F 550 4WD Super Duty V10-6.8L (2009)
Trailer Lamps: Initial Inspection and Diagnostic Overview
Special Tools Used With Diagnostics
Trailer Lamps
Principles of Operation
Trailer Lamps
Principles of Operation
NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).
The trailer lamps and trailer battery charge are supplied power by relays that are energized to correspond with the exterior lighting and ignition switch
functions of the vehicle.
If the vehicle is not equipped with the factory manufactured trailer electric brake control module, the vehicle supplies circuitry to support the installation
of an aftermarket trailer electric brake controller (installed by the customer). To support the aftermarket trailer electric brake controller, the vehicle
circuitry only supplies voltage, ground, stoplamp switch input and a brake controlling circuit to the trailer tow connector. The trailer electric brakes
themselves are controlled by the aftermarket trailer brake controller and not the vehicle itself.
For diagnostics and a description of the factory manufactured trailer brake control system, refer to Trailer Brake Control Module. See: Trailer Brake
Control Module/Testing and Inspection
Inspection and Verification
Trailer Lamps
Inspection and Verification
1. Verify the customer concern.
2. Verify the exterior lighting system of the vehicle is operating correctly. If not, refer to the appropriate pinpoint test.
3. Visually inspect for obvious signs of electrical damage.
Visual Inspection Chart
