Circuit Description
The cruise Set/Coast switch is an input to the fuel control portion
of the PCM. These inputs allow the PCM to control and hold a requested speed.
Cruise Set/Coast switch sends a ignition voltage signal to the PCM when
the Set/Coast switch is ON.
Conditions for Running the DTC
| • | The PCM performs this DTC diagnostic continuously. |
| • | The Cruise Control ON/OFF switch in the OFF position. |
or
| • | The PCM performs this DTC diagnostic continuously. |
| • | The Cruise Control ON/OFF switch in the ON position. |
Conditions for Setting the DTC
| • | Ignition voltage on Set/Coast request signal circuit. |
| • | All of the diagnostic set conditions met for 2 seconds. |
or
| • | Set/Coast request switch ON for longer than 25.5 seconds. |
| • | All of the diagnostic set conditions met for 2 seconds. |
Action Taken When the DTC Sets
| • | The PCM disallows all cruise control inputs. |
| • | TCC shift schedules may be affected. |
| • | The PCM will not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM records the operating conditions at the time the diagnostic
fails. This information stores in the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | A History DTC will clear after forty consecutive warm-up
cycles, if this or any other emission related diagnostic does not report any
failures. |
Diagnostic Aids
Important: Remove any debris from the PCM module connector surfaces before servicing
the PCM module. Inspect the PCM module connector gaskets when diagnosing/replacing
the module. Ensure that the gaskets are installed correctly. The gaskets
prevent contaminate intrusion into the PCM module.
If the Set/Coast switch is stuck in the ON position or the driver is
holding the Set/Coast switch ON for longer than 25.5 seconds, DTC P0568
will set. DTC P0568 only checks the signal circuit for a short
to voltage.
