GM Service Manual Online
For 1990-2009 cars only

Object Number: 891311  Size: MF

Circuit Description

The cruise control clutch is used to engage and release the cruise control cable drive mechanism from the cruise control motor. To command the clutch ON, engaged, the engine control module (ECM) provides ground to the cruise control module via the Cruise Control Servo Clutch Control circuit. When the cruise control clutch is commanded ON, engaged, the feedback voltage at the ECM should be low. If the cruise control clutch is commanded ON, and the feedback voltage on the Cruise Control Servo Clutch Control circuit is high, DTC P1587 will set indicating a short to voltage exists.

Conditions for Running the DTC

Continuous when cruise control clutch commanded on (engaged).

Conditions for Setting the DTC

    • The ECM detects high feedback voltage when the cruise control clutch is commanded OFF.
    • The condition exists for 500 ms.

Action Taken When the DTC Sets

    • The ECM stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.

Conditions for Clearing the DTC

    • A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
    • A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
    • Use a scan tool in order to clear the DTC.

Diagnostic Aids

To locate an intermittent problem, use the scan tool to command Cruise Clutch ON while monitoring C/C Clutch-High Volt test with ignition ON, engine OFF. The scan tool will display Test Fail when a short to voltage exists in the Cruise Control Servo Clutch Control circuit.

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step determines if the fault is present.

Step

Action

Yes

No

Connector End View Reference: Cruise Control Connector End Views

1

Did you perform the Diagnostic System Check - Cruise Control?

Go to Step 2

Go to Diagnostic System Check - Cruise Control

2

  1. Connect a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Using scan tool command Cruise Clutch ON while monitoring C/C Clutch-High Volt test.

Does the Test Fail?

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn OFF the ignition.
  2. Disconnect the cruise control module at the harness connector.
  3. Connect noid light J 34730-2A Harness Test Lamp between the ignition 1 voltage and Cruise Control Servo Clutch Control circuits at harness connector.
  4. Using a scan tool command Cruise Clutch ON.

Does the test light illuminate?

Go to Step 5

Go to Step 4

4

Inspect Cruise Control Servo Clutch Control circuit for short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the problem?

Go to Step 7

Go to Step 6

5

Replace the cruise control module. Refer to Cruise Control Module Replacement .

Did you complete the repair?

Go to Step 7

--

6

Important: The replacement ECM must be programmed.

Replace ECM. Refer to Engine Control Module Replacement in Engine Controls.

Did you complete the repair?

Go to Step 7

--

7

  1. Use a scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK