Removing and installing mechatronic unit for dual clutch gearbox J743 with gearbox installed — AUDI

🧭 Before you start

Fits: Audi A3 (8P, 2003–2012)

• Opens: coolant, engine oil
• Special tools named: T10407

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• Depending on version, different types of noise insulation may be fitted.
• The back of the assembly lever must make contact with the gearbox housing.
• The assembly lever T10407 remains inserted between the engaging levers and the gearbox housing while removing and installing the mechatronic unit.If necessary, press the assembly lever T10407 against the gearbox housing.
• Make sure that the screwdriver used to support the assembly lever T10407 does not jam against the mechatronic unit.
• A new mechatronic unit is supplied with the correct oil filling.

📋 Procedure

1. ⚠ Do not run engine or tow vehicle with mechatronic unit for dual clutch gearbox J743 removed or when there is no gear oil in the gearbox. — Remove noise insulation General body repairs, exterior50. [Note: Depending on version, different types of noise insulation may be fitted.] [Note: The vehicle diagnostic tester moves all gear actuators into "“neutral”" position.In this position, insert assembly lever T10407 between engaging lever and gearbox housing. This makes it possible to remove load from the plungers of the mechatronic unit so that they can be removed by hand from the retainers on the engaging levers.]
2. Shift selector lever into position "“P”".
3. Connect vehicle diagnostic tester and switch on ignition.
4. Select the following menu items:
5. Switch off ignition.

6. ⚠ Never touch the contacts in the gearbox connector with your hands. Static discharge could cause irreparable damage to the control unit and, consequently, the mechatronic unit. — Touch a suitable earthed object with your hand (without gloves) to discharge any static electricity.
7. Release and unplug electrical connector (1) for dual clutch gearbox.
8. Take electrical connector (3) out of bracket.
9. Remove bracket and tie up together with connectors (2) and (3).
10. Remove nuts (arrows) and push bracket (1) to one side.
11. Remove oil drain plug (arrow) from gearbox.
12. Allow oil to drain off, then retighten oil drain plug.
13. Remove cap from breather opening and seal off with a plug from engine bung setVAS 6122 to prevent oil from escaping.
14. Carefully pull gearbox input speed sender G182 out of gearbox. [Note: The following step is necessary in order to lift the two engaging levers of the dual clutch away from the plungers of the mechatronic unit. Otherwise, the levers will jam the mechatronic unit at the plungers so that it cannot be removed.]
15. Insert assembly lever T10407 below plungers (2) between gearbox housing and the two engaging levers (1)(arrow), as shown in illustration.
16. Only slide in assembly lever T10407 until groove on assembly lever is in line with rib on housing (arrows), as shown in illustration. Do not slide it in all the way. [Note: The back of the assembly lever must make contact with the gearbox housing.]
17. Now rotate assembly lever T10407 90° anti-clockwise about its own axis (arrow A) so as to lift engaging levers away from plungers (1)(arrow B).
18. If necessary, press the assembly lever T10407 against the gearbox housing with a screwdriver to prevent it from slipping out when it is turned. [Note: The assembly lever T10407 remains inserted between the engaging levers and the gearbox housing while removing and installing the mechatronic unit.If necessary, press the assembly lever T10407 against the gearbox housing.]
19. ⚠ Risk of irreparable damage to gearbox components.Before touching or removing the mechatronic unit for dual clutch gearbox J743, always discharge any static electricity by touching an earthed object with your hand.Never touch the contacts in the gearbox connector with your hands. Static discharge could cause irreparable damage to the control unit and, consequently, the mechatronic unit. — Touch vehicle earth with your hand (without gloves) to discharge any static electricity. [Note: Make sure that the screwdriver used to support the assembly lever T10407 does not jam against the mechatronic unit.] [Note: The mechatronic unit is returned for reconditioning complete with oil filling.]
20. ⚠ Risk of damage to mechatronic unit for dual clutch gearbox J743!Do not loosen bolts securing cover on mechatronic unit for dual clutch gearbox J743.Make sure that no oil escapes through the breather hole when placing down mechatronic unit for dual clutch gearbox J743 after removal.Oil that has escaped cannot be refilled! — Remove bolts (B) in diagonal sequence.
21. Remove bolts (A) in diagonal sequence.
22. Detach mechatronic unit from gearbox. [Note: A new mechatronic unit is supplied with the correct oil filling.]
23. ⚠ Risk of damage to mechatronic unit for dual clutch gearbox J743.In some cases it may not be possible to remove the mechatronic unit.This can happen if the gear actuator at the top left of the mechatronic unit is stuck.Do not attempt to remove the mechatronic unit by force.The mechatronic unit must be first brought into the correct position for removal by hand . — Seal off breather opening of mechatronic unit with a cap from engine bung setVAS 6122 to prevent oil from escaping. [Note: Make sure that all selector forks are in "“centre position”" before installing mechatronic unit for dual clutch gearbox J743. "“Centre position”" is position (N) (neutral) in the illustration below.No gear is engaged in this position, the gearbox is in neutral.]
24. First check each of the 4 selector forks by hand.
25. Move the 4 selector forks once into each position (arrows), one after the other.
26. Then shift all selector forks back into »centre position«, position (N). [Note: Turn one of the wheels slightly to make it easier to move the selector forks.]
27. Clean sealing surface on which mechatronic unit is to be installed.
28. Screw in bolt guide pins T10406 hand-tight.
29. ⚠ Risk of damage to mechatronic unit for dual clutch gearbox J743.Do not apply any pressure to the sensors when levering out the plungers. — Adjust the four gear actuators on the reverse side of mechatronic unit for dual clutch gearbox J743 to the specified positions.
30. Clean sealing surface on mechatronic unit.
31. Put on mechatronic unit.
32. Tighten bolts for mechatronic unit .
33. ⚠ The clutches can be damaged.If the clutch engaging levers contact the clutch actuators of the mechatronic unit abruptly, this can move the actuators out of position and activate the clutch self-adjustment. The status prior to self-adjustment cannot be recovered. — Turn assembly lever T10407 slowly and carefully in clockwise direction and remove.
34. Pull out plungers by hand until they are seated correctly in retainers.
35. Install gearbox input speed sender G182 in opposite direction of (arrow).
36. Fit cover.
37. Remove sealing plug from breather opening of mechatronic unit and fit breather cap (arrow). [Note: If the mechatronic unit is being renewed, fit the sealing plug on the old mechatronic unit so it remains oil-tight when it is returned for reconditioning.Do not drain oil out of the old mechatronic unit.]
38. ⚠ Risk of damage to gearbox components.Never touch the contacts in the gearbox connector with your hands. Static discharge could cause irreparable damage to the control unit and, consequently, the mechatronic unit. — Touch a suitable earthed object with your hand (without gloves) to discharge any static electricity.
39. Attach electrical connector (1) for dual clutch gearbox and lock.
40. Install bracket with connectors (2) and (3).
41. Fill up gear oil .
42. Observe measures which have to be taken after connecting the battery Electrical system27.
43. Fill cooling system Engine, mechanics19.
44. Check adjustment of selector lever cable and adjust if necessary .
45. After installing the gearbox, run the Basic setting complete function in Guided Functions.

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