C1248

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(Part 2 Of 2):

Schematic Diagram:

CIRCUIT DESCRIPTION
Voltage is applied to the normally open isolation valves whenever the main relay is energized. An isolation valve closes when the Electronic Brake/Traction Control Module (EBCM/EBTCM) supplies a ground path at the isolation valve control terminal.

The isolation valves are closed only during traction control operations, and are not used during antilock or normal braking conditions. The isolation valves separate (isolate) the front brake hydraulic circuits from the master cylinder and rear brake hydraulic circuits. Once the front brake hydraulic circuits are isolated, pressure can be applied to the front wheels without affecting any other brake hydraulic circuit. The EBTCM turns ON the Brake Pressure Modulator Valve (BPMV) pump motor to apply pressure, and begin cycling the BPMV inlet and outlet valves to modulate pressure.

CONDITIONS FOR SETTING THE DTC
DTC C1248 sets when the EBTCM detects an open or short to ground in the RF isolation valve circuit.

ACTION TAKEN WHEN THE DTC SETS
A malfunction DTC is stored, ABS/TCS is disabled and the ANTILOCK indicator lamp is turned ON.

CONDITIONS FOR CLEARING THE DTC
^ Conditions for the malfunction are no longer present and scan tool clear DTCs function is used.

^ 100 ignition switch key cycles have passed with no malfunctions detected.

DIAGNOSTIC AIDS
It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully inspect wiring may result in misdiagnosis, causing part replacement with reappearance of the malfunction.