4 wheel drive problems / advice needed

[monty-bob]

i have a 2001 S3.

after reading loads of posts ive relised that the 4wheel drive system has loads of issues mine being one of them as it turns out.

after following some posts i noticed my earth strap is broken so i fixed this and still no joy. i then checked the plug for corrosion and it looked like new. what i have now spotted under the car is a plug that was disconnected near a blue thing. i plugged it back in and reversed in a straight line and it was fine. 1st turn that i did , it didnt sound to good. its like it was juddering but the wheels moved freely enough for it to drive. so straight lines are fine but any corners it judders.

any advice on what to check or replace next ?

many thanks

steve

 

[vfr800]

Hi,

sounds like you plugged the haldex controller back in.

can we have some pictures ... ? You say a blue thing? Is it a blue haldex controller?

for some reason the haldex is stuck in permanent 4 wheel drive and not disengaging.

could be the haldex controller or perhaps the abs control unit, can't hurt to get the haldex oil and filter changed but I doubt that will fix your problem.

liam

 

[monty-bob]

alright liam.

gonna to get my dinner in a min so will jack the car up again after that.

the blue thing is above the pump i think it is. looks ackward to get to anyway. i thought id plugged the pump back in to be honest. but then again im new to the audis

 

[jezzy]

lucky you blue haldex.
Could be your pre charge pump.
if you have vcds (vag com) see if there any codes and you can cycle your pre charge pump to make sure its working.

 

[monty-bob]

blue one good then?

the rains starting so wont get another look underneath till tomorrow but thinking about it and seeing a pre charge pump on ebay its the same plug, so has to be the pump i plugged back in.

also i would say the oil sump plug on the diff has never been removed , nothing in the history receipts and no signs of damage on the plug itself.

 

[jezzy]

Haldex service sometimes cures your problems.
And yes blue is very good