GM 30012788 Switch Asm,Stop Lamp & Lock Up (On Esn)

Remove the lower dash panel trim under the steering column, then locate the brake light switch mounted at the top of the brake pedal support and unplug it. Unscrew the locknut on the switch and remove the switch from its bracket. Installation is the reverse of removal; to adjust the switch, loosen the locknut and turn the switch in or out until the plunger clearance is within the specified range. Tighten the locknut once the correct adjustment is achieved.

The ABS is an especially named brake system that keeps the vehicle respond-ability, directional stability and, above all, the optimum negative acceleration under severe brake conditions on most types of roads, pavement, by detecting the rate of the wheels' rotation and modulating the brake line pressure during brak-ing in order to avoid premature locking of the wheels. Two types of systems are utilized: RAWL which controls lockup on the rear wheels and Four Wheel Anti-lock (ABS) which prevents lockup of all four wheels. The actuator assembly includes the master cylinder and control valve(s), which include the dump valve and the isolation valve and functions by means of brake fluid pressure variation in accordance with signal instructions from the control module for RAWL or EBCM for ABS. RAWL has a control module placed behind the area over the driver's side of the instrument panel and the ABS has an electronic brake control module mounted on the passenger side of the brake pedal brace The processor communicates with speed sensors, brake light switch and controls hydraulic line pressure to monitor for faults in the system. The BRAKE message light on the dashboard goes on and there is always a diagnostic code that helps the service technicians tell where the problem is. Rawl speed sensors are located in different places from those of abs, the former has one speed sensor located at the rear differential carrier while the abs has one at each of the front wheels and one at the rear differential carrier. This switch tells the control module if the brake pedal is engaged this is important to the operation of the anti-lock system. If for instance the BRAKE warning light is still on then one should ensure that the parking brake is not on and that there is no problem with the brake hydraulics; if all these are not the problem then the system could be defected. Some of the preliminary checks that can be done by the home mechanic comprise of; checking of the brakes calipers and wheel cylinders, inspection of electrical connectors at the control module assembly, checking of fuses, ensuring that the connections to the speed sensors and brake light switch are correct and tight and damages wiring. In case of failure of these checks, professional diagnosis is advised.