Normal Operation And Fault Conditions
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Through the use of the brake booster vacuum sensor, the ABS module monitors the vacuum in the brake booster. When the vacuum reaches the low side of a predetermined threshold, the ABS module provides a ground for the vacuum pump relay coil to activate the brake vacuum pump. Once the vacuum in the brake booster reaches the high side of a predetermined threshold, the ABS module removes the ground connection for the vacuum pump relay coil, deactivating the brake vacuum pump.
A leak in the brake booster vacuum system, an inoperative relay, an inoperative pump, a short to ground, a short to voltage or an open in the vacuum pump relay or vacuum pump motor circuits can cause the ABS module to set one or more DTCs.