S15/T15 Sonoma P/U 2WD V6-262 4.3L VIN W CPI (1994)
Brake Warning Indicator: Initial Inspection and Diagnostic Overview
Battery voltage is supplied to the Brake Indicator through the IGN/GAU Fuse and the PNK/BLK (39) wire when the Ignition Switch is in RUN or
START. Ground is provided through the TAN/WHT (33) wire by the Park Brake Warning Switch, Brake Pressure Warning Switch or the Electronic
Hydraulic Control Unit (EHCU) also called Antilock Electronic Brake Control Module.
The Park Brake Warning Switch closes when the Parking Brake is applied. The Brake Indicator lights to alert the driver.
The Brake Pressure Warning Switch closes to light the Brake Indicator when there is low brake fluid pressure in one of the two hydraulic brake systems.
This could be caused by a leak in one of the brake lines. This can only be accomplished after the system has been repaired.
The Rear-Wheel Antilock Brake Module grounds the Brake Indicator when the Module senses a malfunction in the Antilock Brake System. The
Four-Wheel Antilock Brake Module grounds the Brake Indicator when the module senses certain malfunctions in the hydraulic portion of the system.
The Four-Wheel Antilock Brake Module grounds the Antilock Indicator when the module senses a malfunction in the electrical or electronic portion of
the system. Brake voltage input is supplied to both Modules through the Stoplamp Switch whenever the brakes are applied.
