TT.Mk1 Haldex Troubleshooting

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Back to 2000-2005 (Mk1)

Submitted by: TTSchwing
Entered by: MCPaudiTT

Haldex diagnostics and function testing....

First run a VAG-COM diagnostic on the AWD system. A bad controller or connection issue will likely show up here.

Mechanical Function-test of the Haldex coupling.

- Rollout in circle

Aim: Check the function of the coupling and the response on the car. Is to be done on level ground.

1. Drive in circle with minimum turning radius at a speed of about 10 km/h. Disengage the clutch and close the throttle. Let the car roll to full stop.

2. Drive in circle with minimum turning radius at same speed as in case 1. Disengage the clutch and run up the engine to 3000 - 4000 rpm. Let the car roll to full stop.

• If the coupling is working the car will stop in about half the distance in case 2 compared with case 1.

• If there is no difference in the two cases there is a malfunction of the coupling. The problem could be caused by the coupling or by missing signals from the car. A further inspection has to be done to be able to determine the cause of the malfunction.

• If a noise from the HLSC is noticed when turning or driving in circles the oil in the coupling is damaged. The damage can be caused by overheating or by water in the oil.

- AWD test on car lift. (all wheels free to turn.)

Aim: Check the function and the control of the coupling.

1. Pull the handbrake. Disengage the clutch. Start the engine. Put the gearbox in 2:nd gear. Let the engine idle. Engage the clutch.

• Engine is supposed to stop when the clutch is engaged. (HLSC controlled as in handbrake start.) If engine do not stop, disengage the hand brake immediately. Otherwise there is a risk of seriously damage on the HLSC.

2. Disengage the handbrake. Disengage the clutch and start the engine Put the gearbox in 2:nd gear. Let the engine idle. Engage the clutch. At least one front wheel and one rear wheel is supposed to turn. Pull the handbrake for 2 seconds.

• Front wheel is supposed to turn while the rear wheels are supposed to stop when the brake is pulled. Engine is supposed to run all the time. (HLSC controlled as in handbrake turn.) Don't exceed the 2 seconds or repeat the test for more than 5 times during a 5-minute period. Otherwise there is a risk of seriously damage on the HLSC.

Trouble shooting on HLSC

- Visual inspection

Aim: Check for leakage and external damage that affects the function on the HLSC. Is to be done with the car on a car lift.

1. Check for oil-leakage from the coupling. If leakage is found, check oil level at the level screw on the left side of the coupling.

2. Check wires and connecting sockets.

T8 - Socket between car and control unit T8/1, Red = Ign. T8/2, Black = Gnd. T8/3, White = BLS T8/4, Blue = HBLS T8/5, Brown = K-line T8/7, Blue/Grey = CAN low T8/8, Blue/Orange = CAN high

T2 - Socket between control unit and feeder pump T2/1, Yellow = Pump 1 T2/2, Yellow/Black = Pump 2

- Signals

Aim: The following signals from the car affect the function of the HLSC. If one or more of the signals is missing or false the function of the HLSC will be reduced.

Bremse 1; BLS, BTS, ABS Bremse 3; VR, VL, HR, HL

Back to 2000-2005 (Mk1)