Volkswagen Workshop Service and Repair Manuals

Removing and installing mechatronic unit for dual clutch gearbox -J743- (gearbox installed) Removing and installing with gearbox removed is described in → Chapter. Special tools and workshop equipment required

t  Torque wrench -V.A.G 1331-

t  Used oil collection and extraction unit -V.A.G 1782-

t  Adapter for filling oil -VAS 6262 A- Removing mechatronic unit Always make sure that no dirt can enter an »open« gearbox. In particular, dirt entering an »exposed«mechatronic unit for dual clutch gearbox -J743- or oil pump can lead to gearbox failure. Please also refer to the notes on the oil filter change regarding »dirty oil« → Chapter. The mechatronic unit can stick on the dowel pins when the gearbox is very warm. Then let the gearbox cool off. –  Raise vehicle. All 4 supports of the lifting platform are at the same height. –  Move selector lever to position „P“ position. –  Remove noise insulation → General body repairs, exterior; Rep. gr.50. If present:

–  Remove connecting hose between charge air cooler and charge air pipe → Rep. gr.21.   Note It is possible that parts having nothing to do with the mechatronic unit must be removed. This depends on the vehicle's equipment. This will create enough space to remove the mechatronic unit.

t  Depending on the vehicle, these parts may include, for example, t  Radiator fan support t  Additional lines for air conditioner t  Charge air or air cooling pipes t  For example, the left wheel housing liner must be removed from the Scirocco with 2 litre petrol engine.

–  Release mechatronic unit connector -1- by turning and pull off connector.   Note Item -A- can be disregarded.

–  Unbolt wiring retainer from front of »large« gearbox cover (2 nuts M6). Specified torque: 10 Nm –  Raise lines near cover and tie. –  Position used oil collection and extraction unit -V.A.G 1782- under gearbox in area of »large« cover.   Caution Oil runs out of cover when bolts are unscrewed. Danger of injury from hot gear oil.

–  Loosen bolts -arrows- of cover diagonally and remove. Hold cover when doing this. –  Allow oil to drain out and then remove cover with seal. Approximately 3 litres of oil will run out.   Note »Small« cover of oil pump, as well as seal and bolts of »large« cover must always be renewed.

–  Remove oil pump cover -A-.

–  Remove bolts -2, 3- of the pendulum support on gearbox → Rep. gr.40. This allows the gearbox to be »pushed back« a little in order to remove the mechatronic unit.

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

–  Carefully release connector of gearbox input speed sender -G182- with oil temperature sender in multi-plate clutch -G509- using a small screwdriver -1-. –  Only press onto locking mechanism with -1-. –  Do not lever it. Do not use screwdriver as a lever. –  Use -2- to loosen connector. Be very careful. The fastener of the connector can break. If this happens, the sender must be renewed. Do not pull on line! –  Pull off connector.

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

–  Loosen securing bolts -1- through -10- in given order and remove.

–  Carefully pull mechatronic unit out of gearbox housing so that sender arm -B- on back is no longer in gearbox housing. When handling mechatronic unit, pay special attention to the »long« sender arm. –  Carefully swing mechatronic unit for dual clutch gearbox -J743- downwards.

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

If »arm« is damaged, mechatronic unit must be renewed. Installing mechatronic unit Before touching mechatronic unit, touch an earthed object → Chapter.

–  Carefully set mechatronic unit for dual clutch gearbox -J743- in gearbox housing. –  Do not pinch wiring. –  Carefully set mechatronic unit on dowel pins -arrow-. Ensure that »sender arm« locates in its -fitting position-. –  Look to see if mechatronic unit has made contact correctly.

–  Screw in new bolts -1- through -10- hand-tight. –  Tighten bolts in given order to 5 Nm + 90° (1/4 turn). –  Hook line -A- first in upper retaining lug, and then in lower -arrows-. –  Push on connector and engage.

–  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. –  Clean cover seal and sealing surfaces on gearbox. –  Ensure proper seating of seal. –  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. –  Attach wire retainer to cover and tighten nuts to 10 Nm. –  Push on connector for mechatronic unit for dual clutch gearbox -J743- and engage lock by turning. –  If present: install connecting hose between charge air cooler and charge air pipe → Rep. gr.21. –  Reinstall any parts which may have been removed from the vehicle.

–  Do not start engine! –  Please renew filter if oil is contaminated → Chapter. –  Connect → Vehicle diagnostic tester. –  Position used oil collection and extraction unit -V.A.G 1782- under gearbox in area of oil drain plug.

–  Remove oil drain plug close to pendulum support -arrow-.

–  Screw adapter of adapter for filling oil -VAS 6262 A- hand-tight into inspection hole.

–  Shake bottles before opening. –  Fill 3 litres of oil. –  To change bottle, shut off tap or hold adapter for filling oil -VAS 6262 A- higher than gearbox. Then start engine and check and replenish oil. Adapter for filling oil -VAS 6262 A- remains installed initially. –  Checking oil level and topping up → Chapter –  Install noise insulation → General body repairs, exterior; Rep. gr.50. –  Carry out basic settings.