GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Epica 🢒 Brakes 🢒 Antilock Brake System 🢒 No Communication with Electronic Brake Control Module

Circuit Description

Serial data is transmitted/received by the electronic brake control module (EBCM) through terminal 7. The EBCM is supplied with constant battery feed voltage through terminals 9 and 25, and switched ignition voltage through terminal 4. The EBCM ground is provided through terminal 8 and 24.

Diagnostic Aids

Typical causes of no communication with the EBCM:

    • Poor terminal contact at the EBCM
    • Loss of EBCM ground to terminal 8 and 24
    • Loss of battery voltage at EBCM terminals 9 and/or 25
    • Loss of ignition voltage at EBCM 4
    • Open/grounded data line
    • Data line with high resistance

Step

Action

Values

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Component Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Turn the ignition switch OFF.
  2. Disconnect the electronic brake control module (EBCM) harness.
  3. Connect a voltmeter to the EBCM harness terminal 9 and then to body ground.

Does the voltage measure within the specified range?

B+

Go to Step 4

Go to Step 3

3
  1. Repair the source of the low voltage to terminal 9.
  2. Inspect for an open fuse, poor terminal contact, or a grounded wire.

Did you find and correct the condition?

--

System OK

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4

Connect a voltmeter to the EBCM harness terminal 25 and then to the body ground.

Does the voltage measure within the specified range?

B+

Go to Step 6

Go to Step 5

5
  1. Repair the source of the low voltage to terminal 25.
  2. Inspect for an open fuse, poor terminal contact, or a grounded wire.

Did you find and correct the condition?

--

System OK

--

6
  1. Turn ON the ignition switch.
  2. Connect a voltmeter to the EBCM harness terminal 4 and then to body ground.

Does the voltage measure within the specified range?

B+

Go to Step 8

Go to Step 7

7
  1. Repair the source of the low voltage to terminal 4.
  2. Inspect for an open fuse, poor terminal contact, or a grounded wire.

Did you find and correct the condition?

--

System OK

--

8
  1. Turn the ignition switch OFF.
  2. Connect an ohmmeter to the EBCM harness terminal 8 and 24 and then to body ground.

Does the resistance measure less than the specified value?

2 Ω

Go to Step 10

Go to Step 9

9
  1. Repair the source of the high resistance between terminal 8 and 24.
  2. Find and inspect the ground location where the circuit is secured to body ground.

Did you find and correct the condition?

--

System OK

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10
  1. Turn OFF the ignition switch.
  2. Verify the EBCM harness is still disconnected from the EBCM.
  3. Connect an ohmmeter to the EBCM harness terminal 7 and the data link connector (DLC) terminal 7.

Does the resistance measure less than the specified value?

2 Ω

Go to Step 12

Go to Step 11

11

Repair the source the high resistance between terminal 7 and DLC terminal 7.

Did you complete the repair?

--

System OK

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12
  1. Turn the ignition switch OFF.
  2. Verify the EBCM harness is still disconnected.
  3. Connect an ohmmeter to the EBCM harness terminal 7 and then to body ground.

Does the resistance measure OL, open circuit?

--

Go to Step 14

Go to Step 13

13

Find and repair the short to ground on the data line.

Did you find and correct the condition?

--

System OK

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14

Replace the EBCM.

Did you complete the replacement?

--

System OK

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