FORD 2012 F-550 v.1 - Manual (Page 263)

6. If the trailer wheels lock up (indicated by squealing tires), reduce the
GAIN setting; if the trailer wheels turn freely, increase the GAIN setting.
Repeat Steps 5 and 6 until the GAIN setting is at a point just below
trailer wheel lock-up. If towing a heavier trailer, trailer wheel lock-up
may not be attainable even with the maximum GAIN setting of 10.
Explanation of instrument cluster warning messages:
The TBC interacts with the instrument cluster message center to display
the following messages:
TRAILER BRAKE MODULE FAULT: This message is displayed and
accompanied by a single chime, in response to faults sensed by the TBC.
In the event this message is seen, please contact your authorized dealer
as soon as possible for diagnosis and repair. The TBC may still function,
but performance may be degraded.
WIRING FAULT ON TRAILER: This message is displayed when a
Short circuit on the electric brake output wire has occurred. If the
WIRING FAULT ON TRAILER message is displayed and accompanied
by a single chime, with no trailer connected, the problem is with the
vehicle wiring from the TBC to the 7–pin connector at the bumper. If the
message is only displayed with a trailer connected, the problem is related
to the trailer wiring; consult your trailer dealer for assistance. This can
be a short to ground (i.e., chaffed wire) or a short to voltage (i.e., pulled
pin on trailer emergency break-away battery) or trailer brakes drawing
too much current.
Note: Your TBC can be diagnosed by your authorized dealer to
determine exactly which trailer fault has occurred; however, if the fault
is with the trailer this diagnosis is not covered under your Ford
warranty.
Points to Remember:
• Remember to adjust gain setting before using the TBC for the first
time.
• Readjust gain setting on the TBC (according to procedure above)
whenever road, weather and trailer or vehicle loading conditions
change from those that existed when the gain was initially set.
• The sliding lever on the TBC should be used only for manual
activation of trailer brakes to assist with proper adjustment of the
GAIN. Misuse, such as application during trailer sway, could cause
instability of trailer and/or tow vehicle.
• Avoid towing in adverse weather conditions. The TBC does not
provide anti-lock control of the trailer wheels. Trailer wheels can lock
up on slippery surfaces, resulting in reduced stability of trailer and
tow vehicle.
Tires, Wheels and Loading
263
2012 F-250/350/450/550 (f23)
Owners Guide, 1st Printing
USA (fus)