Vehicle: 2003 Ford F-250, 4WD, Super
Duty, 7.3L DSL Turbo V-8, VIN F
Problem: When applying the brakes with
doors closed and engine running, the dash and speedometer lamps
dim. When the door is open and the truck is running, the
warning chime sounds when brakes are applied. The problem
does not occur when the brake pedal is released.
NOTE: This truck has a cab guard with
aftermarket brake lamps and lights installed on the guard.
Details: When the tech checked brake lamps,
they all operated normally. Next, he checked some grounds for the
brake lamp switch and they were good at ground #G300. There
were two fuses that fed power to the brake switch: #34 and #18.
The problem stopped when fuse #18 was removed. That fuse fed the
rear brake lamps. NOTE: If a stop lamp bulb
element is broken and shorting against the park lamp element
inside the same bulb, it can cause power to feedback and the
illuminate the dash lights. He disconnected each side of the
aftermarket cab guard lamps individually. He found that one of
the cab guard side lamps was faulty.
Confirmed Repair: The tech replaced that
lamp assembly and the truck’s weird electrical issue was