Brake Lamp: Description and Operation

Bulb Check
When the ignition switch is first turned to ON (II), the "safety indicator" circuit in the gauge assembly tests the brake system indicator light by supplying a ground for several seconds to turn it on. When the ignition is turned to START (III), the "test during START" circuit tests the light by grounding it. With the ignition switch in ON (II) or START (III), battery voltage is supplied through fuse 5 and the YEL wire to the gauge assembly. With the ignition switch in START (III), battery voltage is supplied through fuse 7 and the BLK/WHT wire to the gauge assembly.