GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C Sierra - 2WD 🢒 Body and Accessories 🢒 Cruise Control 🢒 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. • 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

Important:: The engine may start during the following step. Turn the engine OFF as soon as you have observed the Crank power mode.

  1. With a scan tool, access the Class 2 Power Mode in the Diagnostic Circuit Check.
  2. Rotate the ignition switch through all positions while observing the System Power Mode parameter. Refer to the Serial Data Power Mode table within the Body Control System Description and Operation in Body Control Systems, for a complete list of the power mode state that correspond to each ignition switch positions.

Does the System Power Mode parameter reading match the ignition switch positions for all switch positions?

Go to Step 4

Go to Power Mode Mismatch in Body Control System

4

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

    • Powertrain Control Module (PCM)
    • Electronic Brake Control Module (EBCM)

Does the scan tool display any DTCs?

Go to Step 5

Go to Symptoms - Cruise Control

5

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 6

6

Does the scan tool display DTC P0562, P0563, P0615, P0621, P0622, P1637, or P1638?

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

Go to Diagnostic Trouble Code (DTC) List