C1278

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Part 2 Of 2:

CIRCUIT DESCRIPTION
DTC C1278 identifies a brake solenoid valve that cannot be energized. The malfunction may be caused by one of the following conditions:
^ An open in the solenoid valve circuitry
^ The solenoid valve is always energized due to a short to ground in the solenoid valve circuitry between the driver and the brake solenoid valve.
^ An open will not allow proper ABS operation, but the short to ground simply turns on the brake solenoid valve. A path for base brakes is still allowed once the motor rehomes and the check ball is lifted off its seat during key to RUN initialization.

CONDITIONS FOR SETTING THE DTC
DTC C1278 can set only when the solenoid is commanded off while the Electronic Brake Control Relay is enabled.

A malfunction exists if the EBCM/EBTCM detects the right front brake solenoid valve control circuit voltage is not within specifications.

ACTION TAKEN WHEN THE DTC SETS
A malfunction Diagnostic Trouble Code (DTC) stores. The ABS/ETS/TCS disables. The amber ABS/ETS/TCS warning indicator(s) turn on.

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 DTC(s) detected.

DIAGNOSTIC AIDS
The following conditions may cause an intermittent malfunction:
^ A poor connection
^ Rubbed-through wire insulation
^ A broken wire inside the insulation

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction. Refer to the Scan Tool manual for the procedure.

Thoroughly inspect any circuitry that may cause the intermittent complaint for the following conditions:
^ Backed out terminals
^ Improper mating
^ Broken locks
^ Improperly formed or damaged terminals
^ Poor terminal-to-wiring connections
^ Physical damage to the wiring harness

IMPORTANT: Zero the J 39200 test leads before making any resistance measurements. Refer to the J39200 user's manual.