Trailer Lamps - With TRM
System Diagram
Network Message Chart
BCM Network Input Messages
| Broadcast Message | Originating Module | Message Purpose |
|---|---|---|
| Gear position | PCM | Indicates the transmission is in reverse gear to the BCM. When the transmission is in REVERSE and the ignition in RUN, the BCM provides voltage to the reversing lamps. |
| Turn signal switch status | SCCM | Indicates the turn signal stalk position on the LH steering column multifunction switch (left/right lane change or turn signal on or off). |
TRM Network Input Messages
| Broadcast Message | Originating Module | Message Purpose |
|---|---|---|
| Turn indication request | BCM | A command to the TRM to activate/deactivate the turn indicator output to the trailer tow connector. |
| Stoplamp request | BCM | A command to the TRM to activate/deactivate the stop lamps output to the trailer tow connector. |
Trailer Stop-Turn Lamps
The SCCM monitors the LH steering column multifunction switch position. When the LH steering column multifunction switch is in the left or right turn position, the SCCM sends a message over the HS-CAN2 to the GWM then the GWM sends the message to the BCM over the HS-CAN1 indicating a request for the LH or RH turn signal.
When the BCM receives a request for a turn signal, the BCM sends a turn indicator command message over the HS-CAN1 to the GWM, then the GWM sends a turn indicator command message over the HS-CAN3 to the TRM to activate the requested stop/turn indicator output to the trailer tow connector.
When the BCM receives input from the stoplamp switch indicating that the brake pedal is being pressed, the TRM receives a stoplamp activation message over the HS-CAN3 to activate the requested stop/turn indicator output to the trailer tow connector.
Trailer Parking Lamps
The headlamp switch sends a headlamp switch status message over the LIN to the BCM to indicate the headlamp switch status (position or a fault with the headlamp switch).
When the parking lamps or headlamps position is selected, the BCM provides a ground path to the BJB parking lamps trailer tow relay. When the BCM provides ground the parking lamps trailer tow relay, the relay is energized and the relay provides parking lamp voltage to the trailer tow connector.
Trailer Reversing Lamps
When the transmission is in REVERSE, the PCM sends a message over the HS-CAN1 to the BCM indicating the transmission is in REVERSE. The BCM provides voltage to the reversing lamps trailer tow relay (integral to the BJB) when it receives the message that the transmission is in REVERSE and the ignition is in RUN. When the BCM provides voltage to the reversing lamps trailer tow relay, the relay is energized and the relay provides reversing lamp voltage to the trailer tow connector.
Trailer Battery Charging
The TRM provides voltage to the trailer tow connector for trailer battery charging when all the following are true:
- The TRM detects that a trailer is connected.
- The ignition is in ACC or ON.
- The BCM load shed strategy is not active (a message is displayed in the instrument cluster, such as Low Battery Features Temporarily Turned Off or Turn Power Off To Save Battery, to indicate that BCM load shed strategy is active).
Trailer And Lamp Outage Detection
The TRM senses resistance in the LH and RH brake/turn signal output circuits that is within a calibrated range. If the resistance is higher than the calibrated range on either the LH or RH brake/turn signal output circuits, the TRM reports a trailer lamp fault message. If the resistance is lower than the calibrated range on one of the LH or RH brake/turn signal output circuits when the brake is pressed during the ignition cycle, the TRM reports a trailer lamp fault message and the TRM sets a DTC.