Brake warning lamps. Brake lamp switch

Brake warning lamps

DESCRIPTION

The red brake warning lamp and amber ABS warning lamp are located in the instrument cluster.

The red brake warning lamp is used to alert the driver of a hydraulic fault or that the parking brake is applied. For the RWAL system, the red brake warning lamp also is used to alerts the driver of a problem with the RWAL system.

Fig. 5 Data Link Connector - Typical

1 - 16-WAY DATA LINK CONNECTOR

OPERATION

The red brake warning lamp illuminates when a message is sent over the bus to the cluster to illuminate the bulb. A ground for the bulb is provided when:

• The parking brake is applied and the park brake switch is actuated.
• A hydraulic fault has occurred and the pressure differential switch is actuated.
• A RWAL fault has occurred.

The amber ABS warning lamp is used to alert the driver of an RWAL problem and identify DTCs stored in the CABs memory.

Brake lamp switch

DESCRIPTION

The plunger type brake lamp switch is mounted on a bracket attached to the brake pedal support.

CAUTION: The switch can only be adjusted during initial installation. If the switch is not adjusted properly a new switch must be installed.

OPERATION

The primary function of the switch is to turn on the brake lamps during braking. The switch is also used to send signals to components that must know when the brakes are applied, such as the Powertrain Control Module (PCM), which uses the signal to cancel speed control. The CAB uses the brake switch signal to monitor brake pedal application. When the switch contacts open (brakes applied), the CAB receives the brake applied signal. The CAB then monitors the RWAL system to anticipate the need for an RWAL stop.