Dakota 2WD V8-4.7L VIN J (2005)
Parking Brake Warning Lamp: Description and Operation
A brake indicator is standard equipment on all instrument clusters. This indicator is located in the center of the speedometer, in the area below and right
of the speedometer needle hub.
The brake indicator consists of a stencil-like cutout of the word "BRAKE" (all clusters with a miles-per-hour primary speedometer scale), or the
International Control and Display Symbol icon for "Brake Failure" (all clusters with a kilometers-per-hour primary scale) 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 "BRAKE" text or the icon 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 brake indicator is serviced as a unit with the instrument cluster.
The brake indicator gives an indication to the vehicle operator when the parking brake is applied, when there are certain brake hydraulic system
malfunctions as indicated by a low brake hydraulic fluid level condition, or when the brake fluid level switch is disconnected. The brake indicator can
also give an indication when certain faults are detected in the Antilock Brake System (ABS). This indicator is controlled by a transistor on the instrument
cluster circuit board based upon cluster programming, electronic messages received by the cluster from the Controller Antilock Brake (CAB) over the
Controller Area Network (CAN) data bus, and a hard wired input from the park brake switch.
The 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 receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED
will always be off when the ignition switch is in any position except On or Start. The LED only illuminates when it is provided a path to ground by the
instrument cluster transistor. The instrument cluster will turn on the brake indicator for the following reasons:
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Bulb Test - Each time the ignition switch is turned to the On position the brake indicator is illuminated for about four seconds as a bulb test. The
entire bulb test is a function of the CAB.
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Brake Lamp-On Message - Each time the cluster receives a lamp-on message from the CAB, the brake indicator will be illuminated. The CAB
can also send brake lamp-on messages as feedback during ABS diagnostic procedures. The indicator remains illuminated until the cluster receives
a lamp-off message from the CAB, or until the ignition switch is turned to the Off position, whichever occurs first.
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Park Brake Switch Input - Each time the cluster detects ground on the park brake switch sense circuit (park brake switch closed = park brake
applied or not fully released) while the ignition switch is in the On position, the brake indicator flashes on and off. The indicator continues to flash
until the park brake switch sense 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.
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Actuator Test - Each time the instrument cluster is put through the actuator test, the brake indicator will be turned on, then off again during the
bulb check portion of the test to confirm the functionality of the LED and the cluster control circuitry.
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
switch sense circuit whenever the park brake is applied or not fully released. The CAB continually monitors the ABS system circuits and sensors,
including the brake fluid level switch on the brake master cylinder reservoir, to decide whether the system is in good operating condition. The CAB then
sends the proper lamp-on or lamp-off messages to the instrument cluster. If the CAB sends a lamp-on message after the bulb test, it indicates that the
CAB has detected a brake hydraulic system malfunction and/or that the ABS system has become inoperative. The CAB will store a Diagnostic Trouble
Code (DTC) for any malfunction it detects.
For further diagnosis of the brake indicator or the instrument cluster circuitry that controls the LED, refer to testing. The park brake switch input to the
instrument cluster may be diagnosed using conventional diagnostic tools and methods. Refer to the appropriate wiring information. For proper diagnosis
of the brake fluid level switch, the ABS, the CAB, the CAN data bus, or the electronic message inputs to the instrument cluster that control the brake
indicator, a diagnostic scan tool is required.
