Disco II brake modulator bleeding

I have year 2000 Disco II V8 with a Wabco modulator unit which helps to control the flow of brake fluid to the brakes when ABS, Hill Descent or Traction Control are required. I have recently experienced the dashboard "ding" accompanied by the three warning lights for ABS, HDC and TC coming on. Usually these can be reset by stopping the vehicle and restarting it (when did Landrover start used Windows 98 in their vehicles?). Considered opinion is that this is caused by the shuttle valve assembly getting long in the tooth. Mine being 11 years and 58k miles could well fit into this category.

So I've bought an OEM replacement shuttle valve assembly which appears to be a simple three bolt replacement job onto the base of the modulator.

But a final read through of the service manual suggests that if I disconnect the modulator from the master cylinder pipes and the pipes that go to the wheels then I need to bleed the system using the Testbook/T4 proprietry software.

Is this true? If I take the modulator out, plug the six open ports, invert it and change the shuttle valve assembly am I going to be stuck with taking it to a Textbook/T4 facility after I have reinstalled it and having them bleed the system more thoroughly?

That's correct, but if you find someone with a Hawkeye unit the you will be able to open the modulator valves for bleediing out the air as a DIY function at home.

You can change the shuttle valves without removing the ABS modulator hence no brake bleeding afterwards. Have a look at his video on you tube [nomedia="http://www.youtube.com/watch?v=l7hZQI1gfAg&feature=player_detailpage"]‪ABS TC HDC LANDROVER DISCOVERY II WABCO‬‏ - YouTube[/nomedia]
It also demonstrates how to check the shuttle valve switches and modify the wiring if they prove to be OK (common occurrence). There is also a detailed write up of the procedure on here somewhere.

i have done it without removing or disconnecting the modulator. Is a bit of a pain to do but just need to take your time. needs a bit of thime to get the modulator into a suitable position

Well done :clap2:

steadyaway said:

You can change the shuttle valves without removing the ABS modulator hence no brake bleeding afterwards. Have a look at his video on you tube ‪ABS TC HDC LANDROVER DISCOVERY II WABCO‬‏ - YouTube
It also demonstrates how to check the shuttle valve switches and modify the wiring if they prove to be OK (common occurrence). There is also a detailed write up of the procedure on here somewhere.

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hello mate any clues or even better find the detailed write up you mentioned im just going through threads at the moment. as all my lights are up atm:doh:

thanks.

you only need to slacken and press pedal down and retighten before letting pedal up on each outlet in turn till runs free of air,i have hawkeye but never needed it even with fitting new modulators

Have a read of this ABS Mod - LAND ROVER CLUB V.I.
I did it on mine about 9 months ago and no lights since. I bought a waterproof plug off fleabay for about a quid. All the systems work, it is not a way of just turning the lights off. Get back to me if you want some info on the plug.

Thanks for everyones help. I fitted the new switch assembly without any trouble and the problem seemed to go away. However 800 miles on it is back although very infrequently. I'm going to look at the rewiring suggestion and also the waterproof plug. Again thank you to everyone.