Tow Hitch System

Courtesy of VOLVO CARS CORPORATION

Trailer module (TRM) (4/110) ensures that the correct type of signal is transmitted to the cable harness for the tow hitch.

Trailer module (TRM) receives messages on the CAN network, from the central electronic module (CEM) (4/56), about when the turn signal lamps, tail lamps, back-up (reversing) lamp and fog lamps must be activated.

The stop lamp signal is directly connected from the central electronic module (CEM) via the rear tail lamp. A stop lamp signal is transmitted from the central electronic module (CEM) to trailer module (TRM) on the CAN network. The trailer module (TRM) transmits the signal on to the cable harness for the tow hitch.

The output signal for charging (+12 V voltage) is activated when the ignition is changed from position 0 to I, II or III. The trailer module (TRM) transmits the signal via an internal relay and an internal fuse.

Trailer module (TRM) transmits messages on the CAN network, to the central electronic module (CEM) and Driver information module (DIM) (5/1), about the status of the trailer stop lamp. If the bulbs for the stop lamps are blown the information lamp lights in the Driver information module (DIM) and a warning message is displayed.

If any trailer is attached to the output for the trailer switch the Trailer module (TRM) transmits a message on the CAN network to:

• central electronic module (CEM)
• driver information module (DIM)
• Differential Electronic Module (DEM) (4/82) (option)
• Parking Assistance Camera (PAC) (4/120) (option)
• Parking Assistance Module (PAM) (4/86) (option).

A special warning lamp in the Driver information module (DIM) will indicate when the turn signal lamps are used when a trailer is connected. If the bulb for a turn signal lamp is blown the special warning lamp will not light. However, a text message is displayed in the Driver information module (DIM).

The output signals for back-up (reverse) lamps, fog lamps and charging (12V supply) in the trailer connector are market dependent. Outputs for trailer connectors are available in several versions with different numbers of terminals.