E 450 V8-5.4L (2009)
No
REMOVE the known good relay. GO to X4.
-------------------------------------------------
X4 CHECK FOR VOLTAGE TO THE TRAILER TOW BATTERY CHARGE RELAY
-
Measure the voltage between the trailer battery charge relay pin 3, circuit SBB63 (WH/RD), BJB face side and ground.
-
Is the voltage greater than 10 volts?
Yes
GO to X5.
No
VERIFY the BJB fuse 63 (30A) is OK. If OK, REPAIR circuit SBB63 (WH/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.
-------------------------------------------------
X5 CHECK FOR VOLTAGE TO THE TRAILER TOW BATTERY CHARGE RELAY USING THE RELAY GROUND PIN
-
Ignition OFF.
-
Measure the voltage between the trailer battery charge relay pin 3, circuit SBB63 (WH/RD),BJB face side and the trailer battery charge relay pin
2, circuit GD123 (BK/GY), BJB face side.
-
Is the voltage greater than 10 volts?
Yes
GO to X6.
No
REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation.
-------------------------------------------------
X6 CHECK FOR VOLTAGE TO THE TRAILER BATTERY CHARGE RELAY COIL (INOPERATIVE CONDITION)
-
Ignition ON.
-
Measure the voltage between the trailer battery charge relay pin 1, circuit CBP44 (VT), BJB face side and ground.
