P1221

Schematic:

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. Each TP sensor signal voltage increases as the throttle opens. The signal circuit for TP sensors are 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 and TP sensor 2 disagree by more than 0.17 volts.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM will illuminate the MIL during the first trip in which the diagnostic runs and tails.
^ If equipped with traction control, the PCM will command the 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/Failure 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 a scan tool.

DIAGNOSTIC AIDS
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.

Inspect for the following:

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

^ Poor terminal connection.
Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Diagrams.
^ Damaged harness.
Inspect the wiring harness for damage. If the harness appears to be OK, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the display may indicate the location of the fault. Refer to Wiring Repairs in Diagrams.
^ Inspect the PCM and the engine grounds for clean and secure connections.

If the DTC is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set.

TEST DESCRIPTION

Steps 1 - 6:

Steps 7 - 18:

The numbers below refer to the step numbers on the diagnostic table.
18. 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.