GM Service Manual Online
For 1990-2009 cars only

Object Number: 397517  Size: MF
ABS Components
Cell 44: Indicators and Stoplamp/BTSI Switch
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Cell 50: Class 2 Serial Data Line

Circuit Description

The instrument cluster controls the operation of the ABS indicator. The EBCM/EBTCM reports the desired status of the ABS indicator via class 2 serial data messages. The ABS indicator signal circuit is a back-up reporting circuit to the class 2 serial data messages. The EBCM/EBTCM supplies ground through the circuit when the ABS is operating properly. When there is a problem with ABS that should turn on the ABS indicator, the EBCM/EBTCM opens the ABS indicator signal circuit. If there is a problem with the ABS class 2 serial data messages, the instrument cluster uses the ABS indicator signal to determine if the ABS indicator should be illuminated. Using the serial data messages and back-up circuit, the instrument cluster decides whether to turn on the ABS indicator.

Conditions for Setting the DTC

The EBCM/EBTCM commands the ABS indicator ON when one of the following conditions are detected:

    • An open
    • A short to ground
    • A short to voltage

Action Taken When the DTC Sets

    • A malfunction DTC is stored.
    • The ABS is not disabled.
    • The ABS indicator remains OFF.

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present and you used the scan tool Clear DTC function.
    • The EBCM/EBTCM does not detect the DTC in 50 drive cycles.

Diagnostic Aids

    • It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
    • An intermittent malfunction can be caused by poor connections, broken insulation, or a wire that is broken inside the insulation.
    • If an intermittent malfunction exists, refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

Test Description

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

  1. This step tests if the instrument cluster can operate the ANTILOCK indicator.

  2. This step tests for a short to ground in CKT 852.

  3. This step tests for a short to voltage in CKT 852.

  4. This step tests for an open in CKT 852.

Step

Action

Value(s)

Yes

No

1

Was the ABS Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Turn the ignition switch to the RUN position with the engine OFF.
  2. Using a scan tool, read the ABS/TCS and instrument cluster diagnostic trouble codes (DTCs).

Is DTC U1300 or DTC U1301 set?

--

Go to DTC U1300 Class 2 Short to Ground or DTC U1301 Class 2 Short to Battery in Data Link Communications

Go to Step 3

3

  1. Select SBM special functions on the scan tool.
  2. Run the instrument cluster bulb check.

Does the ANTILOCK indicator turn ON then OFF?

--

Go to Step 4

Go to Step 10

4

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the electronic brake (and traction) control module (EBCM/EBTCM).
  3. Connect the J 39700 universal pinout box using the J 39700-25 cable adapter to the EBCM/EBTCM harness connector only.
  4. Disconnect the instrument cluster connector.
  5. Using the J 39200 , measure the resistance between the J 39700 terminal 3 and terminal B.

Is the resistance equal to the specified value?

OL (Infinite)

Go to Step 6

Go to Step 5

5

Repair the short to ground in CKT 852. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

6

  1. Turn the ignition switch to the RUN position with the engine OFF.
  2. Using the J 39200 , measure the voltage at terminal 3 of the J 39700 .

Is the voltage more than the specified value?

1 V

Go to Step 8

Go to Step 7

7

  1. Turn the ignition switch to the OFF position.
  2. Connect a fused jumper wire between the instrument cluster harness connector terminal B13 and a good ground.
  3. Using the J 39200 digital multimeter (DMM), measure the resistance between the J 39700 terminal 3 and terminal B.

Is the resistance less than the specified value?

5 ohms

Go to Step 11

Go to Step 9

8

Repair the short to voltage in CKT 852. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

9

Repair the open in CKT 852. Refer to Wiring Repairs in Wiring Systems.

Is the circuit repair complete?

--

Go to Diagnostic System Check - ABS

--

10

Suspect the instrument cluster. Refer to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges and Console.

Is the diagnosis complete?

--

Go to Diagnostic System Check - ABS

--

11

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

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--