F 350 2WD Super Duty V10-6.8L (2009)
Yes
INSTALL a new SJB. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. TEST the system for normal
operation.
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Pinpoint Test B: The Horn Is Always On
Horn
Pinpoint Tests
Pinpoint Test B: The Horn Is Always On
Refer to Wiring Diagram Set 44, Horn/Cigar Lighter for schematic and connector information. See: Diagrams/Electrical Diagrams/Diagrams By
Number
Normal Operation
The Smart Junction Box (SJB) supplies the switched and control voltage to the horn relay (part of the SJB). When the driver air bag is pressed against
the steering wheel, ground is supplied from circuit GD116 (BK/VT) to the horn relay coil through circuit SRH01 (YE/RD), energizing the horn relay.
The horn relay then provides voltage to the horn through circuit CRH02 (BU/WH), enabling the horn to sound.
This pinpoint test is intended to diagnose the following:
-
Wiring, terminals or connectors
-
Steering wheel switch harness
-
Clockspring
-
Horn switch (part of the driver air bag module)
-
SJB
PINPOINT TEST B: THE HORN IS ALWAYS ON
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the
connector.
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B1 CHECK THE SJB HORN OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE
-
Ignition OFF.
-
Disconnect: SJB C2280e.
-
Does the horn continue to sound?
Yes
REPAIR circuit CRH02 (BU/WH) for a short to voltage. TEST the system for normal operation.
No
GO to B2.
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B2 CHECK THE HORN SWITCH INPUT
-
Disconnect: SJB C2280b.
-
Connect: SJB C2280e.
-
Does the horn continue to sound?
Yes
