Volkswagen Golf Service & Repair Manual: Trailer detector control unit -J345-

Volkswagen Golf Service & Repair Manual / Guide for using trailers / Technical prerequisites / Trailer detector control unit -J345-

General description:

The trailer detector control unit -J345- detects a power consumption of at least 5 W → Remark when “towing a trailer” and passes this information to various control units via the CAN data bus.

The trailer detector control unit -J345- receives information (regulation of lights) from the onboard supply control unit -J519- and the convenience system central control unit -J393- via the CAN data bus.

¹⁾	The turn signal system or the side lights must be switched on to detect the “trailer”.

Information concerning checking the control unit, fault displays and fault finding is located in the workshop manual → Electrical system; Rep. gr.97.

Retrofitting trailer detector control unit -J345-

Retrofitting a trailer detector control unit -J345- is possible in essence but not easy because it has to be connected to the CAN data bus of the vehicle. The control unit then has to be coded with the aid of “Guided fault finding” → Vehicle diagnostic tester.

Note

It is recommended that alternative control units available on the open market and not approved by Volkswagen are avoided without exception. If equipment of this type is installed, the guarantee will become void. Generally, these are connected to the tail lights and not integrated in the electrical system of the vehicle, which makes far more sense. The consequence is that faulty diagnoses in the bulb failure warning system or malfunctions can occur, among other things. Furthermore, dimmed bulbs (combined brake and tail light) cannot be actuated.

Coding trailer detector control unit -J345-

Coding is described in → Electrical system; Rep. gr.97.

Trailer socket

The trailer socket must be connected in accordance with the manufacturer's instructions to the electrical system of the pulling vehicle. When i ...

Engine cooling

Since higher demands are placed on the engine cooling system when a trailer is being towed, the cooling system is uprated in conjunction with factory fitted towing at ...

Other materials:

Removing and installing air intake silencer
Removing – Switch off electrical consumers. – Switch off auxiliary and supplementary heater and switch off ignition. – Remove front part of front right wheel hou ...

Removing and installing ignition/starter switch
Removing – Remove lower steering column trim → General body repairs, interior; Rep. gr.68. – Disconnect electrical connector -1-. ...

Corrosion protection measures for wing surface in contact with wheel housing liner
Note The corrosion protection measure is to be carried out in the groove of the wing of all new replacement parts which have not had the additional sealant applied at the factory. The additional sealant is intended to prevent the wheel hous ...