Brake Warning Switch Description

Fig. 23 Type 1, Combination Valve:

Fig 2 Brake Warning Switch / Hold Off Valve (Cut Away View):

NOTE: This valve is part of a combination valve. See Application and ID.

NOTE: The brake warning light is lit only when the parking brake is applied with the ignition key turned "ON" or when one of the two service brake systems has failed.

The hydraulic system brake warning switch warns the vehicle operator that one of the hydraulic systems has failed.
- A failure in one part of the brake system does not result in failure of the entire hydraulic brake system.
- As an example, failure of the rear brake system will leave the front brake system still operative.

If a pressure loss occurs in one side of the dual brake system, the difference in pressure causes the piston to move to the failed side and latch in that position.
- This will cause the brake system warning light to come on and stay on after the pedal is released.
- After the system is repaired and bled, a moderate application of the brake pedal will hydraulically recenter the piston and automatically turn off the warning light.

CAUTION: Do not disassemble valve to reset the piston.