hi all my 1999 s3 is only 2 wheel drive, I've checked for earth strap broken, but mine is a preface lift and the earth cable is not fitted nor is there a fuse for the haldex, I got a cheap vag-com and got fault code 00526 brake light switch, I cleared the fault and it has not come back, but my car is still 2 wheel drive, would a faulty brake light switch stop my haldex 4 wheel drive working ?, and if the brake light switch is faulty why do my brake lights still work? and why aint the fault come back,. Please help, thanks in advance ..
s3 haldex 4x4 problem help please
- Thread starter HOTTIGGER
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Search previous posts on haldex issues, there is a complete thread on problems and resolutions . However it will have an earth cable and separate fuse somewhere along the line for the haldex controller to work surely......?
Have a good look around on here in previous threads and I'm sure you will find the answer you require my friend.
Cheers , Sean
Have a good look around on here in previous threads and I'm sure you will find the answer you require my friend.
Cheers , Sean
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No Zek, my 99 S3's Haldex is not fused either, has to be disconnected at the diff for a RR run!
Anyways, to answer the op's question, either your Haldex controller is faulty or the wires going to it is corroded.
HI there aint an earth strap on pre facelifts nor fuse, vag com says its a brake light switch.
hi preface lifts dont have an earth strap or fuse, ive read loads of threads m8, im no futher foward , thankds
hi m8 thanks for reaply, yes mine is a 1999 preface life, no earth or fuse,the wires going to it are fine, vag-com got fault code for brake light switch, ive reset and fault has not come back but still 2wheel drive. thanks
Check your controller.. mines pre facelift but has a fuse coz its speshull 
but its your controller that'll be the problem or wires. Is your abs light on? tried cycling the pump also?
but its your controller that'll be the problem or wires. Is your abs light on? tried cycling the pump also?could be either the controller as others have said...or could be the actual haldex clutch which would mean a replacement rear diff...or could be the pre charge pump.
HI GOPS thanks for reapling, you say check the controller, wot do you mean ?, no abs light on in dash and the abs pump hase bin recyled, many thanks
Check your controller.. mines pre facelift but has a fuse coz its speshull
Next on the left side near where the prop meets the diff is the haldex controller which controls the 4wd. That unit might be knackered. Check the wiring, and cycle the haldex pump on vagcom to see if that's working.
HI GOPS, thanks for taking the time to help me, ive only got a cheap ebay vag-com cabel, can i cycle the haldex pump with it ? thanks again..
there is a little shield on the rear diff at the back end, this houses a wiring connector to the haldex.
unbolt the shield and unclip the connector if its corroded inside clean it up.
if its full of oil your pre charge pump is gone.
if you press the brake it disengages your haldex.
so your brake switch sensor could be gone
unbolt the shield and unclip the connector if its corroded inside clean it up.
if its full of oil your pre charge pump is gone.
if you press the brake it disengages your haldex.
so your brake switch sensor could be gone
Hi jezzy thanks for reaply, brake sensor or brake switch ? I got a fault code saying brake light switch. But cleared it and it ain't come back, thanks again.
Yeh sorry mate it's jus I've seen 3 pre facelift with them like GOPs said.
And change brake switch 1st , might be a cheap fix
Cheers, Sean
hi s33nyboy thanks for reaply, brake light switch ? or brake switch? or brake switch sensor like jezzy just said in thread ? i hade a fault code saying brake light switch. thanks again m8.
hi again jezzy, yes code has cleared and not come back, and is defo only 2wheel drive, i checked on the wet slippy roads not long ago, i cleared the fault code took it for a drive and scanned it again, no fault code, i dint change the brake light switch, i just cleared it thinking if it was faulty it wood pop back up as a fault code again, is this the case ? thanks again martin
No 4wd drive and no code.
if your car is not slammed to the ground you will be able to undo the little shield and check the connector on the rear diff without jacking up the rear(the connector is on the rear diff not the haldex)
Dosent take that long to check it and it will give you a better idea of your issue.
Mine was the pump. oil in the connector. others was corroded wires.
sometimes a oil and filter change on your haldex system will bring back 4wd.
i would check the connector first. and keep an eye on your fault codes.
keep us updated
if your car is not slammed to the ground you will be able to undo the little shield and check the connector on the rear diff without jacking up the rear(the connector is on the rear diff not the haldex)
Dosent take that long to check it and it will give you a better idea of your issue.
Mine was the pump. oil in the connector. others was corroded wires.
sometimes a oil and filter change on your haldex system will bring back 4wd.
i would check the connector first. and keep an eye on your fault codes.
keep us updated
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hi jezzy, ive found 1 end of the connector under a heat shield by the back bumper, is that the heat shield i need to remove ? or the heat shield above the rear axel and diff ?, am i right in thinking that the brake light switch is not faulty as the fault code aint come back? or is it still faulty and ive just hide the fault when i cleared it ? , thanks again martin.
The heat shield (more of a brackett than heat shield sorry)is tiny a couple of inches across and is on the rear diff.
When you find the connector it joins the wires together in a block, so when it comes apart, pins one side and holes for the pins on the other.
im not sure on the code (brake) if it does not come back you may you have moved it and is now working?
When you find the connector it joins the wires together in a block, so when it comes apart, pins one side and holes for the pins on the other.
im not sure on the code (brake) if it does not come back you may you have moved it and is now working?
here is the connector in question
http://www.audi-sport.net/vb/a3-s3-...working-no-communication-etc-look-inside.html
http://www.audi-sport.net/vb/a3-s3-...working-no-communication-etc-look-inside.html
Has anyone made any progress here?? I've recently changed my haldex oil and filter again and now the pre charge pump (used unit). Still no FU&KING JOY 
Surely this is an electric fault? Haldex kicks in, but doesn't disengage. Take out the fuse and voila. Haldex disengages.
I still have to get my front right speed sensor as that is throwing an intermittent fault despite me changing it
I've spent so much on getting this car fixed, I just want my haldex to work
Surely this is an electric fault? Haldex kicks in, but doesn't disengage. Take out the fuse and voila. Haldex disengages.
I still have to get my front right speed sensor as that is throwing an intermittent fault despite me changing it
I've spent so much on getting this car fixed, I just want my haldex to work
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Has anyone made any progress here?? I've recently changed my haldex oil and filter again and now the pre charge pump (used unit). Still no FU&KING JOY
Surely this is an electric fault? Haldex kicks in, but doesn't disengage. Take out the fuse and voila. Haldex disengages.
I still have to get my front right speed sensor as that is throwing an intermittent fault despite me changing it
I've spent so much on getting this car fixed, I just want my haldex to work
Sounds like the speed sensor fault might not be helping... if its detecting 'wheelspin' (could be confusing the signal if there is a fault with the sensor or wiring to the sensor) then this could be tricking the haldex into locking on and staying on as it thinks it is in perpetual wheelspin...
I would be looking at sorting the speed sensor fault out first before trying to find the haldex one as the systems are closely linked... you may find fixing the speed sensor issue cures the haldex one..
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