Brake Warning Lamp Operation

The ABS "BRAKE" warning lamp alerts the driver about low hydraulic accumulator pressure and/or reservoir fluid level As mentioned earlier in this section, the reservoir cap or body contains a fluid level sensor. The contacts will close when the fluid level is low, completing the lamp circuit. Also, the pressure switch has contacts for the "BRAKE" warning lamp circuit, which will close when accumulator pressure is low. The "BRAKE" warning lamp circuit may also be completed by the parking brake switch (when applied) and by the ignition switch in the "crank "position.


1986 Oldsmobile, Buick, and Cadillac C-body cars have a "BRAKE" warning lamp circuit with an additional timer/flasher module (Figure 2-20). This device will flash the "BRAKE"warning lamp if the pump relay contacts are closed for more than three minutes.


1988-to-present Oldsmobile Toronado and Buick Riviera/Reatta use a "BRAKE" warning lamp circuit in which the fluid level sensor and pressure switch are logic inputs to the BCM (Body Control Module). The BCM sends this input data to the IPC (Instrument Panel Cluster), which will operate the lamp (Figure 2-21). The IPC may also display driver messages related to the condition.