GM Service Manual Online
For 1990-2009 cars only

Object Number: 255756  Size: SF
ABS Components
Antilock Brake System Schematics
Handling ESD Sensitive Parts Notice

Circuit Description

Ignition voltage is supplied to terminal 86 of the Electronic Brake Control Relay. The above condition enables the EBCM to energize the pull in coil by completing the ground circuit at connector terminal 2 of the EBCM.

The magnetic field created closes the Electronic Brake Control Relay contacts. The magnetic field also allows battery voltage and current through the Electronic Brake Control Relay terminal 30 to be supplied to the EBCM through connector terminal C. Connector terminal C supplies power to the EBCM, which supplies power to the motors and solenoids.

Conditions for Setting the DTC

DTC C1217 determines if the Electronic Brake Control Relay energizes when the Electronic Brake Control Relay should not energize. The above malfunction would not allow the Electronic Brake Control Relay to remove power to the ABS system.

If a second malfunction occurs, that requires the Electronic Brake Control Relay to turn OFF, the second malfunction cannot be removed if the Electronic Brake Control Relay cannot be controlled.

Action Taken When the DTC Sets

    • A malfunction DTC stores.
    • ABS remains functional.

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTCs function is used.
    • 100 drive cycles pass with no DTCs detected. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping and then turning the ignition OFF.

Diagnostic Aids

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction.

Clear the DTCs after completing the diagnosis.

Test drive the vehicle for three drive cycles in order to verify that the DTC does not reset.

Use the following procedure in order to complete one drive cycle:

  1. Start the vehicle.
  2. Drive the vehicle over 16 km/h (10 mph).
  3. Stop the vehicle.
  4. Turn the ignition switch to the OFF position.

Test Description

  1. This test determines if the EBCM is capable of controlling the electronic brake control relay as commanded.

  2. This test ensures that the electronic brake control relay or control circuit are not shorted to ground.

  3. This test ensures that the electronic brake control relay or control circuit are not shorted to ground.

  4. This test determines if the malfunction is due to the EBCM.

Step

Action

Value(s)

Yes

No

Important: Zero the J 39200 test leads before making any resistance measurements. Refer to the J 39200 user's manual.

1

Was the ABS Diagnostic System Check performed?

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Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Turn the ignition switch to the OFF position.
  2. Install a Scan Tool .
  3. Turn the ignition switch to the ON position.
  4. Do not start the engine.

  5. Use the Relay Test function under Special Functions of the Scan Tool in order to command the Electronic Brake Control Relay OFF.

Does the Scan Tool indicate that the Electronic Brake Control Relay is OFF, and is the voltage within the specified voltage range?

0-5 V

Go to Step 12

Go to Step 3

3

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the EBCM connector.
  3. Turn the ignition switch to the ON position.
  4. Do not start the engine.

  5. Use the J 39200 in order to measure the voltage between the EBCM connector terminal 2 and the battery positive terminal.

Is the voltage within the specified voltage?

0-2 V

Go to Step 4

Go to Step  7

4

  1. Turn the ignition switch to the OFF position.
  2. Inspect the following components:
  3. • The EBCM connector terminal 2
    • The remaining terminals of the EBCM connector
  4. Inspect the above components for the following conditions:
  5. • Damage
    • Poor terminal contact
    • Terminal corrosion

Are there signs of poor terminal contact, corrosion, or damaged terminals?

--

Go to Step 8

Go to Step 5

5

Use the J 39200 in order to measure the resistance between the EBCM connector terminal 2 and ground.

Is the resistance within the specified range?

OL

(Infinite)

Go to Step 6

Go to Step 9

6

  1. Reconnect the EBCM connector.
  2. Turn the ignition switch to the ON position.
  3. Do not start the engine.

  4. Use the Scan Tool in order to look for DTCs.

Does DTC C1217 set as a current DTC?

--

Go to Step 11

Go to Step 12

7

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the Electronic Brake Control Relay.
  3. Use the J 39200 with the J 35616 in order to measure the voltage between the Electronic Brake Control Relay connector terminal 85 and the battery positive terminal.

Is the voltage within the specified range?

0-2 V

Go to Step 10

Go to Step 9

8

Replace all of the terminals or connectors that exhibit signs of poor terminal contact, corrosion, or damaged terminal(s). Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

9

Repair the short to ground in CKT 1632.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

10

Replace the Electronic Brake Control Relay. Refer to Electronic Brake Control Relay Replacement .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

11

Replace the EBCM. Refer to Electronic Brake Control Module Replacement .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

12

The malfunction is intermittent or is not present at this time.

Refer to Diagnostic Aids for more information.

Is the action complete?

--

System OK

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