F 350 2WD Super Duty V10-6.8L (2009)
REMOVE the known good relay. INSTALL a new trailer battery charge relay. TEST the system for normal operation.
No
REMOVE the known good relay. GO to AD4.
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AD4 CHECK THE BJB
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Measure the voltage between the trailer battery charge relay pin 30, BJB face side and ground.
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Is the voltage greater than 10 volts?
Yes
GO to AD5.
No
VERIFY the BJB fuse 44 (30A) is OK. If OK, INSTALL a new BJB. TEST the system for normal operation.
If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.
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AD5 CHECK FOR VOLTAGE TO THE TRAILER TOW BATTERY CHARGE RELAY USING THE RELAY GROUND PIN
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Ignition OFF.
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Measure the voltage between the trailer battery charge relay pin 30, BJB face side and the trailer battery charge relay pin 86, circuit GD122 (BK),
BJB face side.
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Is the voltage greater than 10 volts?
Yes
