F 350 4WD Super Duty V8-6.4L DSL Turbo (2008)
C6
Test D: DTCs C2806 and C2807 - Trailer Brakes Circuit Failure
Pinpoint Test D: DTCs C2806 and C2807 Trailer Brakes Circuit Failure
NOTE: Carry out all pinpoint tests without a trailer connected to the vehicle.
Refer to Vehicle/Diagrams, Trailer/Camper Adapter for schematic and connector information.
Normal Operation
The braking energy that is provided to the trailer is varied with a pulse width modulated (PWM) signal along circuit CAT19 (BU) that switches
between 0 volt and battery voltage, the higher the duty cycle the more braking power available. The trailer brake control (TBC) module varies the
PWM signal based on various inputs such as the brake pressure transducer, TBC module manual slider switch and the TBC module gain buttons. With
the vehicle stationary and with the manual slider switch fully to the left with a gain of 10, there should be greater than 10-12 volts supplied to trailer
tow C4099-3 circuit CAT19 (BU).
Every 4 seconds the TBC module sends a voltage pulse along circuit CAT19 (BU) to trailer tow C4099-3 to determine whether or not a trailer is
connected to the trailer tow connector.
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C2806 Trailer Brakes Wiring Circuit Short to Voltage - If battery voltage is greater than 16 volts for 200 ms or more, the TBC module shuts off
trailer brake output and then shuts down.
^
C2807 Trailer Brakes Wiring Circuit Short to Ground - If battery voltage is less than 9 volts for 200 ms or more, the TBC module shuts off trailer
brake output and then shuts down.
This pinpoint test is intended to diagnose the following:
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Wiring, terminals or connectors
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TBC module
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Customer trailer
D1
