Strange haldex issue. prob disappears once warm?

[Paul_TDi]

Bought my car at christmas when the haldex controller was poop and the car crabbed at slow speeds on corners. the controller was replaced under garage warranty for a 2nd hand part with very low miles along with a oil and filter change.

It's been running great until recently, my MAF went down which is now sorted but for the past couple of weeks since the MAF was down the ESP light has been coming on now and again. It's been scanned and it's saying no contact with haldex ecu or something to that effect.

But here's the twist, start from cold the light is on, I can restart as much as I want and it wont go, but if I restart once up to 90 degrees then the light goes off and I have 4wd back.

I thought it was a wiring issue since it was on and off, but what with the temp issue I don't know?

EDIT- Should of mentioned, car in question is a '02 A3 1.9 TDI Quattro Sport.

 

[<tuffty/>]

Checked the wiring plug and earth strap?

<tuffty/>

 

[Paul_TDi]

I know the earthing strap is knackered, has been since I bought it.

Not had a chance to check the plug yet though. I thought it was wiring at first but then thought it might be more sinister with it relating to heat?

 

[<tuffty/>]

There is a temp sensor in the controller so the controller knows to disable the haldex clutch if the hydraulic fluid is too hot... if the plug is corroded its plausible heat could affect its connectivity but its gotta be worth a look regardless... I'd fit a new earth strap too so you can eliminate that as an issue

<tuffty/>

 

[Paul_TDi]

Ah right, I'll try and get under the car to have a nosey at the weekend.

Cheers.

 

[<tuffty/>]

From the stickies...

http://www.audi-sport.net/vb/a3-s3-...working-no-communication-etc-look-inside.html

<tuffty/>

 

[Paul_TDi]

Cheers for the link, I've read that stickie a few times before on my initial issues.

Checked the plug and thats fine, as said the earth strap is missing and find it hard to believe thats causing an issue now, as I know it's been hanging on by 1 end since I first looked under the car when I got it.

Regardless I'm getting under the car again tomorrow and will replace it then see what happens.

The restarting the car once warm isn't a dead-cert fix anymore either now. Pain in the **** this as looking to sell. Need an estate!

 

[jimmer 22]

id def do the earth strap first, its an obvious fault so best place to start.

 

[Paul_TDi]

Earth strap done and still have the fault

The body side of the strap just twisted away from the boot well, so I drilled the hole out a little, sanded back so the metal was clean and stuck a bolt in the hole holding some 3 core cable to the body with a penny washer. On the diff end I cleaned the bolt with some steal wool then same again cable wrapped round bolt with a washer.

Disconnected the battery negative for 10 mins. ( not too sure why but throught it might make the ECU rethink before just chucking up the fault)

Not bothered test driving yet but turn the key to reds and light comes on, goes off for a split second then back on.

 

[Paul_TDi]

As a desperate attempt I had the Haldex serviced, but alas no joy.

It's not a dead cert the haldex reconnects on a warm restart any more now.