P0121

P0121-THROTTLE POSITION SENSOR 1 PERFORMANCE

Special Tools:










For a complete wiring diagram, refer to the Wiring Information

- 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 Position Sensor 1 circuit input voltage is implausible.





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

Diagnostic Test

1. ACTIVE DTC
1. Start the engine and allow it to idle.

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 may result in possible serious or fatal injury.

2. With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

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

2. CHECK THE (F855) 5-VOLT SUPPLY CIRCUIT VOLTAGE




1. Turn the ignition off.
2. Disconnect the Throttle Body harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (F855) 5-Volt Supply circuit in the Throttle Body harness connector.

Is the voltage between 4.8 and 5.2 volts?

Yes

- Go To 3

No

- Repair the (F855) 5-Volt Supply circuit for an open or short circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

3. CHECK THE (K922) TPS SENSOR GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Disconnect the PCM C2 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 the GPEC Diagnostic Adaptor to perform the diagnosis.

3. Connect the (10436).
4. Measure the resistance of the (K922) TPS Sensor Ground circuit between the Throttle Body harness connector and the GPEC Adaptor.

Is the resistance below 5.0 Ohms?

Yes

- Go To 4

No

- Repair the (K922) TPS Sensor Ground circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. CHECK THE (K22) TPS SIGNAL 1 CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K22) TPS Signal 1 circuit between the Throttle Body harness connector and the GPEC Adaptor.

Is the resistance below 5.0 Ohms?

Yes

- Go To

No

- Repair the (K22) TPS Signal 1 circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. CHECK THE (K122) TPS SIGNAL 2 CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K122) TPS Signal 2 circuit between the Throttle Body harness connector and the GPEC Adaptor.

Is the resistance below 5.0 Ohms?

Yes

- Go To 6

No

- Repair the (K122) TPS Signal 2 circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. THROTTLE BODY
1. Replace the Throttle Body. Throttle Body - Removal.
2. Turn the ignition on

3. With the scan tool, erase DTCs.
4. Start the engine and allow it to idle.
5. With the scan tool, view DTCs.

Did the DTC return?

Yes

- Go To 7

No

- Repair complete.
- 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.
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 (PCM). Powertrain Control Module - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.