P0568

Circuit Description
The cruise Set/Coast switch is an input to the Throttle Actuator Control (TAC) Module. The cruise information is supplied to the PCM via the serial data circuit. This input allows the PCM/TAC module to control and hold a requested speed. The Cruise Set/Coast switch sends ignition voltage to the TAC module when the switch is closed (ON). This DTC sets if the PCM/TAC module senses a voltage on the Set/Coast switch circuit when the voltage is not expected.

Conditions for Running the DTC
The Cruise switch is ON.

Conditions for Setting the DTC
The TAC module detects the Set/Coast switch is ON for longer than 90 seconds.

Action Taken When the DTC Sets
^ The PCM stores the DTC information into memory when the diagnostic runs and fails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
^ The cruise is disabled.

Conditions for Clearing the MIL/DTC
^ A last test failed (current DTC) clears when the diagnostic runs and does not fail.
^ A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
^ Use a scan tool in order to clear the MIL/DTC.

Diagnostic Aids

Important:
^ Remove any debris from the PCM/TAC module connector surfaces before servicing the PCM/TAC module. Inspect the PCM/TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM/TAC modules.
^ For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A. Using this kit prevents damage to the harness/component terminals.
^ The following may cause an intermittent:
- Poor connections.
- Mis-routed harness.
- Rubbed through wire insulation.
- Broken wire inside the insulation.
^ Inspect for a set/coast switch stuck in the engage position or the signal circuit is shorted to voltage.
^ Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This isolates when the DTC failed.
^ For an intermittent, refer to Symptoms. Symptom Related Diagnostic Procedures

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if condition is present.
3. This step determines if the switch is at fault.
4. This step determines if the circuit is shorted to a voltage.