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The ongoing evolution of anti-lock brakes has spawned yet another new system. Introduced on 1999 Buick Regal and Century, and Chevrolet Tracker, the new Delphi Brake Control (DBC) 7 ABS system is the successor to Delphi's ABSVI (which has been around since 1991 on many General Motors passenger cars). For model year 2000, the new DBC-7 system was added to the Chevrolet Impala, Monte Carlo, Malibu, Cavalier and Venture, Pontiac Sunfire and Montana, and Oldsmobile Cutlass and Silhouette.
Like other newly introduced ABS systems, DBC-7 is a compact, lightweight, low-cost ABS system that combines the controller and valve body in one assembly. It is a nonintegral, four-wheel system for either three or four channel operation, and offers traction control capability.
DBC-7 is totally different than the ABS-IV system GM has used on so many of its passenger cars. Gone are the gear pack and motor driven pistons. DBC-7 uses solenoid valves like other ABS systems manufactured by Bosch, Kelsey-Hayes and Teves, and the controller, valves, solenoids and pump are combined into one compact unit.
The valves and pump are mounted in a metal block called the "Brake Pressure Modulator Valve" or BPMV. This is bolted to the "Electronic Brake Control Module" or EBCM that houses the controller, relay and solenoids that actuate the ABS valves. The unit can be taken apart so the BPMV or EBCM can be replaced separately if needed.
The Brake Pressure Modulator Valve has one inlet (apply) valve and one outlet (release) valve for each brake channel, plus two accumulators (one for each brake circuit). So the BPMV contains a total of six ABS valves for three channel system applications, eight ABS valves for four channel systems, or 10 ABS valves if the vehicle has TCS traction control. The inlet valves are normally open, and the outlet valves are normally closed. The solenoid for each valve is energized when the EBCM provides a ground to complete the circuit.
The GM passenger car applications are all four channel ABS systems, so each of the four BPMV outlets is connected to the brake line for a separate wheel. The lines are color coded for identification: left rear is purple, right rear is yellow, left front is red, and right front is green.
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