ABS
 

Hey guys, I've got a MK5 RS2000. I had a Clifford alarm system fitted to it, when i picked it up the ABS light was on. I asked the bloke about it and he said come back next week, which i did and the shop went bust. :wall:
Any suggestions on how to fix it?

Hiya

The ABS light will indicate a fault and pinpoint it in the way the light gets displayed, this may help:


Written by MarkN

The Teves (IV) ABS System on Mk5/5a/4x4 tests in two stages.

When you first turn the ignition on to pos II the ABS does as self test, and you get a characteristic "CLICK" from under the bonnet when the pump/valve assembly powers up. If you don't get this click, it could be a faulty pump/valvle unit or the wiring between that and the ECU. Or the ABS pump/fuse at the fusebox.

The second stage of the test starts when you drive off fowards and exceed 5mph(if I remember rightly). The ABS knows you are going this fast because of the Hall Effect sensors on the front wheels. Now the ECU runs a test on the valve assembly and very quickly pressurises the different hyraulic circuits. If something fails at this stage the ABS light will illuminate. This is often mistakenly diagnosed as ABS sensors.

To summarise:
Light doesn't illuminate at all: Possibly faulty ABS module, blown system fuse/relay, blown bulb, or blub removed by unscrupulous car dealer trying to diagnose a fault.

Light illuminates immediately but won't go out: Faulty pump unit or pedal switch. Disconnected or faulty Hall effect sensor. Faulty wiring harness or fuse box.

Light illuminates after moving off: Blown pump fuse/relay. Faulty or dirty Hall effect sensor. Faulty valve assembly.

Thanks mate, I'll give that a go!

Just to be sure: You let someone else put an alarm in.You left your car there, before ABS was working as it should, afterwards it doesn't?

Then there are three possible solutions.

1. Alarm wiring affects ABS so it doesn't work properly. Or the wiring causes just the lamp to indicate.
2. While they put the alarm in and did the wiring they caused a short circuit and burned down something of the ABS. Maybe just the fuse
3. While the car was there they did something else that had some kind of an effect to the ABS.

Are all ABS parts still in position? ;)
Are the brakes working after all?

Hiya Icarus - not spoken to you for years :-). It's a real blast from the past seeing that old ABS diagnostic text I put together; - I must have written that nearly seven years ago lol. Still got your RS2000?

In terms of this ABS fault - a lot of the key ABS wiring goes through the main fuse box which has presumably been pulled about considerably when the alarm has been fitted. This could potentially have affected one of the power feeds which could cause either the instant or delayed light symptoms above.

Simple things first and all that - check the two ABS fuses (can't remember which ones they are now), and the two relays. Whilst you've got the fuse box dropped down check all the plugs are fully pushed in as they sometimes come out when the box is dropped down.

Years back when I had the ABS problem the light would go out and then come on again when you moved off. I was convinced it was a dodgy sensor - but they seemed ok. Ultimately it turned out to be a burnt out track in the fuse box which I fixed with a 10p piece of wire. Soddin Ford and their cheapo fuse boxes :angry: