- Joined
- Sep 14, 2008
- Messages
- 24,836
- Reaction score
- 6,078
- Points
- 113
- Location
- Wibbleton
- Website
- www.tuffty.co.uk
Haldex system confusion
- Thread starter S3LOUD
- Start date
sorry, but I cant see it. It talks a lot about the haldex and it's electrical parts...and how it couples to the diff. But in the case above the diff only was replaced not the haldex.
Thegoal sorry for any confusion, but most rear diffs for sale will also include the haldex unit (not the ecu) as did mine. I think when ppl talk about replacing the rear diff, they are generally talking about replacing the haldex as you rarely find just the haldex for sale.
Gen 2 will not fit on the 8L vorshsprungdork.
Gen 2 will not fit on the 8L vorshsprungdork.
Ah, I see now. Did it also come with a pre charge pump or did u put your existing on on that too ?
jimbob442
Registered User
eznow - Mine is the exact same with the pump on vagcom showing hi all the time! Had any joy since you posted this?
Cheers buddy
Chaps - it looks like my joy was short lived. I thought my problem was sorted, but it's back (or may not have gone in the first instance!). I went to get my rear diff oil and haldex oil / filter changed on Tuesday and then put fuse 31 back in, but the dragging is still there, but weirdly, just not as noticeable as before
I'm now pretty sure my controller is goosed and the regulator is staying closed so there is maximum pressure on the clutch.
I've ordered a replacement controller off ebay which should be arriving tomorrow so will provide an update then.
Fun and games
The controller is another part you've replaced previously.
So I guess this is number 2 or is it the third one ?
Also I thought you actually bought one of your previous controller off a member from this forum !
So I guess this is number 2 or is it the third one ?
Also I thought you actually bought one of your previous controller off a member from this forum !
- Joined
- Nov 11, 2009
- Messages
- 10,099
- Reaction score
- 739
- Points
- 38
- Location
- west yorks
- Website
- www.stainless-engineering.co.uk
Im not sure how many he bought, but one was from me, a low miler, im not sure what you are trying to say here,,,?
Not replaced the controller before! Replaced the pump with one from s3dave as said above, but that is fully functioning! Waiting for the Royal Mail with baited breath!
S3 Dave, Sorry mate, 'I thought' wrongly as Erf has pointed out.
Erf, well that really narrows it down if you get it working replacing the controller.
Are you able to check what jimbob442 asked above. ?
New controller just arrived in the post and despite be assured it's off a facelift model, it looks like it's the wrong part!
Anyone with a known working hadlex controller off a car with ESP, PLEASE PM ASAP!!!!!!
Anyone with a known working hadlex controller off a car with ESP, PLEASE PM ASAP!!!!!!
Hey folks,
Mine is doing the same thing!! (2001 Audi TT) I have been everyplace asking, I have seen this problem quite a bunch but NEVER any answer! Anybody ever fix this problem? Issue is as follows, car is locked up in 4x4, binding, popping when turning, unplugging the Haldex controler makes it all go away. Vag-Com says pre-charge pump is staying in HI all the time, parking brake will not shut pump off. rear end has been swapped with a known good one, along with pump, controlers have been changed...with new....twice. problem still persists! Did everybody just give up and sell the cars?
I fixed mine eventually by replacing the controller but not until I'd replaced the diff twice, pre charge pump twice, front wheel speed sensors and numerous oil and filter changes! When replacing with second hand parts, there's no way of the knowing the replacement parts are defective too. This has been a very costly exercise for me!
Sorry guys bringing up an old thread, anyone ever diagnose the root cause for this? Having the exact same problem on my pre face lift and don't want to go start replacing parts that are not needed. Also getting no fault codes. Surely someone has a better understanding after 10 years
What exactly is your problem?
Replacing the Haldex controller for a known working replacement cured my issue.
I had a fault with my Haldex system where it was engaging permanent 4WD (max clamping pressure on the clutch pack within the diff), which results in crap economy, and bunny hopping / scraping / dragging the inside rear wheels during tight turns. All garages I took it to were at a loss.
Try pulling fuse 31. That disables the Haldex so by doing that your car will operate in front wheel drive. If that occurs, then you know that your diff and clutch is working fine because you’ve changed from 4WD to 2WD. So based on that, I assumed I had an electrical fault rather than a mechanical fault with the clutch pack. So I changed the wiring harness from diff to Haldex (no change with fault) so then I changed the Haldex controller for a known working used part and that fixed the quattro system so now it engages and disengages at the right times and works perfectly. VCDS wasn’t really useful in diagnosing the fault, but I could hear the pump whirring during output tests so I assumed that was still good. I have since replaced the pump as a preventative measure but it was totally not part of the fault in my instance.
Haldex controllers for gen1 (mk1 A3Q and S3) can no longer be bought brand new and nobody refurbishes them. It’s either too difficult or not worth doing. I’ve spoken to several experts about it. Your best bet is to buy a known working controller IF you suspect it’s the cause of your fault.
Sorry if I’ve repeated loads of stuff already mentioned in the thread but just posting my experience and what I did to cure the problem.
Replacing the Haldex controller for a known working replacement cured my issue.
I had a fault with my Haldex system where it was engaging permanent 4WD (max clamping pressure on the clutch pack within the diff), which results in crap economy, and bunny hopping / scraping / dragging the inside rear wheels during tight turns. All garages I took it to were at a loss.
Try pulling fuse 31. That disables the Haldex so by doing that your car will operate in front wheel drive. If that occurs, then you know that your diff and clutch is working fine because you’ve changed from 4WD to 2WD. So based on that, I assumed I had an electrical fault rather than a mechanical fault with the clutch pack. So I changed the wiring harness from diff to Haldex (no change with fault) so then I changed the Haldex controller for a known working used part and that fixed the quattro system so now it engages and disengages at the right times and works perfectly. VCDS wasn’t really useful in diagnosing the fault, but I could hear the pump whirring during output tests so I assumed that was still good. I have since replaced the pump as a preventative measure but it was totally not part of the fault in my instance.
Haldex controllers for gen1 (mk1 A3Q and S3) can no longer be bought brand new and nobody refurbishes them. It’s either too difficult or not worth doing. I’ve spoken to several experts about it. Your best bet is to buy a known working controller IF you suspect it’s the cause of your fault.
Sorry if I’ve repeated loads of stuff already mentioned in the thread but just posting my experience and what I did to cure the problem.
Last edited:
hi Mad_Dude,
sorry for the late reply was doing a bit more testing as i have only just got a fully licenced VCDS still learning how to use it. Having the same problems as you described. unplugging the haldex makes the problem go away, do not have fust 31 as pre face lift. my pump is whirring on output tests.
have had 2 intermittent faults:
00526 - brake light switch.
01324 - control module for all wheel drive no communication.
also cleared faults that have not come back:
01312 powertrain data bus faulty.
01316 - intermittent.
01314 - intermittent.
I'm thinking it could be something to do with the ABS module as went into measuring blocks to check the steering, lateral & longitudinal sensors and got error messages (not available).
also when checking CAN Gateway was stating No communication. not sure what this does or if it will have an impact on the 4 wheel drive or even if my car has it.
haldex pump is always showing to be on when engine is running.
have installed a brand new pump & swapped the controller for a supposed working unit. don't want to be changing parts willy nilly if I don't have too.
also when running the output test in ABS I get an error function not available message on the very last part of the test. just after ''EDL/EDS Valves / hydrolic Pump =vbatt, front wheels locked''
hope I'm making sense fell like I'm waffling a bit.
Oooh well you need a working brake light switch first of all, so get that replaced/fixed. When the brake switch signal is implausible or hand brake light is on, the Haldex won’t work in 4WD mode. I know your problem is the opposite but to have a fully working quattro system you need that brake pedal switch working. Pulling the fuse suggests that there is nothing mechanically wrong with the diff or clutch pack so then I would replace the Haldex controller. You have a code for “no communication” - so I’d try that next. Sounds like the Haldex clutch pump is working so that’s good. I changed my Haldex controller for an eBay “working one” and what a surprise, it was goosed too. So I bought a proper known working controller from Van Der Veer engineering online from the Netherlands (he bench tests them, cleans them, and then sells them on).
Clear those errors you have and rescan after a drive. If the ‘no communication’ message shows regarding your Haldex controller I’d be inclined to say your second controller is also no good (unless that code appeared when you pulled the Haldex fuse).
Yep, the haldex is well known and documented problem on our cars. I am not surprised you happen to to get a 2nd hand one also with the same issue. I knew there would be a high probability of this hence it took me years before I managed to find one (new) on ebay from the US at a cost of second hand one in the UK - this was years ago too. I didnt want to pay the £900 cost from Audi for a new one (at the time!). I simply drove carefully to limit the probelm whilst looking to get another, plus the fact the milege I did was very low.
As you can read in the above thread back 10 years ago I was asking many questions about the haldex trying to get to the bottom of it. Me and my car is still here
Not had any issues in the last approx 10 years since changing the haldex controller only.Brought a known working rear diff with a controller and now everything is working as it should. Just need to change all the fluids and filter for good measures. Thank you for taking the time to reply to an old thread.
