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ABS Shuttle valve failure


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After now having the ABS/TC warning lights come on 3 times, and having the fault diagnosed and cleared 3 times, it is confirmed that the fault is being caused by the ABS units' shuttle valve failing.

As i'm sure many will know, a new WABCO ABS unit will set me back approx £1300. Has anyone ever dismantled or had dismantled one of these units in order to sort the problem out, as it seems to be a really common problem with the WABCO unit.

Or is there any way of sorting the problem, ie slamming hard on the brakes every now and then, or bleeding the system?

Any help greatly appreciated.

2004 TD5, hard top 90.

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I didn't think there was a shuttle valve on anything after series? If it is internal to the ABS unit then it might be a sign that you have a leak or issue in the front to rear brake system?

I believe the old series shuttle valve 'detected' loss of pressure in front or rear and moved forward to block fluid from going to the leaking side.

If it exits and has a similar function then it might indicate a weeping line or something?

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  • 2 weeks later...

There is a shuttle valve and switch inside the WABCO unit, i'm seriously considering dismantling the unit in order to see if there is anything i can fix inside the unit. after all, someone somewhere has assambled the unit.

The fault i'm getting is "ABS SHUTTLE VALVE SWITCH FAILURE"

Any ideas?

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Not aware of any known fix and in any case you certainly can't get bits from Land Rover - I would suggest the best thing would be to find a Wabco specialist who might be able to overhaul it.

I should think it is a specialist job and as it is for brakes and therefore rather important, I wouldn't be inclined to pull it to bits and mess about with it on the off chance it might fix it...

It isn't an uncommon problem as you say - I have seen a handful of them here.

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Thanks for that bogmonster,

I have entrusted the job of overhauling it to my mechanic!!! The bottom line is, if he can't fix it, i'll have to have a reconditioned one, there is a place in birmingham that does them with a 2 year warranty for £700. Well, that's got to be better than the main dealers price of £1400+VAT+fitting!!!

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  • 7 months later...

If it's what I think it is, if you take the ABS modulator off and turn it upside down, there is a plastic thingy held on by two allen screws. This is the modulator (or maybe it is called something else) Anyway, you can try changing that - it sometimes fixes the problem without having to replace the whole alloy block thing at enormous expense. At a wild guess it would cost about £100.

All it is really is two microswitches. We have tested ones that work and ones that don't with a multimeter and they seem the same, just that one of them doesn't work. There are only a possible four permutations of on/off.

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If it's what I think it is, if you take the ABS modulator off and turn it upside down, there is a plastic thingy held on by two allen screws. This is the modulator (or maybe it is called something else) Anyway, you can try changing that - it sometimes fixes the problem without having to replace the whole alloy block thing at enormous expense. At a wild guess it would cost about £100.

All it is really is two microswitches. We have tested ones that work and ones that don't with a multimeter and they seem the same, just that one of them doesn't work. There are only a possible four permutations of on/off.

Hi Jim,

The unit thats at fault bolts to the front of the modulator with Lr Rr Fr Lr on top with a bar code and the numbers SRB 100920 98 000. and the brake pipes coming out of it too.. it's all ali..

I feel it can only have micro switches in it too so have asked the guys at my garage to strip it down.. what have we to lose...?

Thanks for your reply

Cheers

Dave

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  • 7 months later...

Curious to the outcome of this. I never get any lights ABS, TC etc (even when I should) and have previously had 'shuttle valve failure'. I was told to 'rally' the landy about on a gravel road and make the ABS system work hard.....tha was two years ago and I have had no problems since then.........touch wood!

That said, my TC doesn't work (ABS does) but I have no errors listed......I can live without it.

Chris

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