Pinpoint Test C : The Message Center Displays Wiring Fault On Trailer: Notes
Refer to Trailer/Camper Adapter for schematic and connector information.
Normal Operations and Fault Conditions
The braking energy provided to the trailer is modulated with a PWM signal which varies between 0 volt and battery voltage, according to the TBM gain setting, the higher the duty cycle the more braking power available. The TBM varies the PWM signal based on various inputs such as vehicle speed, the brake torque message, BPP switch input, the manual slider switch and the gain buttons. With the vehicle stationary and with the manual slider switch fully to the left with a gain of 10, there should be more than 11 volts supplied to the trailer tow connector. Without a trailer connected, the TBM sends a voltage pulse to the trailer tow connector every 4 seconds as a trailer connectivity test.
When a circuit fault is detected, the TBM sends a message to the IPC to display TRAILER WIRING FAULT, sound an audible alert chime and the TBM disables trailer brake output (except for the trailer connectivity test pulse).
When a trailer is connected to the vehicle the message center should display TRAILER CONNECTED. If the TRAILER WIRING FAULT message is only displayed when the trailer is connected the fault is with the trailer wiring.
The trailer brake system only works with electric-magnet actuated drum type brakes and electric over hydraulic brakes. If the trailer is equipped with a different style of brakes or if the trailer is not equipped with brakes, the system does not function.
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| B148A:11 | Trailer Brake Output: Circuit Short to Ground | This DTC sets in continuous memory when the ignition is set to ON or during the on-demand self test if the current draw on the PWM output circuit is greater than 27 amps. |
| B148A:12 | Trailer Brake Output: Circuit Short to Battery | This DTC sets in continuous memory when the ignition is set to ON and vehicle speed is greater than 3 km/h (2 mph) or during the on-demand self test if the PWM output is greater than 7.1 volts when not braking or greater than 8 volts during braking. |
Possible Sources
- Wiring, terminals or connectors
- TBM
- Trailer