F 150 4WD V8-4.6L VIN 8 (2010)
When there is no input to the TBC module from the stoplamp switch or the manual sliding lever, the module continually sends a low voltage pulse
(approximately 0.3 volt) along circuit CAT19 (BU) to pin-3 of the 7-pin trailer tow connector every 4 seconds to determine whether or not a trailer is
connected.
The factory 7-pin trailer tow connector is attached with a bracket to the rear bumper of the vehicle or to the trailer hitch (if equipped). The 7-pin trailer
tow connector acts as a jumper connection between C439A (female) and the trailer electrical connector (female).
-
DTC C2806 (Trailer Brakes Wiring Circuit Short to Voltage) - If the TBC module voltage on circuit CAT19 (BU) is equal to or greater than 9
volts for 200 ms or more, while not braking, the TBC module sends the TRAILER FAULT message to the Instrument Cluster (IC), shuts off trailer
brake output and then shuts down.
-
DTC C2807 (Trailer Brakes Wiring Circuit Short to Ground) - If the TBC module voltage on circuit CAT19 (BU) drops by more than 20% for
200 ms or more during a braking event, or for 1.5 ms or more during an on-demand self test, the TBC module sends the TRAILER FAULT
message to the IC, shuts off trailer brake output and then shuts down. This DTC can also be set if the trailer brakes draw more than 28 amps for 20
ms or more.
This pinpoint test is intended to diagnose the following:
-
Wiring, terminals or connectors
-
TBC module
-
Customer trailer
PINPOINT TEST C: THE MESSAGE CENTER DISPLAYS TRAILER FAULT
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.
NOTE: Make sure the trailer brakes are electric-magnet actuated drum-type brakes before proceeding with this pinpoint test.
-------------------------------------------------
C1 CHECK THE MESSAGE IN THE MESSAGE CENTER
-
Verify that a trailer is not connected to the trailer tow connector.
-
Ignition ON.
-
Allow the TBC module time to wake up and prove out.
-
Observe the message center.
-
Does the message center display TRAILER FAULT?
Yes
GO to C2.
No
SEND the trailer to an authorized camper/trailer repair center.
-------------------------------------------------
C2 CHECK THE TRAILER TOW CONNECTOR
-
Ignition OFF.
-
Disconnect the 7-pin trailer tow connector from C439A and inspect both connectors for:
-
water intrusion.
-
corrosion.
-
pushed-out pins.
-
spread terminals.
-
Is the connector OK?
Yes
CONNECT the 7-pin trailer tow connector to C439A. GO to C3.
No
