GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Chevy C Cab/Chassis HD (GMT 400) 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Diagnostic System Check - ABS

Circuit Description

The ABS Diagnostic System Check is an organized approach to identifying problems associated with the EBCM. This must be the starting point for any ABS related concern and will direct you to the next logical step in diagnosing a malfunction. Most system malfunctions are linked to faulty wiring, connections and occasionally, to components. Understanding the ABS system and using the diagnostic tables correctly will reduce diagnostic time and prevent unnecessary parts replacement.

Test Description

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

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

    2.

  2. The presence of DTCs which begin with "U" indicates some other module is not communicating or that the EBCM is not communicating with the PCM on the class 2 serial data circuit. 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 ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the following control modules:
    3. • Powertrain
    • 4WAL 3 Sensor

Does the scan tool communicate with the control modules listed above?

Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Device (PCM) or Scan Tool Does Not Communicate with Electronic Brake Control Module (EBCM) in Data Link Communications

3

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

    • Powertrain
    • 4WAL 3 Sensor

Does the scan tool display any DTCs?

Go to Step 4

Go to Symptoms - Antilock Brake System

4

Does the scan tool display any DTCs which begin with "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 P0500, P0502, P0503, P0562, P0563, P0601-P0607, P1381, P1621, P1627 or P1683?

Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 6.5L (L65) or Diagnostic Trouble Code (DTC) List in Engine Controls - 8.1L

Go to Diagnostic Trouble Code (DTC) List