Hi Francis, do you know the exact fault that was displayed when the diagnostic system was checked?
Was it plugged into a diagnostic computer?

Saying the ABS control unit is faulty seems to me to be a bit of a cop-out excuse used by garages that don't actually know what the fault is.

 

Sounds like another situation were diagnostic equipment can't figure out what is wrong.
I suggest the all wheel sensors be checked for continuity - then have a look at the connections going to the ABS unit which is located in front of the front left wheel under the plastic cover.

 

Indicater fault good be a bad earth in the rear light cluster

 

I had a little problem with my ABS a few years ago and it was a connector going to the O/S/R wheel speed sensor.
The connector had corroded and lost it's connection.
Also the wires are prone to oxidising and could also show a faulty connection.

 

If the brakes are working ok is an ABS error an MOT failure? Don't see why it should be ... ? Or are the two systems not independent, so when one is fubarred the whole thing is?

Cheers!

:d

 

Nope, apparently, if you have ABS, there must be no warning lights about it else it's an MOT failure. Bit stupid really, but I suppose it enforces the best level of safety possible.

 

Its not that stuipd really as the brakes run through the abs unit and therfore if you have a fault on it you could loose you braking altogether.

 

I don't think cars with ABS would be allowed on the road in the first place if that were the case!

I've certainly never heard of a car with an ABS fault losing braking...

 

The should fail safe. but as you run from the master cylinder to the abs unit then out to the wheels there is a potential for a failer of all braking but like every thing on a car its how likley is it to happen. I mean they check things on the mot that shouldn't fail but there is the potential there for it to happen.
With abs you have a waring light come on to tell you theres a problem at which point most people will get it looked at at least.

 

Normaly if there is a fault in the ABS system it will go into default mode - that is non ABS but direct pressure. Try braking hard in a safe area and see if any of the wheels lock up. 90% of ABS faults are usually down to poor electrical connections or faulty ABS sensor rings which can come adrift or get gummed up. The ABS ring is part of the wheel bearing on the Lag II. Apart from checking the connections to the sensors it is also worth checking the connector to the ABS controller box which is situated behind the left front bumper on the Lag II and can be accessed by removing the inner front left mud catcher