P1121

Circuit Description

The Throttle Position (TP) sensor is mounted on the throttle body/TAC assembly. The sensor is actually two individual Throttle Position sensors within one housing. Two separate signal, ground and reference circuits are used in order to connect the TP sensor assembly and the Throttle Actuator Control (TAC) Module. The TP sensor 1 signal voltage increases as the throttle opens. The signal circuit for TP Sensor is pulled up to reference voltage.

Conditions for Running the DTC

^ DTCs P0606, P1517, P1518 are not set.
^ The ignition switch is in the crank or run position.
^ The ETC serial data is operational.

Conditions for Setting the DTC

^ TP sensor 1 voltage is less than 0.34 volts or greater than 4.4 volts as observed on the scan tool.
^ All of the above conditions met for less than 1 second.

Action Taken When the DTC Sets

^ The PCM will illuminate the MIL during the first trip in which the diagnostic runs and fails.
^ If equipped with traction control, the PCM will command the Electronic Brake and Traction Control Module (EBTCM) via the serial data circuit to turn OFF traction control and illuminate the TRACTION OFF lamp.
^ The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records data.

Conditions for Clearing the MIL/DTC

^ The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic has been run and passed.
^ The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using the Scan Tool.

Diagnostic Aids

Important: Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing/replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

^ The following may cause an intermittent:
- Poor connections. Check for adequate terminal tension. Refer to Wiring Repairs in Diagrams for proper procedure.
- Corrosion
- Mis-routed harness.
- Rubbed through wire insulation.
- Broken wire inside the insulation.
- Inspect the connectors for signs of water intrusion. When this occurs, multiple DTCs should be set and no circuit or component problems can be located.
^ For an intermittent, refer to Symptoms. Symptom Related Diagnostic Procedures
^ If a repair is completed and the DTC was cleared using a scan tool on the same ignition cycle, the default action will not clear until an ignition cycle has occurred.
^ When the TAC module detects a problem within the ETC System the PCM receives a message across serial data and more than one ETC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info.

Test Description

The numbers below refer to the step numbers on the Diagnostic Table.

2. If the scan tool indicates YES, the problem is within the TP sensor 1 Circuit. If the scan tool indicates NO the problem is within the throttle actuator circuits or the battery feed circuit.
6. This step determines if the problem is with the TAC or the circuit.
10. In this step the power has been removed from the signal circuit. The step determines if there is a short to voltage on the signal circuit.
12. In this step the power has been removed from the signal circuit. The step determines if there is a short to voltage on the reference circuit.
33. When the TAC module detects a problem within the ETC System the PCM receives a message across serial data and more than one ETC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info.