GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2004 🢒 Epica 🢒 Brakes 🢒 Antilock Brake System 🢒 Diagnostic System Check - ABS

System Description

The Diagnostic System Check is an organized method of identifying any problems caused by a malfunction in the antilock brake system (ABS)/de-coupled dynamic rear proportioning (DDRP) system.

A service technician should begin the diagnosis of any ABS/DDRP complaint with the Diagnostic System Check. The Diagnostic System Check directs a service technician to the next logical step when diagnosing a complaint.

Serial data is transmitted/received by the electronic brake control module (EBCM) through terminal B6. The EBCM is supplied with constant battery feed voltage through terminals A and B, and switched ignition voltage through terminal A11. The EBCM ground is provided through terminals D and C.

Diagnostic Process

Use the following ordered procedure when servicing the ABS/DDRP system.

  1. Inspect the vehicle for any mechanical conditions related the brake system.
    2. • Brake reservoir fluid level correct
    • Inspect master for fluid for contamination
    • Inspect brake master/modulator for leaks
    • Inspect brake components at all wheels
    • Verify no brake drag exists, brake switch adjustment
    • Verify even brake apply, no pull or lead
    • Inspect for worn/damaged brake pads
    • Inspect for worn/damaged wheel bearings
    • Inspect wheel speed sensors/wiring
    • Inspect exciter rings for damage
    • Inspect tires for tread depth/wear
    • Road test the vehicle to verify the complaint.
  2. Perform the Diagnostic System Check and proceed to the applicable diagnostic trouble chart as necessary.
  3. Clear the ABS DTCs after all of the system malfunctions have been corrected.

Step

Action

Yes

No

1
  1. Connect or install all previously disconnected or removed components if applicable.
  2. Turn ON the ignition switch.
  3. Install the applicable scan tool into the data link connector (DLC) and attempt to communicate with the electronic brake control module (EBCM).

Does the scan tool communicate with the EBCM?

Go to Step 2

Go to Step 4

2

Were any DTCs stored current or history?

Go to Step 3

Go to Step 6

3
  1. Document current DTCs.
  2. Document history DTCs.
  3. Document enhanced history data such as:
    4. • Number of times each DTC set
    • Number of times since each DTC first set
    • Speed when each DTC set
    • Other enhanced data which may assist with diagnosis
  4. Do not clear the DTCs prior to fully documenting the information from the scan tool.
  5. Refer to the applicable DTCs.

Were any DTCs stored?

Go to Diagnostic Trouble Code (DTC) List

Go to Step 6

4

Does the scan tool communicate with other modules on the data line?

Refer to No Communication with Electronic Brake Control Module

Go to Step 5

5
  1. Repair the DLC harness.
  2. Replace the DLC harness as needed.

Did you complete the repair?

System OK

--

6
  1. Turn the ignition switch OFF.
  2. Wait 10 seconds.
  3. Turn the ignition switch ON.
  4. Observe the amber ABS lamp when the key is turned ON.

Did the ABS warning lamp and brake warning lamp turn ON for 3 seconds and then turn OFF (bulb test)?

System OK

Go to Step 7

7

Did any lamp stay on after the bulb test?

Go to appropriate Lamp ON Diagnostic Chart

Go to Step 8

8

Did any lamp not illuminate during the bulb test?

Go to appropriate Lamp Inoperative Diagnostic Chart

System OK