GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Blazer - 4WD - RHD 🢒 Body and Accessories 🢒 Data Link Communications 🢒 Diagnostic System Check - Cruise Control

Test Description

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

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

    2.

  2. The presence of DTCs which begin with "U" indicate some other module is not communicating on the class 2 serial data circuit. The specified procedure will compile all the available information before tests are perform.

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

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 node.

  1. Access the Class 2 Power Mode in the Diagnostic Circuit Check on the scan tool.
  2. Rotate the ignition switch through all positions while observing the System Power Mode parameter.

Does the System Power Mode parameter reading match the ignition switch position 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:

    • EBCM
    • PCM

Does the scan tool display any DTCs for the modules listed above?

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, P0621, or P0622?

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

Go to Diagnostic System Check - Cruise Control