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[tmx]

Got a strange ABS fault on the other halfs Polo the car has a BOSCH ABS system and when you start it up the light comes on and goes out then! when you attempt an emergancy stop the ABS system starts working then fails and all 4x wheels lock up

had it on a VAG Com that a collegue has got and apart from an Idle control valve fault there are no other fault codes on the vehicle

any ideas? im thinking the ABS ECU is faulty but a replacement is £200 so !

[feeutfo]

have had abs issues with our 99 1.6 polo. They dont like pattern sensors and seem sensative to wheel size or flat/low pressure/odd tyres causing intermitent faults it seems. Our issues are on going but seem to have settled for no real reason of late.

From memory, the abs fuse on ours is in the box on top of the battery. These seem to suffer from cracks that at first glance are impossible to see and can cause all sorts of weirdness. Would start there.

Also Vag com has a programme that tests the pump on each corner. May be worth running that?

Another member on here helped me with vag com. Had issues with the subscription until downloaded the latest version, which is improved, and all was well.

[tmx]

Dont suppose you know how you access the Pump test? on vagcom my collegue doesnt really know how to use it very well...!

ABS Fuse on this one is also in the same place they look ok! and ive had the multi meter across it and im getting 12v

[feeutfo]

Dont have access to the software at the moment. It was not obvious on the first version, but very clear on the new version. Maybe needs to upgrade his software?

Also have a good look at the loom a couple of inches from the ecu plug. Peal back some of the insulation and makes sure no damage to the wires, as ours had a repair for some reason. Long shot though.

But ultimately may well be ecu related. May also be worth a chat with BBA reman re your symptoms to see if they think a recon will help.  Youll want them to guarantee it will fix the fault before proceeding.

Thing is the fault only appears when the under high stress of abs cutting in. So all that vibration from the brakes banging away is setting off the fault it would seem. So would call that an intermitent fault imho. That and no codes would imply a circuit brake somewhere. If no wiring fault, or open circuit, can be found your into the gamble and expense of ecu recon or replacment and hope that cures it.

12 vaults at stand still wont necessarily mean 12volts present when abs cuts in if you have intermitent fault.

If vag com has abs live data enabled maybe that will give a clue if the fault occurs when driving and vag com connected. 

Just sounds like a power cut to me. But there are more experienced than me on here.
Anyone?

[tmx]

my mate has got the old version from 2004 hes gonna see if he can have a free upgrade

BBA have said it could well be dodgy wiring as if it was an ECU fault id have no ABS atall they also mentioned what you have said about non VW sensors can cause these sorts of problems this weekend ill take it all apart and clean the sensors up and make sure theyre all genuine VW ones

the car has got a bad earth i think because if you put the heater on with the lights on then take the key out the ignition & hold the mainbeam on the heater comes on

[feeutfo]

  they also seem to suffer from Altzheimers. Ours did when when we got it. Stalling, lights on all over the place buzzers going off. Somebody on here advised that the ecu's where not talking in conjunction.
 Recommended following,

Disconnect battery for 20 mins or so
Reconnect battery and leave ignition on for 20 mins or so. Do not fire the engine in this time.
Fire engine and see if the Gremlins are dead.

Just a re boot i suppose but it worked wonders on ours. Bar the remaining abs issues which where not down to the car really. Crap sensors from German and swedish, odd tyres, one was flat and a bad repair to the loom.

The tolerances on the abs ecu and very tight it would seem. If one wheel doesnt rotate at the almost exact speed as all the others it throws a fault code, esp wheels on the same axle. Kevin Wood put me onto  that one. Also VW mech mentioned the error tolerances where very tight.

Anyway, im rambling, "re boot" wont hurt and may even help, and as said at the start i would dismantle that fuse while the batterys off and remove it from the car to examine it fully. Sort the earth out and try it. Easy and simple stuff first then go deeper from their. We thought we had a nail on our hands but its settled down now.
Good luck.

You have a pm by the way.