Pinpoint Test G: The Trailer Brakes Are Always Engaged
WARNING: This page is about a different car, the 2006 Ford Pickup, 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
Use the flex probe kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes.
- G1 CHECK THE TRAILER BRAKE CONTROL (TBC) MODULE OUTPUT
- Key in START position.
- Enter the following diagnostic mode on the scan tool: TBC BOO PID.
- Monitor the TBC BOO PID while firmly pressing and releasing the brake pedal.
- Does the TBC BOO PID agree with the stoplamp switch position?
Yes : GO to G2.
No : VERIFY brake switch operation. If OK, GO to G3. If not OK, GO to EXTERIOR LIGHTING .
- G2 CHECK CIRCUIT 43 (DB) FOR VOLTAGE NOTE: Every 4 seconds a voltage pulse is applied as a trailer connectivity test.
- Key in OFF position.
- Disconnect: Trailer Tow C4099.
- Key in ON position.
- Make sure the brake pedal is not pressed and the manual slider switch is not being applied.
- Measure the voltage between trailer tow C4099-3, circuit 43 (DB), harness side and ground.
- Is steady voltage indicated?
Yes : GO to G3.
No : The TBC module and vehicle wiring are operating correctly. SEND the trailer to an authorized camper/trailer repair center.
- G3 CHECK CIRCUIT 43 (DB) FOR A SHORT TO VOLTAGE
- Key in OFF position.
- Disconnect: TBC Module C2142a.
- Key in ON position.
- Measure the voltage between trailer tow C4099-3, circuit 43 (DB), harness side and ground.
- Is voltage present?
Yes : REPAIR circuit 43 (DB) for a short to voltage. TEST the system for normal operation
No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector or the customer's trailer. TEST the system for normal operation.