powertrain Control Module (PCM)






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 TPS 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 and battery voltage greater than 10.4 volts.

- Set Condition:
The Powertrain Control Module (PCM) detects that the Throttle Body input voltage is above the maximum acceptable threshold.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

Diagnostic Test

1. DTC IS ACTIVE

NOTE: Diagnose and repair any Throttle Body circuit, system voltage, or sensor supply voltage DTCs before continuing with this test.

1. Start the engine and allow it to reach operating temperature.

WARNING:
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

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 status Active for this DTC?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. (F855) 5 VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the Throttle Body harness connector.
3. Disconnect the PCM C2 harness connector.
4. Turn the ignition on.
5. Measure the voltage of the (F855) 5 Volt Supply circuit in the Throttle Body harness connector.

Is there any voltage present?

Yes

- Repair the short to voltage in the (F855) 5 Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO VOLTAGE
1. Measure the voltage of the (K22) TP Signal 1 circuit in the Throttle Body harness connector.

Is 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 SHORTED TO THE (F855) 5 VOLT SUPPLY CIRCUIT
1. Turn the ignition off.
2. Measure the resistance between the (K22) TP Signal 1 circuit and the (F855) 5 Volt Supply in the Throttle Body harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short between the (K22) TP Signal 1 circuit and the (F855) 5 Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 5

5. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO THE (K447) ETC MOTOR (+) CIRCUIT
1. Measure the resistance between the (K22) TP Signal 1 circuit and the (K447) ETC Motor (+) in the Throttle Body harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short between the (K22) TP Signal 1 circuit and the (K447) ETC Motor (+) circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 6

6. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO THE (K448) ETC MOTOR (-) CIRCUIT
1. Measure the resistance between the (K22) TP Signal 1 circuit and the (K448) ETC Motor (-) in the Throttle Body harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short between the (K22) TP Signal 1 circuit and the (K448) ETC Motor (-) circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 7

7. (K22) TP SIGNAL 1 CIRCUIT OPEN
1. Measure the resistance of the (K22) TP Signal 1 circuit between the Throttle Body harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 8

No

- Repair the open in the (K22) TP Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

8. (K922) TP SENSOR GROUND CIRCUIT OPEN
1. Measure the resistance of the (K922) TP Sensor Ground circuit between the Throttle Body harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 9

No

- Repair the open in the (K922) TP Sensor Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

9. THROTTLE BODY
1. Turn the ignition off.
2. Connect the PCM C2 harness connector.
3. Connect a jumper wire between the (K22) TP Signal 1 circuit and the (K922) TP Sensor Ground circuit in the Throttle Body harness connector.
4. Turn the ignition on.
5. With a scan tool, read the Throttle Body voltage.

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. Throttle Body - Removal. Disconnect the Battery when replacing the Throttle Body Assembly. After installation is complete, using a scan tool select ETC RELEARN function.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 10

10. 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.
4. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
5. Look for the data to change or for the DTC to reset during the wiggle test.
6. Perform any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

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

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