Expedition 2WD V8-5.4L (2009)
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Is the voltage greater than 10 volts?
Yes
REMOVE the known good relay. INSTALL a new trailer tow turn relay. TEST the system for normal operation.
No
REMOVE the known good relay. GO to Z5.
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Z5 CHECK FOR VOLTAGE TO THE LH STOP/TURN LAMP RELAY COIL
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While applying the brake pedal, measure the voltage between the trailer tow LH turn relay pin 1, circuit CLS18 (GY/BN), BJB face side and
ground.
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Is the voltage greater than 10 volts?
Yes
GO to Z6.
No
REPAIR circuit CLS18 (GY/BN) for an open. TEST the system for normal operation.
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Z6 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE LH STOP/TURN LAMP RELAY
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Measure the voltage between the trailer tow LH turn relay pin 3, circuit SBB45 (GY/RD), BJB face side and ground.
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Is the voltage greater than 10 volts?
Yes
GO to Z7.
No
REPAIR circuit SBB45 (GY/RD) for an open. TEST the system for normal operation.
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Z7 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE LH STOP/TURN LAMP RELAY USING THE RELAY GROUND PIN
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Measure the voltage between the trailer tow LH turn relay pin 3, circuit SBB45 (GY/RD), BJB face side and the trailer tow LH turn relay pin 2,
circuit GD123 (BK/GY), BJB face side.
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Is the voltage greater than 10 volts?
