Brake Lamp: Description and Operation

STOP LAMPS

The STOP LP fuse in the engine wiring harness junction block supplies battery positive voltage to the normally open stop lamp switch. When the driver presses the brake pedal, the switch contacts close and battery positive voltage is supplied to both the VECHMSL fuse and the TRCHMSL fuse. On the pickup only, voltage is also supplied to the CHMSL relay in the underhood fuse block which energizes the relay. The energized CHMSL relay supplies battery positive voltage to the multifunction turn signal switch. The utility is not equipped with the CHMSL relay therefore battery positive voltage to the multifunction turn signal switch is supplied directly from the from the stop lamp switch. The current flow from the multifunction turn signal switch continues to the stop lamps which are grounded at G475 and G422 on the pickup and G450 on the utility. The center high mounted stop lamp (CHMSL) is grounded at G202 on the pickup and G450 on the utility.