GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2004 🢒 Grand Prix 🢒 Engine 🢒 Engine Controls - 3.8L (L26 and L32) 🢒 Diagnostic System Check - Cruise Control

Description

The Cruise Control Diagnostic System Check is an organized approach to identifying a condition created by an electronic control system failure. The Diagnostic System Check directs the service technician to the next logical step in diagnosing the concern. Understanding the system, the table, and using it correctly, reduces diagnostic time and prevents misdiagnosis. For a review of the cruise control system, refer to Cruise Control Description and Operation .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Lack of communication may be due to a malfunction in the class 2 serial data circuit. The specified procedure will determine the particular condition.

    2.

  2. The presence of DTCs which begin with U indicates that some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

Step

Action

Yes

No

1

Install a scan tool.

Does the scan tool power up?

Go to Step 2

Go to Scan Tool Does Not Power Up in Data Link Communications

2

  1. Turn the ignition ON, with the engine OFF.
  2. Attempt to establish communication with the following modules:
    3. • Body control module (BCM)
    • Powertrain control module (PCM)
    • Electronic brake control module (EBCM)

Does the scan tool communicate with the modules listed above?

Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

3

Select the DTCs function on the scan tool for the following modules:

    • Body control module (BCM)
    • Powertrain control module (PCM)
    • Electronic brake control module (EBCM)

Does the scan tool display any DTCs?

Go to Step 4

Go to Symptoms - Cruise Control

4

Does the scan tool display any DTCs which begin with a U?

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

Go to Step 5

5

Does the scan tool display DTC B1327, P0560, or P0620?

Go to Diagnostic Trouble Code (DTC) List in Engine Electrical

Go to Diagnostic Trouble Code (DTC) List