GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 Safari - 2WD 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Diagnostic System Check - Horns

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a 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. 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

Scan Tool Does Not Power Up in Data Link Communications

2

  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the BCM.

Does the scan tool communicate with the BCM?

Go to Step 3

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

3

Select the BCM display DTCs function on the scan tool.

Does the scan tool display any DTCs?

Go to Step 4

Symptoms

4

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

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

Go to Diagnostic Trouble Code (DTC) List/Type