Disco 2 Shuttle Valve Failure (3As)

Having got fed up of the three mexican fellas popping up on my dashboard, a friend plugged his diagnostic toys into my discovery for me and it came up with the following error codes:

66 Shuttle Valve Switch (Electrical Failure)
69 Pump Failure 2 (pump not running)
134 Shuttle Valve Switch (Electrical Failure)

He reset the error codes, and almost immediately one popped back up:

66 Shuttle Valve Switch (Electrical Failure)

so.... anyone want to suggest what this means and what I need to do? I was fully expecting an ABS Sensor, a bearing fault, etc but not this! And what sort of a bill am i likely to be looking at!

you can buy a used abs block for about 50-100 quid,
or read this
https://www.google.co.uk/url?sa=t&r...oc.cfm&usg=AFQjCNGjZ3H7inkpQt_DsZz5NwNMBAq4lA

The Shuttle Valve Switch plate is located on the underside of the ABS modulator unit and is quite easy to replace without removing any of the brake lines, although care must be taken not to strain any of the lines. There are some clips which hold the pipes secure below the modulator and some on the bulkhead too. Once the pipes are released from those clips, the three bolts holding the ABS modulator can be released allowing access, albeit limited access to the SVS plate.
There is a modification which can be done to bypass one of the biggest problems with the SVS plate; the two pin plug and socket arrangement inside the modulator on which some "dry joints" can develop.
There are a number of pages about doing this mod, both here and online.
Search "svs modification" and "Disco 2 SVS mod".
I've attached a .pdf which might start helping you.
A new SVS plate costs about £40, available on the bay. In the unlikely event of brake fluid contamination, then you probably are looking at having to replace or refurbish the ABS modulator unit.

What he ^^^ said... beside that for the SVS fault definitely make that wiring mod but prior of that you can check the things pointed in this bulletin http://landroverclubvi.weebly.com/u...warning_lamp_illumination_troubleshooting.pdf , except the SVS assy replacement

Thanks folks. Will add it high up on the to do list and look forward to having fully functioning traction control etc (until the next 3As fault appears!)

There are two kinds of plug and socket on those switches that I have seen, one sort has the contacts bright and shiny, the other has dull contacts.

Both sorts worked for me, but I did put some Vaseline on the contacts to keep moisture at bay. Grease must not be used.

Did mine about 4 years ago and hasn't given any trouble since (touch wood) I re-soldered one set of PCB pins and so far haven't really found any that bad that they needed it since.

I think that the switches are more of an issue than doing the wiring modification, that's been my own experience with four D2's.

Peter

I did the wiring bypass/mod. Solved the problem instantly and never had a recurrence.
I've been told that even replacing the shuttle valve switch doesn't always solve the problem.

What I did was plug into the diagnostics to be sure the valves were working. Then did the mod. It was really quite simple and a quick Google search will give step by step instructions

So... i now have the Shuttle Valve in my possession... £30 from a mate and its already had the wiring mod done to it.

Now I just need to find a dry day to fit it onto the landrover and splice the wiring mod into the loom.

When you do get it installed and you're doing the wiring, one side of the switch plate goes to earth, a nearby bolt to the chassis and the other wire from the plate will go to the Green/Yellow wire. Don't splice it in, cut the wire and connect to the "vehicle side", as shown on the attached diagram by BB or Sierrafery.
This will prevent the possibility of shorting the switches out if you get the wiring the wrong way round.

Thanks. So presumably then I just secure the spare end of the wire from the plug on the ABS in some electrical tape out the way?

Yeah, just tape it off and hide it away safely. Job done.

Is there a trick to getting the SVS plate off... have unclipped brake lines to give me a bit more slack, and can get an allen key into the bolts on the underside but cannot get them undone!

Short of removing the brake lines from the ABS any ideas?

private penguin said:

Is there a trick to getting the SVS plate off... have unclipped brake lines to give me a bit more slack, and can get an allen key into the bolts on the underside but cannot get them undone!

Short of removing the brake lines from the ABS any ideas?

Click to expand...

Last time I did one, I unclipped the pipes from the bulkhead and also the three clips around the three pipes below the ABS modulator going down towards the chassis. That does allow you to get a few inches to lift the unit.
I also found that working with assistance, another pair of hands to hold the modulator unit made the job a bit easier.
Fortunately, I didn't need to use a standard allen key, I was able to use an allen key head on a 3/8th" square drive socket set, so torque was easy to apply, but they shouldn't be that tight. Try using "long-reach" keys or a piece of tube to increase the leverage.
There are three bolts, all stainless steel, one at each end of the switch plate and one in the middle.

I did mine in situ as well but my wife kept the modulator lifted untill i worked on the bolts.... i didnt know untill then that she can swear so bad

sierrafery said:

I did mine in situ as well but my wife kept the modulator lifted untill i worked on the bolts.... i didnt know untill then that she can swear so bad

Click to expand...

We wouldn't know, she was obviously swearing in Western Transylvanian

So... turns out that one of the hex screws was rounded off internally. Presumably someone must have messed around with this part before.

Managed to get it out using one of those "knackered screw removers"

Anyway - part switched, new wiring connected up. Still got the 3As lit up. Guess its back to my friend with the diagnostic kit.

Oh, and I seem to have gained a brake warning light as well on the dashboard. Checked fluid level and its almost at max.

Its got dark now so can't really play around with stuff but any thoughts on what to look for would be great. Took the disco for a drive and the brakes etc all work fine.... but still have 3As.

So... didnt get a chance to look at it much today due to the weather. Drive 30 miles, drives fine. Guessing TC wouldnt work due to 3As being on but even on wet leaves it drove fine. Likewise the brakes never locked so didnt get a chance to prove whether ABS is working!

But... the brakes work well. The fluid is on max. The float seems to be working fine. The rear brake lights come on. So why is my brake warning light (handbrake light) on?!

I take it that when you did the wiring, you connected the switch plate to a good ground and the green/yellow wire on the "vehicle side" of the cut, not the little short bit sticking out of the plug on the ABS modulator?
Other than that, the only thing I can suggest right now is to check the codes again, sorry.

When it is a bit drier I will test that the ground i've connected it to is actually a decent ground.