Volkswagen Workshop Service and Repair Manuals

Removing and installing mechatronic unit for dual clutch gearbox -J743- (gearbox removed) Always make sure that no dirt can enter an »open« gearbox. In particular, dirt entering an »exposed«mechatronic unit for dual clutch gearbox -J743- and/or oil pump can lead to gearbox failure. Please also refer to the notes on the oil filter change regarding »dirty oil« → Chapter. Removing mechatronic unit To gearbox manufacture date „20 September 2004“, gearboxes were constructed with 2 plugs.

–  Remove bolt -A- near pendulum support. A plastic overflow tube (with 8 mm hexagon socket head bolt, torque setting 3 Nm) is located in this hole. Its length determines the oil level in the gearbox. –  Remove this oil pipe. –  Drain oil. Please also refer to the notes on the oil filter change regarding »dirty oil« → Chapter. –  Screw overflow tube back in, torque setting: 3 Nm.

–  Remove filter if necessary. Often, doubts arise as to whether the filter must be renewed or not. The notes on the oil filter change can help you in reaching this decision → Chapter.

–  Insert new filter with shoulder downwards and tighten cover to 20 Nm. –  Following repair work, it is not necessary to change filter again when filling oil.

–  Remove both -covers-. »Small« cover of oil pump and bolts of »large« cover must always be renewed. Likewise, seal of »large« cover must be renewed.

Before touching mechatronic unit, touch an earthed object → Chapter.

–  Release connector -1- of gearbox input speed sender -G182- and oil temperature sender in multi-plate clutch -G509- using release tool -T10465- and pull connector off.

–  First pull line out of lower clip -arrow I-. –  Then remove it from second clip -arrow II- and lay to side. Do not kink line.

–  Remove -securing bolts- diagonally. Start with bolt -1-. All 10 -securing bolts- must be renewed.

–  Remove mechatronic unit for dual clutch gearbox -J743-. When handling mechatronic unit, pay special attention to the »long« sender arm.   Caution Never lift mechatronic unit on »sender arm« or lay it on arm.

If »arm« is damaged, mechatronic unit must be renewed. –  Lay mechatronic unit to side properly.

Laying mechatronic unit to side properly Installing mechatronic unit   Caution Never lift mechatronic unit on »sender arm« or lay it on arm.

If »arm« is damaged, mechatronic unit must be renewed.

–  Before installation of mechatronic unit, make certain that gearbox input speed sender -G182- with oil temperature sender in multi-plate clutch -G509- is installed.

–  Renew both -O-rings- if you reinstall the »old« mechatronic unit. (Of course a »new« mechatronic unit already has »new« seals.) –  Moisten O-rings with dual clutch gearbox oil.

–  Carefully set mechatronic unit on dowel pins -arrow-. Ensure that »sender arm« locates in its -fitting position-. –  Do not pinch wiring. Be very careful: do not pinch wiring!

All 10 -securing bolts- must be renewed. –  First start all -securing bolts-»by hand«. –  Then tighten all 10 -bolts- diagonally to 5 Nm. After this, turn a further 90° in same sequence. Start with bolt -1-.

–  First press wiring for gearbox input speed sender -G182- with oil temperature sender in multi-plate clutch -G509- into clip -II-. Then into clip -I-. –  Press connection onto mechatronic unit. –  Set cover over mechatronic unit, being careful not to pinch any wiring.

–  Insert new bolts -arrows- and tighten diagonally in several stages to 10 Nm.

–  Set new oil pump cover -A- in place and tighten bolts -arrows- diagonally in several stages to 8 Nm. After installing gearbox –  Top up oil, check level and top up → Chapter.

–  Connect → Vehicle diagnostic tester. –  Carry out basic settings.