Parking Brake Warning Lamp: Description and Operation

PARK BRAKE INDICATOR

DESCRIPTION
A park brake indicator is standard equipment on all instrument clusters. The park brake indicator is located near the lower edge of the instrument cluster, to the left of the multi-function indicator display. The park brake indicator consists of stencil-like cutout of the word "PARK" in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents the indicator from being clearly visible when it is not illuminated. A red Light Emitting Diode (LED) behind the cutout in the opaque layer of the overlay causes the "PARK" text to appear in red through the translucent outer layer of the overlay when the indicator is illuminated from behind by the LED, which is soldered onto the instrument cluster electronic circuit board. The park brake indicator is serviced as a unit with the instrument cluster.

OPERATION
The park brake indicator gives an indication to the vehicle operator when the parking brake is applied. This indicator is controlled by a transistor on the instrument cluster circuit board based upon a hard wired input from the park brake switch. The park brake indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster detects that the ignition switch is in the On position. Therefore, the LED will always be off when the ignition switch is in any position except On. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn on the park brake indicator for the following reasons:

- Park Brake Switch Input - Each time the cluster detects ground on the park brake indicator signal circuit (park brake switch closed = park brake applied or not fully released) while the ignition switch is in the On position, the brake indicator is illuminated. The indicator remains illuminated until the brake signal indicator input to the cluster is an open circuit (park brake switch open = park brake fully released), or until the ignition switch is turned to the Off position, whichever occurs first.

The park brake switch on the park brake pedal mechanism provides a hard wired ground input to the instrument cluster circuitry through the park brake indicator signal circuit whenever the park brake is applied or not fully released. The two switches are connected in series between ground and the instrument cluster. The park brake switch and the input circuit to the instrument cluster can be diagnosed using conventional diagnostic tools and methods. For proper diagnosis of the instrument cluster circuitry that controls the park brake indicator, a diagnostic scan tool is required. Refer to the appropriate diagnostic information.