Antilock Braking System (ABS)

Fig. 343 Code 15: Electronic Brake Control Relay Contact Circuit Shorted To Battery Or Always Closed:

Electronic Brake Control Relay Contact Circuit Shorted To Battery Or Always Closed:

Circuit Description:
Ignition voltage is supplied through terminal "85" of the electronic brake control relay. The EBCM is then able to energize the pull-in coil by completing the ground circuit at terminal "22" of the EBCM. The magnetic field created closes the electronic brake control relay contacts and allows battery voltage and current to be supplied to the EMB's and EBCM, which supplies power to the motors and solenoids.

DTC Will Set When:
DTC 15 can be set only before the EBCM commands the relay "ON." This test determines if the electronic brake control relay is energized when it should not be. This malfunction would not allow the electronic brake control relay to remove power to the ABS. If a second malfunction were to occur that requires the electronic brake control relay to be turned "OFF," that malfunction cannot be removed if the relay cannot be controlled. The malfunction must be present for three consecutive ignition cycles before the DTC is set.

Action Taken:
A malfunction DTC is stored. ABS is not disabled and the "ABS" warning lamp will remain "OFF."

DTC Chart Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Indicates if the EBCM is capable of controlling the electronic brake control relay as commanded.
2. Checks for voltage at terminal "A" of the 2-way EBCM harness connector. If voltage is present, the malfunction exists in the electronic brake control relay and/or its circuitry.
3. Checks for a short to voltage in the switched battery input circuit.
4. Ensures the malfunction is not due to a short to BATTERY in the switched battery input circuit with EBCM connected.

Diagnostic Aids:
An "intermittent" malfunction is most likely caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.

The frequency of the malfunction can be checked by using the enhanced diagnostic function of the Tech 1.

Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.