TBC Fault - Diesel Forum - TheDieselStop.com
Towing and Hauling Towing and hauling with Ford diesel trucks and vans.

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post #1 of 9 (permalink) Old 05-16-2009, 10:19 PM Thread Starter
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TBC Fault

I have an 05 Ford F450 with the tow command. Truck has 19k on it and does not get driven in the winter. When I went to start it, the TBC Fault warning came on with no trailer. When I just hooked it to my 6 ton Hudson trailer the brakes will not come on by pressing the brake pedal. Every once in a while one bar will light up then go out when you stomp the brake. Works if you do it by hand. Any ideas on what is up?
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post #2 of 9 (permalink) Old 05-17-2009, 03:32 AM
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Hum...Maybe mice ate your trailer harness or weather got into it. Get your multimeter and start hunting.

Good luck.

99' f350 Crew, Long, 4x4, 7.3, Auto, 4.56 w/ Detroits, 37's and a bunch of other stuff.
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post #3 of 9 (permalink) Old 05-17-2009, 05:50 PM
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Sounds like a fuse. check under the dash and under the hood - 2 places.

I also found this:

Ford Tow Command Module setup and adjustment.


In the 2006 F250/350/450 Owner's Guide, the Tow Command System is referred
to as the "Integrated trailer brake controller." Here are the instruction
for this device (I cannot post the pictures here, go get the manual to see
them - page 157):

Integrated trailer brake controller (if equipped)

Your vehicle may be equipped with a fully integrated electronic Trailer
Brake Controller (TBC). When used properly, the TBC helps ensure smooth and
effective trailer braking by powering the trailer's electric brakes with a
proportional output based on the towing vehicle's brake pressure.

The Ford TBC can only be used with trailers having electric-actuated drum
brakes (one to four axles) and not hydraulic surge or
electric-over-hydraulic types. It is the responsibility of the customer to
ensure that the trailer brakes are adjusted appropriately, functioning
normally and all electric connections are properly made.

The TBC user interface consists of the following:

1. +/- (GAIN adjustment buttons): Pressing these buttons will adjust the TBC's
power output to the trailer brakes (in 0.5 increments). The GAIN setting can
be increased to a maximum of 10.0 or decreased to a minimum of 0 (no trailer
braking). Pressing and holding a button will raise or lower the setting
2. Trailer connection indicator: This lamp indicates trailer electrical
connection status.
. When a successful trailer connection is detected, the indicator will
be green.
. If the electrical connection is lost, the indicator will flash red. If
the connection is lost while the vehicle is stationary, the indicator will
turn off after 30 seconds. If the connection is lost while the vehicle is
moving, the indicator will flash until the ignition is turned off, then on
. If no electrical connection is detected after the ignition is turned
on, pressing a GAIN adjustment button will display the GAIN setting. Sliding
the manual control will display the GAIN setting, OUTPUT bar graph and light
the trailer indicator red.
3. GAIN setting display: Shows the current GAIN setting. This will
illuminate when a trailer is connected, flash if the trailer becomes
disconnected, or remain off if no trailer is connected.
4. OUTPUT bar graph: When the vehicle's brake pedal is pushed, or when the
manual control is activated, green bar indicators will illuminate to
indicate the amount of power going to the trailer brakes relative to the
brake pedal or manual control input.
5. Manual control lever: Slide the control lever to the left to activate
power to the trailer's electric brakes independent of the tow vehicle's
brakes (see the following Procedure for adjusting GAIN section for
instructions on proper use of this feature). If the manual control is
activated while the brake is also applied, the greater of the two inputs
determines the power sent to the trailer brakes.
.. Stop Lamps: Activating the TBC manual control lever will illuminate both
the trailer brake lamps and the tow vehicle brake lamps (presuming proper
trailer electrical connection). Pressing the vehicle brake pedal will also
illuminate both trailer and vehicle brake lamps.


The GAIN setting is used to set the TBC for the specific towing condition
and should be changed as towing conditions change. Changes to towing
conditions include trailer load, vehicle load, road conditions
and weather. 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 green on the TBC and the GAIN setting display will
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
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 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 (if equipped with message center) or CHECK TRAILER (if
equipped with mini message center): 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. This message
is also displayed during manual activation without a trailer connected.
TBC FAULT: This message is displayed in response to faults sensed by the
TBC. In the event this message is seen, please take your vehicle to an
authorized dealer for diagnosis and repair. The TBC may still function, but
performance may be degraded.
TRAILER FAULT: The TBC is capable of determining certain faults in the
vehicle wiring and trailer wiring/brake system. These faults do not mean
there is anything wrong with the TBC. This message is displayed when one of
the following faults has occurred:
. Short circuit on the electric brake output wire: If the TRAILER FAULT
message is displayed with no trailer connected, the problem is with the
vehicle wiring from the TBC to the 7-pin connector in 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.
. Trailer brake overload: The trailer's brakes are drawing too much
current; consult your trailer dealer for assistance.
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
. 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.
. The TBC interacts with the brake system of the vehicle, including ABS,
in order to reduce the likelihood of trailer wheel lockup.Therefore, if
these systems are not functioning properly the TBC may
not function at full performance.
. When the vehicle is turned off, the TBC Output is disabled and the
display is shut down. Reactivation of the ignition from 3 (OFF) to 4 (ON)
will awaken the TBC module.
. The TBC is only a factory or dealer installed item. Ford is not
responsible for warranty or performance of the TBC due to misuse or customer

Bruce & Carolyn Wittmeier

2001 Ford F250 PSD, Ext cab, Shortbed, Island Blue/Silver, 4X4 Off-road, SOF Auto, Alum Wheels, DP-Tuner 40/80/120HP, Chrome Step, Line-X bedliner, Jordan Ultima 2020, AirLift 5000 Airbags, DiPricol gauges
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post #4 of 9 (permalink) Old 05-17-2009, 08:32 PM Thread Starter
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I checked the fuses, connections, and for mice. I hauled my L48 Kubota today. Works a little off the brake pedal. A few bars come on then go off while the brake is applied. Works fine when you manually slide the bar. Maybe a brake switch? Guess its off to the dealer.
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post #5 of 9 (permalink) Old 05-18-2009, 12:33 PM
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At least you have maintained a sense of humor about it

I was thinking that when you get a few bars with the brake pedal this may be a boost setting like the Pridigy. I just dont know enough about the IBC.

I wouldnt think it was the brake pedal switch or it normally wouldnt work at all.

You might disconnect your battery cable(s) from your truck to see if it will reset.

Let us know what you find.

Bruce & Carolyn Wittmeier

2001 Ford F250 PSD, Ext cab, Shortbed, Island Blue/Silver, 4X4 Off-road, SOF Auto, Alum Wheels, DP-Tuner 40/80/120HP, Chrome Step, Line-X bedliner, Jordan Ultima 2020, AirLift 5000 Airbags, DiPricol gauges
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post #6 of 9 (permalink) Old 05-23-2009, 10:11 AM
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Did you find out what the problem was. Mine just had the same problem
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post #7 of 9 (permalink) Old 05-27-2009, 05:10 AM
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I had to disconnect the tbc on mine. it keeps telling me "trailer disconnected" and has that annoying beep. It's hard to take it seriouslu when there isn't a trailer connected to start with. I think it is in the dash wireing b/c every time I hit the dash near the tbc it does it. any ideas?

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post #8 of 9 (permalink) Old 05-28-2009, 11:57 AM
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Originally Posted by 04titancc View Post
I had to disconnect the tbc on mine. it keeps telling me "trailer disconnected" and has that annoying beep. It's hard to take it seriouslu when there isn't a trailer connected to start with. I think it is in the dash wireing b/c every time I hit the dash near the tbc it does it. any ideas?
Beat it some more. I have that problem with my cb in the roof mounted console.

2003 Ford F-350 Crew Cab L/B/Dually XLT FX4 7.3L/Auto- Gooseneck Hitch Fifth Wheel Rails, Firestone Air Bags/ Toolbox
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post #9 of 9 (permalink) Old 06-03-2009, 06:34 PM
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Mines been acting up for about 2 years now, it still works but always starts with a TBC fault. The controllers made before mid March 05 were defective. These are the ones that don't work in reverse or anything less than 15mph. Replace the controller with the updated version, problem will probably go away. Don't bother asking Ford to help out, I already tried.

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