Haldex Control Unit Fluke?
 

I just bought a 2001 Audi TT 225 hp awd 6-speed. I was on my way home from picking it up and I stalled the cargoing into 1st and after that my check engine light comes on. So I took to a certified audi dealership and they told me it's the haldex control unit and it's going to cost me $1500 to fix. Now the guy told me the computers in these cars check for problems right when they start and that if any problems show up that light will turn back on after a cycle of driving. Well I've drove it for a day or so now and that light hasn't come back on. One of the mechanics there said he has never seen the haldex control unit go out on the 1.8L ever. I'm just trying to get some info to see if anyone else has had this problem and what I should do. Thanks

RE: Haldex Control Unit Fluke?
 

I have a 2001 225 quattro and my haldex went out when I first got it too. I got mine in 2003 with low mileage and it was covered under the warranty still. I think they changed it during my 40,000 mile service

RE: Haldex Control Unit Fluke?
 

How did you know it went out, did you notice the rear wheels were pushin as hard or something or did they just tell you that it went out and you just said eh ok fix it since you had the warrenty.I don't have the warrenty so I really don't wanna blow a bunch of money if it's not really broke.

RE: Haldex Control Unit Fluke?
 

I had just bought the car and it was probably already out when I bought it. since I had just got it... I didn't even know it was bad. The dealer told me it was bad after they replaced it for free during the service.

RE: Haldex Control Unit Fluke?
 

my 01 225 TT's haldex unit was bad when I bought it but it was not the CEL that was on but the ESP light. If you have VAGCOM (even shareware version) and the cable, you can check to see.

RE: Haldex Control Unit Fluke?
 

Man, 01 225 Haldexes friggin blow.

RE: Haldex Control Unit Fluke?
 

Darkcolla... if your Haldex is bad don't put the stock one back in. Get one of the blue units. Here's a link to HPA Motorsports's Haldex Page. The blue unit is an improvement over the stock one and it's $899 vs the $1500 for the stock unit.

http://www.hpamotorsports.com/produc...ain_haldex.htm

RE: Haldex Control Unit Fluke?
 

I say wait for another CEL and take it to Auto Zone to have them scan it. Look up the code and see what's really going on. I doubt it's your Haldex though. If you feel so inclined change the haldex fluid and filter. It should be done every 20K reguardless. Since Audi doesn't make it manditory they donot included in their regular service.

Heh or if you would like... try to recreate the problem. Just for $hits and giggles ya know. Stall it again in first see if you get another CEL...
I wouldn't recommend doing this repeatedly! Just once will suffice.

RE: Haldex Control Unit Fluke?
 

Do what applies (roll out test, and jackstand/lift test)

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

RE: Haldex Control Unit Fluke?
 

Thanks for all the info, I'm gonna take it to an autozone and see if they can scan it to see what they think it is...For the past 3 days now the light keeps going on and off. Either it's supposed to do that orthere is something wrong with the code?