Audi Workshop Service and Repair Manuals

Removing and installing mechatronic unit for dual clutch gearbox -J743- Special tools and workshop equipment required

t  Used oil collection and extraction unit -V.A.G 1782- Removing l  Gearbox in vehicle   Caution Risk of damage to gearbox The engine must not be started when there is no more ATF in the gearbox and the mechatronic unit for dual clutch gearbox -J743- has been removed.   Note t  → Chapter „Repair instructions“. t  → Chapter „Rules for cleanliness when working on the dual clutch gearbox“. t  Notes on dual clutch gearbox 0B5 → Chapter. –  Shift selector lever into position „P“. –  Switch off ignition and take out ignition key.

Caution The gearbox control unit (mechatronic unit) can be damaged by electrostatic discharge. t  Before handling the electrical connector, the mechanic must discharge static by briefly touching an earthed metal object, such as vehicle earth, lifting platform or heater radiator, etc. t  Do not touch contact pins in gearbox connector with bare hands. –  Turn fastener anti-clockwise -arrow- and unplug electrical connector on gearbox.

–  Remove bolt -1-. –  Turn connector housing -2- anti-clockwise -arrow- and detach.

–  Remove bolts -arrows- and pull connecting piece for ATF lines out slightly.   Note Illustration shows connecting piece with ATF lines removed. –  Remove ATF oil pan → Chapter.

–  Place used oil collection and extraction unit -V.A.G 1782- below gearbox. –  Carefully pull ATF filter off mechatronic unit towards rear in direction of -arrow-.

Caution The gearbox control unit (mechatronic unit) can be damaged by electrostatic discharge. t  Before handling the electrical connector, the mechanic must discharge static by briefly touching an earthed metal object, such as vehicle earth, lifting platform or heater radiator, etc. t  Do not touch contact pins in gearbox connector with bare hands. –  Unplug electrical connector (to do so, pull retainer -arrow 1- and press down release catch -arrow 2-).

–  Remove bolts -1 … 6-.   Caution Risk of damage to mechatronic unit. t  Loosen only the bolts marked -1 ... 6-. t  If other bolts are loosened, this may affect the operation of the mechatronic unit or the mechatronic unit could come apart.   Note t  Ensure that the sealing surface is not damaged. t  The mechatronic unit may be tightly seated. t  If it is necessary to lever off the mechatronic unit, get help from a second person to ensure that the mechatronic unit does not drop out. Alternatively, screw bolts -1- and -2- in again slightly to catch mechatronic unit when levering it out. –  Detach mechatronic unit.   Caution Risk of damage to senders on rear side of mechatronic unit. When setting down the mechatronic unit, the side with the bolt heads must be facing downwards.

Installing l  Tightening torques → Chapter „Exploded view - mechatronic unit for dual clutch gearbox -J743-“   Note t  Renew O-rings and bolts for mechatronic unit. t  Do not bend retainer for ATF pipes. –  Remove bolt -arrow-. –  Detach ATF pipes -1- and -2-. –  Detach ATF pipes -3 … 5-. –  Renew O-rings and re-install ATF pipes. –  Tighten bolt -arrow-.   Note Make sure that all selector forks and gear actuators are in »centre position« before installing mechatronic unit for dual clutch gearbox -J743-.

Adjusting selector forks: –  First check each of the selector forks -1 … 4- by hand. Each selector fork has 3 positions: t  Gear engaged -G- t  Neutral -N- (centre position) t  Gear engaged -G- –  Move the 4 selector forks once into each position -arrows-, one after the other. –  Then shift all selector forks back into »centre position«-N-.

Adjusting gear actuators:   Caution The gearbox control unit (mechatronic unit) can be damaged by electrostatic discharge. t  Before handling the electrical connector, the mechanic must discharge static by briefly touching an earthed metal object, such as vehicle earth, lifting platform or heater radiator, etc. t  Do not touch contact pins in gearbox connector with bare hands. t  Do not apply any pressure to the sensors when levering out the plungers. The gear actuators have to be adjusted differently according to the production date of the mechatronic unit. The production date can only be read off from the identification on the mechatronic unit -arrow-. The identification on the mechatronic unit comprises the following information:

Identification of mechatronic unit				Explanation: in this example „L31B1138“
L	31	B1	138
L				Year of manufacture: L = 2010 K = 2009 J = 2008 ... etc.
	31			Calendar week of year of manufacture
		B1		Manufacturer's code for day and shift no. Monday:  shift 1 = A1, shift 2 = B1, shift 3 = C1 Tuesday: shift 1 = D1, shift 2 = E1, shift 3 = F1 Wednesday: shift 1 = G1, shift 2 = H1, shift 3 = I1 ... etc.
			138	Serial number of unit per shift and day, in this case the 138th mechatronic unit in shift B1

From serial number „L31B1138“ onwards, the gear actuators in the mechatronic unit must be adjusted to a different value.   Note t  A mechatronic unit with the identification e.g. „L31A1140“ was manufactured before a unit with the identification „L31B1138“ since it was made in the 1st shift (A1) on Monday. t  Similarly, a mechatronic unit with the identification „L31C1009“ was manufactured after a unit with the identification „L31B1138“ since it was made in the 3rd shift (C1) on Monday.

–  Adjust the four gear actuators on rear side of mechatronic unit to dimension -a- (in »centre position«) by carefully pulling or pushing each gear actuator outwards or inwards. Mechatronic units with identification up to „L31B1137“: l  Dimension -a- = 28 mm Mechatronic units with identification from „L31B1138“ onwards: l  Dimension -a- = 32 mm

–  Align coupling lugs -arrows- of gear actuators so that they engage in eyes of selector forks when installing.

–  Insert mechatronic unit into gearbox housing. l  Dowel pins of mechatronic unit should fit easily into holes on gearbox. l  If mechatronic unit cannot be installed easily, a selector fork or gear actuator may be out of centre position. Check centre positions and re-adjust if necessary.

After inserting mechatronic unit: –  Check all gear actuators through opening between mechatronic unit and gearbox housing using an electric hand torch or similar. l  All four coupling lugs of gear actuators must engage in corresponding eyes of selector forks. –  Tighten bolts for mechatronic unit → Fig.. Further assembly is carried out in reverse sequence; note the following:   Caution The gearbox control unit (mechatronic unit) can be damaged by electrostatic discharge. t  Before handling the electrical connector, the mechanic must discharge static by briefly touching an earthed metal object, such as vehicle earth, lifting platform or heater radiator, etc. t  Do not touch contact pins in gearbox connector with bare hands. –  Make sure that electrical connector on mechatronic unit is properly engaged and secured. –  Observe measures required after connecting battery → Electrical system; Rep. gr.27. –  Install ATF filter → Chapter. –  Install ATF oil pan → Chapter. –  Fill up with ATF → Chapter. l  After renewing mechatronic unit for dual clutch gearbox -J743-, run appropriate „Guided Function“ on vehicle diagnostic tester → Chapter