E 450 V8-5.4L (2009)
Trailer Lamps
Pinpoint Tests
Pinpoint Test T: The Trailer Lamps Are Inoperative - Trailer Stop/Turn Lamp
Refer to Wiring Diagram Set 95, Trailer/Camper Adapter for schematic and connector information. See: Diagrams/Electrical Diagrams/Diagrams By
Number
Refer to Wiring Diagram Set 11, Fuse and Relay Information for schematic and connector information. See: Diagrams/Electrical Diagrams/Diagrams By
Number
Normal Operation
The trailer tow LH stop/turn relay coil receives voltage through circuit CLS18 (GY/BN) when the vehicle LH rear stoplamp is illuminated. When the
trailer tow LH stop/turn relay is energized, the voltage is routed to the trailer tow connector through circuit CAT06 (YE).
The trailer tow RH stop/turn relay coil receives voltage through circuit CLS19 (VT/OG) when the vehicle RH rear stoplamp is illuminated. When the
trailer tow RH stop/turn relay is energized, the voltage is routed to the trailer tow connector through circuit CAT09 (GN).
The Battery Junction Box (BJB) fuse 48 (20A) supplies voltage to the switch side of both trailer tow stop/turn relays through circuit SBB48 (VT/RD).
The trailer tow stop/turn relay coils are grounded through circuit GD123 (BK/GY).
This pinpoint test is intended to diagnose the following:
-
Fuse
-
Wiring, terminals or connectors
-
Trailer tow stop/turn relay
-
Trailer tow connector
-
Trailer
PINPOINT TEST T: THE TRAILER LAMPS ARE INOPERATIVE - TRAILER STOP/TURN LAMP
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the
connector.
NOTE: Before beginning diagnostics, visually inspect the trailer tow connector for signs of corrosion or damage. Repair or install a new trailer tow
connector as required.
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T1 DETERMINE IF BOTH TRAILER STOP/TURN LAMPS ARE INOPERATIVE
-
Apply the brake pedal while observing the trailer lamps.
-
Are both trailer stop/turn lamps inoperative?
Yes
VERIFY the BJB fuse 48 (20A) is OK. If OK, REPAIR circuit SBB48 (VT/RD) for an open. TEST the system for normal operation. If not OK, REFER
to the Wiring Diagrams to identify the possible causes of the circuit short.
No
For an inoperative LH trailer lamp, GO to T2.
For an inoperative RH trailer lamp, GO to T8.
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T2 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (LH TURN)