P1121

DTC P1121 TP Sensor CKT Intermittent High Voltage




Circuit Description
The Throttle Position (TP) sensor is a three wire potentiometer using a 5 volt reference, a ground and a signal circuit. The TP sensor signal circuit detects voltage changes on the potentiometer (variable resistor) as the throttle angle changes. The TP sensor signal voltage varies from 0.6 volts at idle to approximately 4.6 volts at wide open throttle. The TP sensor is one of the primary inputs to the VCM. Its input is important to most engine and transmission functions.

This DTC is designed to detect intermittent high signal voltage on the TP sensor signal circuit.

Conditions for Running the DTC
The engine is running.

Conditions for Setting the DTC
The VCM detects an intermittent high TP sensor voltage while the engine is running.

Action Taken When the DTC Sets
The VCM stores the DTC in History if the VCM detects an intermittent problem.

Conditions for Clearing the MIL/DTC
- A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22 °C (40 °F) from the startup coolant temperature and the engine coolant temperature exceeds 70 °C (160 °F) during the same ignition cycle.
- Use the scan tool Clear Information function.

Diagnostic Aids
The scan tool reads the throttle position in volts. The scan tool should read about 0.45 to 0.85 volt with the throttle closed and the ignition switch turned ON or at idle. The voltage should increase at a steady rate as the throttle is moved toward the Wide Open Throttle (WOT).

Also, some scan tools will read the throttle angle. 0% = closed throttle. 100% = WOT.

Scan the TP sensor while depressing the accelerator pedal with the engine turned OFF and the ignition turned ON. The display should vary from about 0.5 volts (500 mV) when the throttle was closed to about 4.5 volts (4500 mV) when the throttle is held at WOT position.

This DTC could set if the TP ground circuit is intermittently open or the TP signal circuit is intermittently shorted to voltage. If the high voltage reading is present, additional sensor circuit voltage codes could be set. Refer to any non- Intermittent DTCs that are set.

Refer to Symptoms.

An intermittent may be caused by any of the following conditions:
- A poor connection
- Rubbed through wire insulation
- A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis.

If a repair is necessary, then refer to Wiring Repairs or Connector Repairs.

Steps 1 - 4:

Steps 5 - 8:

Step 9:

Test Description
The numbers below refer to the step numbers in the diagnostic table.

2. If the TP sensor voltage is greater than 4.7 volts, then the conditions for the DTC are still present.
3. If any other non-intermittent DTCs are set go there first.