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This is my first post for a very long time, if ever.

I have a 1999 Defender TD5 CSW.

I have the ABS/TC lights coming on whenever I perform heavy braking.

I use my Hawkeye to reset the lights and the DTC is showing its a Shuttle Valve Error;

Of course I have been investigating the problem on the internet and Forums.

I have purchased a ABS Modulator Shuttle Valve Repair Kit (Wabco) SWO500030 from Island-4x4, which I have yet to install.

The Questions I have are:

1. The Shuttle Valve Bypass Mod that is mentioned on a number of sites, says No More ABS/TC Lights. Does it actually bypass the ABS Modulator and stop the ABS/TC from working?

2. The link everyone gives to show the bypass is http://www.landroverclubvi.com/abs-mod.html this doesn't appear to work. Is there another site which CLEARLY shows carrying out this mod. It seems to imply a connection/splice to the Green/Yellow wire going to the modulator and the other going to earth. is this correct?

Thanks in anticipation.


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Why dont you just fit the repair kit, I would recomend a full brake system power bleed and enjoy the vehicle.

I can not open or read the link you gave, but by the sound of what you saying you will not have ABS/TC ? That does sound like a step in the wrong direction, and you need TC because the chance you have a transfer box that you can manually select diff lock is slim.

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Given that were in the defender forum I'd say he has the correct transfer box,

I've done the wiring mod to my discovery which then stopped the lights coming on spuriously but still allowed the tc & abs to work

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There is a good write up on the D2B.co.uk site if you do a shuttle valve mod search. The mod is the same on Defenders and loses no functionality of the ABS or TC ,all it does is to take the shuttle valve switch wires out of the bottom of the switch pack rather than up through the modulator block and out through the front where the circuit tracks break.More difficult on a Defender because there is less room around the unit,but with care and a bit of fiddling can still be done without undoing any pipes or system bleeds etc.

The modulator blocks can also be swopped between Defender and D2 even though the part numbers and pipe layout decals are different.

Guess what I have to do this afternoon...

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Yes they do,just before Christmas I had to sort out a 110 Defender which was fitted with ABS/TC, but some Oik had put black tape over the lamps in the dash.All because the rhf sensor had failed.It was very obvious to me and the tester that the vehicle was fitted with it but the owner has driven it for three years without knowing it had it or that it didn't work....

(Clearly the previous MOT station didn't know or care)

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Can I thank all of you for your answers.

I will have a look at the D2B site.

I was curious about the mod as I dont want to loose ABS. I can live without TC with the Diff Lock.

I assume the ABS/TC lights come on with the Ignition an the initial system check, but dont come on with a fault?

Once again Thank You for your assistance.


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never done it myself, but presume this is the mod in the link above. Essentially its just a set of soldered wires, which as noted above avoid going through the block to the connector.

The shuttle valve switches basically tell the ABS when you are applying the brakes, and therefore turn off the traction control capability and put the abs system in "brake" mode (i.e await to see if the ABS needs to be applied).

The shuttle valves themselves within the block act as a sort of fail safe function where when you are not applying the brakes but the TC is active they stop the fluid from backflowing back up to the reservoir.

by doing the mod as shown on the link everything will work as it is suppose to provided you solder the right wires up, and connect the fly "new" fly leads up to the right wires.

There is a useful guide from Wabco here for you to review, + you don't actually need the testbook, and can use the blink test method (with a defender, not sure about with SLABS [disco II etc, bigger / longer abs controller box]


But you can't bleed it with the "blink test", however, you could make a plug in adapter for the modulator that would run the valves off a few switches.....

blink test - > http://www.meritorwabco.com/MeritorWABCO_document/mm30.pdf

The abs warning lights are looked at the time of MOT inspection as a self test / diagnosis system, hence if they ain't working correctly, something is wrong, and it's therefore a fail.



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I have done this mod and all you are basically doing is re routing the way the wires come out of the modulator block..

Your ABS ? TC will be exactly as it should be..

Bit of a pain to gain access to, I'd take the wing off is I had to do it again..


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