Brake Warning Indicator

The IPC  uses 3 basic messaged inputs to control the brake warning indicator. The first 2 messages are the parking brake position switch and the brake fluid level switch sent from the BCM  over the Medium Speed Controller Area Network (MS-CAN). The third is the brake warning indicator request message sent from the ABS  module through the BCM  . The BCM  receives the brake warning indicator request from the GWM  over the High Speed Controller Area Network (HS-CAN). The GWM receives the brake warning indicator request from the ABS  module over the Electric Vehicle (EV) High Speed Controller Area Network (HS-CAN).

The parking brake position switch and the brake fluid level switches are hardwired to the BCM  through a single signal circuit while using a separate ground to control the input.

The BCM  provides a reference voltage to both the parking brake position switch and the brake fluid level switch. When the parking brake is applied, the parking brake position switch closes to ground, pulling the parking brake signal circuit low. When a normal brake fluid level condition exists, the brake fluid level switch is closed to ground, pulling the signal circuit voltage low to the BCM  . When a low brake fluid level condition exists, the brake fluid level switch opens to ground, sending the signal circuit high. If the brake fluid level switch is disconnected, the BCM  reference voltage sent to the brake fluid level switch remains high and the brake fluid input is interpreted as a low brake fluid level condition by the BCM  . When a low brake fluid level condition exists, the BCM  sends the brake fluid level low request to the IPC  .

If the brake fluid level drops and opens the brake fluid level switch, the BCM  waits approximately 30 seconds before sending the IPC  the brake fluid level low message to illuminate the brake warning indicator.

When the ABS  module detects a base brake system concern or other ABS  -related concerns that affect the EBD  function, the ABS  module sends the brake warning request to the BCM  . The BCM  then sends the brake warning indicator request to the IPC  to illuminate the brake warning indicator.