Installing mechatronic unit for dual clutch gearbox J743 — VW

🧭 Before you start

Fits: platform codes AV2, AV3, AY3

Don't miss

• »Neutral, neutral, neutral«, or gearbox will not function!
• Handle with care. When levering the plungers out of the mechatronic unit, make sure that you do not brace yourself on the sensors. — Please clean sealing surface of mechatronic unit.
• Look at gearbox input speed sender 3G641. Clip must not be damaged.
• When gripping and putting on, make sure selector forks are not inadvertently pressed out of their position.
• Make sure that plungers meet up correctly in cups of engaging levers.

🔩 Torque settings

Values can differ between engine variants — check the code stamped on your block.

ℹ️ Always cross-check the exact figure against your vehicle's factory manual before final tightening — a wrong torque can damage the engine. These values are extracted from workshop data and may not cover every variant or revision.

📋 Procedure

1. Therefore, check each of 4 selector forks by hand.
2. Also, move each fork into each position in succession. Then disengage all gears and return selector forks to middle position »neutral«. [Note: »Neutral, neutral, neutral«, or gearbox will not function!]
3. Please clean sealing surface where mechatronic unit will make contact later on.
4. Screw in guide pin T10406 hand-tight.
5. ⚠ Handle with care. When levering the plungers out of the mechatronic unit, make sure that you do not brace yourself on the sensors. — Please clean sealing surface of mechatronic unit.

6. Watch out for seal on mechatronic unit.
7. Look at gearbox input speed sender 3G641. Clip must not be damaged.
8. Put on mechatronic unit.
9. When gripping and putting on, make sure selector forks are not inadvertently pressed out of their position.
10. Also observe engaging levers and plungers on mechatronic unit.
11. Screw in 7 new bolts and tighten until finger-tight.
12. Remove guide pins T10406 again.
13. Make sure that plungers meet up correctly in cups of engaging levers.
14. Pull out plungers by hand until they are seated in cups.
15. Now check seat of plungers again.
16. Tighten mechatronic unit diagonally to 10 Nm. — 10 Nm (7.4 lb-ft)
17. Turn assembly lever T10407 clockwise and remove it.
18. Install gearbox input speed sender 3G641.
19. Look at sender. Clip must not be damaged.
20. Remove plug and put breather cap (arrow) in place.
21. ⚠ Risk of damaging gearbox components.Do not under any circumstances touch the contacts in the gearbox connector by hand. Static discharge could destroy the control unit and, consequently, the mechatronic unit. — To become electrostatically discharged, touch an earthed object by hand (without gloves) .
22. Fit connector of mechatronic unit and lock.
23. Attach all retainers and brackets to front of gearbox.
24. Install starter Electrical system27Starter; Removing and installing starter.
25. Fit charge air or coolant hoses if these were removed.
26. Install battery and battery tray Electrical system27Battery; Removing and installing battery.
27. Install air filter housing:
28. If necessary, top up coolant 19Parts of cooling system.
29. Install noise insulation General body repairs, exterior50Noise insulation; Assembly overview - noise insulation.
30. Connect and perform basic measurement.
31. Place plug on »removed« mechatronic unit if necessary.

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