Removing and installing trailer detector control unit J345 — VW

Removing and installing
trailer detector control unit
J345
Special tools and workshop equipment required
Torque wrench
V.A.G 1783
Coding trailer detector control unit:
Anchor
The
trailer detector control unit
J345
is located behind the left side panel trim in the luggage compartment.
Note
Additional information:
Current flow diagrams, Electrical fault finding and Fitting locations
,
Operating instructions
General description:
The
trailer detector control unit
J345
detects the
“trailer mode”
as of a power decrease of at least 5 W
Remark
, and transmits the corresponding data to various control units via the CAN bus.
“Trailer operation”
can only be detected if at least turn signal indicators or side marker lights are switched on.
Fault detection and fault display:
Note
Use
socket tester
V.A.G 1537/A
to check the control unit.
The
trailer detector control unit
J345
features self-diagnosis to facilitate fault finding.
For fault finding, use the systems described in chapter
“Vehicle diagnosis, testing and information system”
in
“Guided Fault Finding”
mode
Chapter
.
Note
The
trailer detector control unit
J345
is secured in place in different ways, depending on the vehicle's equipment.
In vehicles with battery in luggage compartment, the control unit is attached to the bracket of the main fuse box and secured with a bolt.
In vehicles with battery in engine compartment, the control unit is directly fastened to the body with two bolts.
Removing:
Switch off ignition and all electrical consumers.
Disengage ignition key out in position 0 (forward notch).
Remove left luggage compartment trim
General body repairs, interior
Rep. gr.
70
Luggage compartment trims; Removing and installing side panel trims for luggage compartment
.
Vehicles with battery in engine compartment:
Release and detach all connectors
2
.
Remove both securing bolts
1
.
Remove
trailer detector control unit
J345
3
from vehicle.
Vehicles with battery in luggage compartment:
Release and detach all connectors
3
.
Undo bolt
1
, pull
trailer detector control unit
J345
2
on right out of holder and remove.
Installing:
Installation is carried out in the reverse order. When installing observe the following:
Vehicles with battery in luggage compartment:
During installation, first insert
trailer detector control unit
J345
into holder on right-hand side and then screw it in place on the left-hand side.
Continuation for all vehicles:
Tighten securing bolts to 5 Nm.
Note
Following installation, a new
trailer detector control unit
J345
must be encoded
Anchor
.
Coding trailer detector control unit
Vehicle diagnostic tester
.