The second generation Haldex All-Wheel Drive Coupling was introduced in 2004 on the early Audi S3 8P, MK2 Audi TT, VW MK5 R32. The AWD system in the GEN 2 was still a reactive setup like the GEN1 but this time VAG managed to improve the system to change the bias from 90/10 to 50/50.

The reaction time of the Haldex Coupling activating went from ½ of a wheel slipping to ¼ of a wheel slipping. The location of the Hydraulic Oil pump was moved to a more convenient location so removing the exhaust and propshaft is not required.

Haldex GEN 1 &2 all-wheel drive system is reactive. The coupling activates after a wheelspin is detected. However, the reaction is very quick and just 1/4 of a wheel turn is needed to engage all-wheel drive. Electronics can lower the oil pressure only (when parking, ABS working, the handbrake is pulled, etc.), but cannot pre-tension the clutch.

Under normal driving conditions (driving at the constant speed, no slippage), the torque distribution is 90/10 front to rear. When the clutch is locked, torque is evenly distributed between the axles (50/50).

These early versions of the Haldex All-Wheel Drive Coupling used the difference in the rotational speed between the front and rear axle, the Haldex will engage the clutchplates to transfer the right amount of torque the rear axle when the front wheel begins to slip.

Haldex coupling to diff 4x Bolts = 49Nm 

Centre Drive Flange Nut (use once) = 210Nm 

Haldex precharge pump 2 x hex bolts = 6Nm 

Haldex oil filling plug = 15Nm 

Diff oil drain plug = 19Nm 

Diff oil fill plug = 19Nm

Oil Capacity / Refill Quantity
850ml / 700ml *1135ml / 950ml

*please note the Transporter T5 has a higher quantity

Using your diagnostic machine, you can check the Temperature of the Oil in the Haldex Coupling:

• Connect Vehicle Diagnostic Testing Machine
• Select – Running gear Group 01; 40…49
• Select – Four-wheel drive with Haldex coupling
• Select – 01 – Self-diagnosis-capable system
• Select – Four-wheel drive Haldex
• Select – Electrical components
• Select – Oil temperature
• The oil temperature must be between 20 and 40 °C before you empty the oil from the Haldex Coupling – Top Tip – the oil will be close to the right temperate if the vehicle has been driven/idling before you start the process

Once you have checked the oil is at the correct temperature with your diagnostic tool, you can now start the process of emptying the oil from the Haldex Coupling.

• Make sure the vehicle is level and safely placed on your ramp
• Remove fill plug (5mm Hex/Allen)

• Check if an excessive amount of oil leaks – sometimes overfilled by other garages
• Place Oil catch under the oil drain plug (8mm Hex/Allen) and remove

• 24mm Socket Crack loose the Filter Housing, once loose use fingers to remove

• Allow the entire contents to empty (Dispose any oil legally and be environmentally friendly)

• Replace Filter – 35nm torque, however as a guide make sure you feel the filter seal and ensure there is no gap with your fingers – Remember to lube the new o-ring with the clean Haldex Oil, ensuring a good seal is made when you replace filter cap
• Replace drain plug and crush washer 30nm
• Use syringe to fill around 650-700ml with High Performance Haldex Oil (PN: G055 175 A2) into the fill hole – make sure the adapted nozzle fits slightly loose so you can see when the fill hole starts to drip

• Once the fill hole starts to drip the coupling is full
• Replace fill plug with new crush washer

P 01155 – Clutch – 003 – Mechanical Failure – Intermittent

Once you have scanned the vehicles AWD for any fault codes you are now able to test if the coupling is engaging when when the vehicle senses the front wheels slip.

To test the function of the GEN 2 Haldex Coupling follow the below instructions:

Testing the physical function of the Haldex will require either a rolling road or brake roller tester.

• With the front wheel on the rollers engage 1^stgear / drive
• Rev the engine in gear until you 1500 rpm
• If the rear axle doe does not engage at this point and try to push the vehicle forwards the Haldex Coupling is defective and further diagnosis will be required

This procedure is a little less involved than replacing the pump on the later generation Gen 1 Haldex Coupling.

• Remove Haldex Controller 4mm HEX/Allen bolts
• Unplug the electrical connectors from the Haldex Controller

• Remove Haldex pump 4mm HEX/Allen bolts
• Twist pump and remove
• Clean out any debris left in the pump housing.
• Prepare new pump to be fitted and Lubricate rubber O rings before installing
• Fit new pump by twisting the pump into place and making the seal for the o ring
• Plug in and feed the wire to Haldex controller back to original positions
• Use diagnostic machine perform a pump relearn.

• Using your diagnostic tool:

  • Select – 22 – AWD
  • Select – Basic Settings – 04
  • Use the drop-down menu and select – MAS02928 – Pump Motor
  • Select – Go
  • Once selected you should be able to hear the pump cycle itself for around 30 seconds to a minute while it relearns its cycles.
  • When the process is completed, you should see a message advising – finished correctly