Brake System Warning Light Test
- Brake system warning light should only come on when parking brake is applied with ignition on, or if part of hydraulic brake system fails when brake pedal is applied. BRAKE light will also come on as a bulb test when ignition switch is turned to START position.
- To test parking brake light system, turn ignition on. DO NOT start engine. Apply parking brake. If BRAKE warning light fails to come on, check for burned-out bulb, disconnected bulb socket, or a broken or disconnected wire at parking brake switch. If these items are good, replace parking brake switch.
- Release parking brake. Warning light should go out. If light stays on, check for sticking parking brake cable, grounded switch wires, shorted parking brake warning switch, brake hydraulic system leak or grounded brake warning switch on proportioning valve. Repair as needed.CAUTION: If wheel cylinder bleed screw is opened, ensure brake system is properly bled and master cylinder fluid level is correct.
- To test service brake hydraulic warning system, raise and support vehicle. Attach bleeder hose and fluid catch bottle to a brake wheel cylinder bleed screw. Open bleed screw. Depress brake pedal. BRAKE warning light should come on.
- If BRAKE warning light fails to come on, check warning light wiring circuit by using 12-volt test light to ground brake warning light switch connector on proportioning valve. With ignition on, if BRAKE warning light fails to come on and bulb is not burned out, there is an open in wiring harness. Repair wiring harness as required and retest.
- If BRAKE warning light does come on and wiring harness is okay, replace brake warning switch mounted to proportioning valve.