Circuit Description
The cruise control switch is an input to the engine control module (ECM). The ECM monitors the cruise control switch signal circuit in order to detect when a cruise control function has been requested. The ECM detects a specific voltage signal on the cruise control set/coast and resume/accelerate switch signal circuit when a cruise control function switch is activated, with each switch having a different predetermined voltage value.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0568 Cruise Control Set Switch Circuit
Conditions for Setting the DTC
| • | The engine is running. |
| • | Battery voltage is greater than 7.9956 voltage. |
| • | The ECM detects the switch is switching too quickly or stuck for too long. |
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM will record operating conditions at the time the diagnostic fail. This information will be stored in the Freeze Frame and Failure Records buffers. |
| • | A history DTC is stored. |
| • | The A/C compressor operation will be disabled while the low voltage indication exists. |
Conditions for Clearing the MIL/DTC
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | DTCs can be cleared by using the scan tool. |
| • | Disconnecting the ECM battery feed for more than 10 seconds |
Diagnostic Aids
Perform the following in order to avoid misdiagnosis:
| • | Rotate the steering wheel to both steering stops and activate each cruise control switch separately. With a scan tool, observe the associated cruise control switch parameter. This will help eliminate the possibility of an internally open or shorted contact coil. |
| • | Ensure that the resume/accel switch is not stuck or sticking in the engaged position. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
Does the Cruise Resume/Accel. Switch parameter display On? | Go to Step 3 | Go to Diagnostic Aids | |
3 |
Does the Cruise Resume/Accel. Switch parameter display On? | Go to Step 4 | Go to Step 5 |
4 | Test the cruise control resume/accel switch signal circuit for a short to voltage. Did you find and correct the condition? | Go to Step 9 | Go to Step 6 |
5 | Inspect for poor connections at the harness connector of the cruise control switch. Refer to Testing for Intermittent Conditions and Poor Connections . Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
6 | Inspect for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections . Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
7 | Replace the ECM. Refer to Control Module References for ECM replacement, setup, and programming. Did you complete the replacement? | Go to Step 9 | -- |
8 | Replace the cruise control switch. Did you complete the replacement? | Go to Step 9 | -- |
9 |
Does the DTC reset? | Go to Step 2 | System OK |
