GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Chevy P32 RV/Van Chassis 🢒 DTC 🢒 DTC P0568 Cruise Control Set Switch Circuit

Object Number: 226924 Size: MF
Engine Controls Components
Engine Controls (Cell 22: Fuel Controls 5)
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

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. A cruise set/coast switch sends an ignition voltage signal to the PCM when the set/coast switch is ON.

Conditions for Running the DTC

The cruise set/coast switch is OFF.

or

The cruise set/coast switch is ON.

Conditions for Setting the DTC

The ignition voltage is on the set/coast switch signal circuit.

or

The set/coast switch is ON for longer than 25.5 seconds.

Action Taken When the DTC Sets
    • The PCM will not illuminate the malfunction indicator lamp (MIL).
    • The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Failure Records.

Conditions for Clearing the MIL/DTC
    • A History DTC will clear after forty consecutive engine warm up cycles, if this or any other emmision related diagnosic does not report any failures.
    • Use of a scan tool will clear the DTC codes.

Diagnostic Aids

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.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

  1. This step determines if the signal circuit is shorted to voltage.

    2.

  2. This step determines if the PCM or switch is at fault.

Step

Action

Value(s)

Yes

No

1

Important: Before clearing any DTCs, use the scan tool Capture Info to save the Freeze Frame and Failure records for reference. The control module's data is deleted once the Clear Info function is used.

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Connect a scan tool.
  2. Turn the ignition ON leaving the engine OFF.
  3. Turn the Cruise switch OFF.

Does the scan tool display the Set switch ON?

--

Go to Step 3

Go to Step 4

3

  1. Turn the ignition ON leaving the engine OFF.
  2. Disconnect the PCM connector containing the Set switch signal circuit.
  3. Probe the Set switch signal circuit at the PCM harness with an J 35616-200 unpowered test lamp connected to chassis ground.

Is the test lamp ON?

--

Go to Step 5

Go to Step 6

4

The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored refer to the applicable DTC table(s) first.

Are any additional DTCs stored?

--

Go to the applicable DTC table

Go to Diagnostic Aids

5
  1. The Set switch signal circuit is shorted to voltage or stuck in the ON position.
  2. Repair the problem as necessary. Refer to Wiring Repairs .

Is the action complete?

--

Go to Step 8

--

6

Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Is the action complete?

--

Go to Step 7

--

7
  1. Using the scan tool, clear the DTCs.
  2. Start the engine.
  3. Allow the engine to idle until the engine reaches normal operating temperature.
  4. Select DTC and the Specific DTC function.
  5. Enter the DTC number which was set.
  6. Operate the vehicle, with the Conditions for Setting this DTC, until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

--

Go to Step 8

Go to Step 2

8

Does the scan tool display any additional undiagnosed DTCs?

--

Go to the applicable DTC table

System OK