C1218

DTC C1218 Electronic Brake Control Relay Coil Circuit Shorted To Voltage (Part 1 Of 2):

DTC C1218 Electronic Brake Control Relay Coil Circuit Shorted To Voltage (Part 2 Of 2):

Electronic Brake Control Relay Schematic:

CIRCUIT DESCRIPTION
Ignition voltage is supplied through terminal C2 of the Electronic Brake Control Relay. The EBCM then is able to energize the pull-in coil by completing the ground circuit at connector C1 terminal of the EBCM. The magnetic field created closes the Electronic Brake Control Relay contacts and allows battery voltage and current through the Electronic Brake Control Relay terminal C1 to be supplied to the EBCM through connector C2, terminal C, which supplies power to the motors and solenoids.

CONDITIONS FOR SETTING THE DIAGNOSTIC TROUBLE CODE (DTC)
DTC C1218 can be set after the EBCM commands the Electronic Brake Control Relay on. This test monitors the availability of current voltage to the motors and solenoids. A malfunction of this type will not allow voltage to be available to the motors and solenoids; therefore, ABS operation would not be allowed if required.

ACTION TAKEN WHEN THE DTC SETS
A malfunction DTC is stored, ABS is disabled and the amber ABS warning indicator is turned on. The red BRAKE warning indicator is turned on if the rear piston in the ABS brake motor pack is not in the home position.

DIAGNOSTIC AIDS
An intermittent malfunction may be 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 scan tool, as described in Scan Tool Diagnostics in the scan tool manual. Any circuitry that is suspected of 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.

NOTE: J 39200 test leads must be zeroed prior to making any resistance measurements. Refer to J 39200 user's manual.

After diagnosis is complete, clear the DTC's and test drive the vehicle for three (3) drive cycles to verify that the DTC does not reset. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping the vehicle and then turning the ignition to the OFF position.