FORD 2009 F-150 v.2 - Manual (Page 260)

The GAIN should be set to provide the maximum trailer braking
assistance while ensuring the trailer wheels do not lock when braking.
Locked trailer wheels may lead to trailer instability.
Procedure for adjusting GAIN:
Note: This should only be performed in a traffic free environment at
speeds of approximately 20–25 mph (30–40 km/h).
1. Make sure the trailer brakes are in good working condition,
functioning normally, and properly adjusted. See your trailer dealer if
necessary.
2. Hook up the trailer and make the electrical connections according to
the trailer manufacturer’s instructions.
3. When a trailer with electric brakes is plugged in, the trailer connection
indicator will illuminate blue on the TBC and the GAIN setting display
will illuminate.
4. Use the GAIN adjustment (+/–) buttons to increase or decrease the
GAIN setting to the desired starting point. A GAIN setting of 6.0 is a
good starting point for heavier loads.
5. In a traffic-free environment, tow the trailer on a dry, level surface at
a speed of 20–25 mph (30–40 km/h) and squeeze the manual control
lever completely.
6. If the trailer wheels lockup (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 lockup. If towing a heavier trailer, trailer wheel lockup
may not be attainable even with the maximum GAIN setting of 10.
Explanation of instrument cluster messages:
The TBC interacts with the instrument cluster message center. These
messages, accompanied by a single chime, will be displayed when the
TBC determines a malfunction in the trailer connection, TBC system, or
in the trailer. These messages are listed below:
TRAILER DISCONNECTED: This message is displayed when a trailer
connection was determined and then a disconnection, either intentionally
or unintentionally, has been sensed during a given ignition cycle. It is
also displayed if a trailer fault occurs causing the trailer to appear
disconnected. This message is also displayed during manual activation
without a trailer connected.
TRAILER BRAKE MODULE FAULT: This message is displayed in
response to faults sensed by the TBC. In the event this message is seen,
2009 F-150 (f12)
Owners Guide, 2nd Printing
USA (fus)
Tires, Wheels and Loading
260