Land Rover Discovery 1 ABS problem

[composimmonite]

I've posted previously about a Discovery I've bought and took straight for MOT as a legal way of moving the 70+ miles from sellers address.
Out of the MOT fails (ABS light on, sills, wheel bearings, shock bushes, duff bulb, tyre catching loose bumper end cap & handbrake low efficiency) only the ABS is something I don't know how to start tackling. The actual braking efficiency passed the MOT.
Journey, by most direct / shortest route from MOT station to home is via lanes so on a clear, straight and deserted stretch did an emergency stop from 30 mph. It pulled up straight but left black marks on the road. IMO that means ABS not working as there was no "grating noise" as I get with my other cars nor brake pedal pulsing.

So can anyone give me an idiots guide to how to fault find ABS ?

Cheers.

Paul H

[georgeb]

Not sure on the Discovery, but with the P38, the ABS is driven by sensors on each wheel reading reluctor rings.

First thing is to check the sensors are there, connected up and wired correctly, and at the proper distance from the rings, i.e. seated properly.

The next are the rings themselves. Over time they can become corroded, lose teeth, get gunked up with brake dust and other general detritus.

Generally if there's an ABS issue it's caused by one of the above and replacement or cleaning restores functionality. However, it could be an ECU problem, if the Disco uses them, although that's rarer.

[MiataMark]

Have you tried the Land Rover forums, forums.lr4x4.com/index.php?showtopic=75678 lots of info there but you need to register to download.

[MonzaPhil]

Wobbly wheel bearings will knock the sensors out of place. Just tap them in until they stop with a small hammer and a drift. Be careful of the wires.

Seldom a major failure on Disco 1s normally just the sensor air gaps.

Sent from mine using proboards

[optimusprime]

What discovery is it?
My 200 tdi i don't recall it having abs,i know on discovery2 models that if the hub bearings go then that will cause the abs warning light.
But as has been said they rely on sensor and toothed ring to work, ( which seems like a really bad idea for an off the rd capable motor) have heard lots of stories with them being covered in mud and not working.

[MonzaPhil]

It'll be a 300.

Sent from still mine using proboards

[froggy]

Shuttle valve in the abs unit is the most common issue if it's not been done already

[Battles]

Apr 19, 2015 10:55:09 GMT composimmonite said:

Out of the MOT fails (ABS light on - wheel bearings

I wouldn't be surprised if the ABS light problem goes away when you do the bearings.

[MonzaPhil]

Apr 20, 2015 13:21:20 GMT froggy said:

Shuttle valve in the abs unit is the most common issue if it's not been done already

Shouldn't be a problem in a tdi, more of a td5 issue.

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[composimmonite]

Can somebody clarify.
If there is a fault, such as incorrect air gap at wheel, then the whole system switches off ? ie ABS doesn't work.

[MonzaPhil]

Yes. If there is a fault it will stop working, although sometimes the warning light will be on and the abs will work. It is a land rover after all.

Sent from work using proboards

[Battles]

Apr 20, 2015 16:54:02 GMT MonzaPhil said:

although sometimes the warning light will be on and the abs will work.

One of my W124s does this - incredibly annoying!

[MiataMark]

Apr 20, 2015 14:11:51 GMT MonzaPhil said:

Apr 20, 2015 13:21:20 GMT froggy said:

Shuttle valve in the abs unit is the most common issue if it's not been done already

Shouldn't be a problem in a tdi, more of a td5 issue.

Sent from here using proboards

Yep that's the "3 Amigos" fault on the TD5, been there done that, cured with a wiring mod to improve the earthing. Intermittent and always worse in wet/damp conditions. In this case the ABS, TC etc continued to work despite the light being on.