DTC 78

CIRCUIT DIAGRAM





INSPECTION PROCEDURE

CIRCUIT DESCRIPTION:
These DTCs identify a solenoid that cannot be energized due to an open in its circuitry, or a solenoid that is always energized due to a short to battery in its circuitry between the driver and solenoid. An open will not allow proper Antilock Brake System (ABS) operation, but the short to battery simply turns the solenoid on. A path for base brakes is still allowed once the motor re-homes and the check ball is lifted off its seat during initialization.

FAILURE CONDITION:
DTCs 76 and 78 can be set only when the solenoid is commanded off. If the Electronic Brake Control Module (EBCM) detects an excessive voltage in the solenoid control circuit, a malfunction exists.

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 TECH-1 as described in "TECH-1 Diagnostics".
Any circuitry that is suspected of causing the intermittent malfunction 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.