The electronic brake control module (EBCM) receives a signal from the trailer Antilock Brake System (ABS) module over the Ignition 1 voltage circuit. The EBCM applies ground to the trailer ABS indicator control circuit in order to turn ON the TRAILER ABS indicator.

Schematic Reference

Air Antilock Brake System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

ABS Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for EBCM

1. Ignition OFF for 5 seconds.
2. Ignition ON, observe the Driver Information Center (DIC) Trailer ABS Indicator. The Indicator should illuminate then turn OFF.

1. Ignition OFF, disconnect the electronic brake control module (EBCM) harness containing the trailer ABS indicator control circuit at the EBCM.
2. Ignition ON, verify that a test lamp illuminates between the driver information center (DIC) ignition 1 circuit terminal 1 and ground.

⇒	If the test lamp does not illuminate, test the ignition 1 circuit for a short to ground or an open/high resistance. If the circuit tests normal, and the ignition 1 voltage circuit breaker is open, test the EBCM trailer ABS indicator control circuit terminal 11 for a short to ground.

⇒	If the test lamp illuminates, test the Ignition 1 voltage circuit for a open between the EBCM and the trailer wiring harness connector. If the circuit through the trailer tests normal, inspect for devices that may interfere with the ABS signal refer to Checking Aftermarket Accessories.

3. Verify the scan tool instrument cluster special function display test trailer ABS Lamps.

⇒	If the trailer ABS lamp does not illuminate, test the EBCM control circuit terminal 11 for a short to voltage.

⇒	If the circuit tests normal, replace the EBCM.

4. Ignition OFF, disconnect the telltale circuit board circuit connector containing the trailer ABS indicator control circuit within the driver information center (DIC).

⇒	If the trailer ABS indicator does not turn OFF, test the ABS indicator control circuit for a short to ground and open/high resistance. If the circuit tests normal, replace the telltale circuit board.

5. Install a 3 A fused jumper wire between the EBCM control circuit terminal 11 and the DIC Ignition 1 voltage.
6. Ignition OFF, Install a test lamp between the EBCM trailer ABS Indicator Control terminal 11 and ground.
7. Ignition ON, verify that a test lamp does illuminate between the EBCM trailer ABS Indicator Control terminal 11 and ground.

⇒	If not the specified value, test the signal circuit, for an open/high resistance. If the circuit tests normal, replace the EBCM.

8. If all circuits test normal, replace the tell tale circuit board.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.