a bit more info
TRAILER MODULE
The trailer module is fitted to all vehicles and is located in the RH side of the luggage compartment, behind the removable trim panel, adjacent to the rear auxiliary fusebox. The module is required to separate the load circuits of the trailer from the load circuits of the towing vehicle. This allows separate monitoring of the vehicle lamps and the trailer circuits.
The trailer module comprises a double transistor for reversing lamp and rear fog lamp operation and overload proof MOSFET circuit breakers for the following lamps:
Left turn signal indicator
Right turn signal indicator
Stop lamps
Left tail lamp
Right tail lamp
Permanent trailer battery supply circuits.
The above lamps are connected to the trailer module via direct connections to the applicable lamps. The rear fog lamps and reversing lamps are not directly connected to the lamp units because these lamps must be disabled when the trailer socket is connected.
The LCM communicates with the trailer module via a bi-directional, dedicated serial link. The rear fog lamps and reversing lamps are controlled on this link. The trailer module also uses this link to transmit error messages for the trailer lamps to the LCM.
The trailer module has two modes of operation; sleep mode and normal mode. Sleep mode is initiated by the LCM after a predetermined time. In this mode the trailer module processor clock speed is reduced to a minimum and all loads are switched off to keep current consumption to a minimum. The module operates in normal mode on receipt of an applicable message from the LCM. The required loads and the current supply for bulb failure detection are activated.
The LCM communicates with the trailer module every 2 seconds with a normal mode telegram. If the trailer module no longer responds, the data link to the module is switched low for 1 second after ten unsuccessful attempts to establish the communication. When the LCM switches the data link low, the trailer module is 'reset'. If communication is not established after thirty attempts in succession, the LCM assumes the module is defective and records an applicable error message in the error memory.
If a replacement trailer module is fitted, the LCM instantly recognizes it via the data link. Connection of the Land Rover recommended diagnostic tool is not required to establish communications between the LCM and the trailer module.
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