NGC

P0122-THROTTLE POSITION SENSOR 1 CIRCUIT LOW

For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the ignition on and battery voltage greater than 10.4 volts.

- Set Condition:
The PCM detects that the Throttle Body input voltage is below the minimum acceptable value.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

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.

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.

Start the engine and allow it to reach operating temperature.
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 P2122-APP Sensor 1 Circuit Low DTC is also Active, diagnose the P2122 before continuing with the P0122 diagnostic procedure.

Is the DTC Active at this time?

Yes

- Go to 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. Checking For An Intermittent DTC

2. (F855) 5 VOLT SUPPLY CIRCUIT VOLTAGE

Turn the ignition off.
Disconnect the Throttle Body connector.
Turn the ignition on.
Measure the voltage of the (F855) 5 Volt Supply circuit in the Throttle Body harness connector.
Is the voltage above 4.5 volts?

Yes

- Go to 6

No

- Go to 3

3. (F855) 5 VOLT SUPPLY CIRCUIT SHORTED TO GROUND

Turn the ignition off.
Disconnect the C2 Powertrain Control Module (PCM) connector.
Measure the resistance between ground and the (F855) 5 Volt Supply circuit in the Throttle Body harness connector.
Is the resistance above 1000 ohms?

Yes

- Go to 4

No

- Repair the short to ground in the (F855) 5 Volt Supply circuit.
- Perform the PCM Verification Test. Powertrain Verification Test

4. (F855) 5 VOLT SUPPLY CIRCUIT SHORTED TO THE (K922) TP SENSOR GROUND CIRCUIT
Measure the resistance between the (F855) 5 Volt Supply circuit and the (K922) TP Sensor Ground circuit in the Throttle Body harness connector.
Is the resistance above 100 ohms?

Yes

- Go to 5

No

- Repair the short between the (F855) 5 Volt Supply circuit and the (K922) TP Sensor Ground circuit.
- Perform the PCM Verification Test. Powertrain Verification Test

5. EXCESSIVE RESISTANCE IN THE (F855) 5 VOLT SUPPLY CIRCUIT

Turn the ignition off.
Disconnect the C2 Powertrain Control Module (PCM) connector.
Measure the resistance between ground and the (K22) TP Signal 1 circuit in the Throttle Body harness connector.
Is the resistance above 100 ohms?

Yes

- Go to 7

No

- Repair the short to ground in the (K22) TP Signal 1 circuit.
- Perform the PCM Verification Test. Powertrain Verification Test

7. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO THE (K922) TP SENSOR GROUND CIRCUIT

Measure the resistance between the (K22) TP Signal 1 circuit and the (K922) TP Sensor Ground circuit in the Throttle Body harness connector.
Is the resistance above 100 ohms?

Yes

- Go to 8

No

- Repair the short between the (K22) TP Signal 1 circuit and the (K922) TP Sensor Ground circuit.
- Perform the PCM Verification Test. Powertrain Verification Test

8. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO THE (K124) ETC MOTOR (+) CIRCUIT

Measure the resistance between the (K22) TP Signal 1 circuit and the (K124) 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 (K124) ETC Motor (+) circuit.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 9

9. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO THE (K126) ETC MOTOR (-) CIRCUIT

Measure the resistance between the (K22) TP Signal 1 circuit and the (K126) 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 (K126) ETC Motor (-) circuit.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 10

10. EXCESSIVE RESISTANCE IN THE (K22) TP SIGNAL 1 CIRCUIT

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 between the Throttle Body harness connector and the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?

Yes

- Go to 11

No

- Repair the excessive resistance in the (K22) TP Signal 1 circuit.
- Perform the PCM Verification Test. Powertrain Verification Test

11. THROTTLE BODY
Turn the ignition off.
Connect the Powertrain Control Module (PCM) connector.
Connect a jumper wire between the (K22) TP Signal 1 circuit and the (F855) 5 Volt Supply circuit in the Throttle Body harness connector.
Turn the ignition on.
With the scan tool, read the Throttle Body signal voltage.

NOTE: The sensor voltage should be approximately 5.0 volts (plus or minus.1 volt) with the jumper wire in place.

Turn the ignition off.
Connect a jumper wire between the (K22) TP Signal 1 circuit and the (K922) TP Sensor Ground circuit in the Throttle Body harness connector.
Turn the ignition on.
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. Disconnect the Battery when replacing the Throttle Body Assembly. Replace the Throttle Body Assembly if no problems were found in the connectors. After installation is complete, using a scan tool select the ETC RELEARN function.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 12

12. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Throttle Body and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
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.
Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM Verification Test. Powertrain Verification Test