W350 1 Ton Pickup 4WD V8-360 5.9L VIN W 4-bbl (1983)
Brake Fluid Pressure Sensor/Switch: Testing and Inspection
Brake Warning Switch Testing
1. Raise the car on a hoist and open a wheel cylinder bleeder while a helper depresses the brake pedal and observes the warning light.
2. If the light fails to light, inspect for a burned out bulb, disconnected socket, or a broken or disconnected wire at the switch.
3. If the bulb is not burned out and the wire continuity is uninterrupted, check the service brake warning switch operation with a test lamp between
the switch terminal and a voltage source.
4. If light still fails to light, disconnect the brake tubes from the valve assembly and install a new valve assembly.
5. If a new valve is installed, bleed the system.
CAUTIONS:
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Do not disassemble valve to reset the piston.
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The warning switch is not serviced separately. Do not remove the switch or attempt to repair.
NOTE: After repairing and bleeding the brake system, applying the brakes with moderate force will hydraulically recenter the piston and automatically
turn off the warning light.
