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Discussion Starter · #1 ·
I'm getting a Shuttle Valve Switch code, and want to replace the shuttle valve seals along with the switches. Yes, there is a sticky on this subject, but the link provided now points to LandRoverUSA.com rather than the original site. I'd like to know what I'm up against here. Can anyone point me to another resource or provide some further guidance?

Thank you,
 

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http://landroverclubvi.weebly.com/abs-svs-seals.html

I'm getting a Shuttle Valve Switch code, and want to replace the shuttle valve seals along with the switches. Yes, there is a sticky on this subject, but the link provided now points to LandRoverUSA.com rather than the original site. I'd like to know what I'm up against here. Can anyone point me to another resource or provide some further guidance?

Thank you,
 

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I'm getting a Shuttle Valve Switch code, and want to replace the shuttle valve seals along with the switches.
Please note there is a high probability that replacing the shuttle valve switches and the seals won't chase away the Three Amigos, despite the SVS fault code.

More often than not the switches and the seals are fine and the problem is with a related solder joint buried in the modulator body that fails.

If I were you I would instead do the Option B bypass outlined the sticky linked above. It takes about an hour and only a few dollars worth of supplies (a two-wire trailer lighting harness, a ring terminal for the ground, a little heatshrink tubing and a little solder). While you have the switches out you can test them and inspect for leaking seals as outlined in the sticky.

Good luck.
 

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I made a scheme about the issue using the modulator's internal diagram from WABCO to explain what's going on, the possible problems are pointed with the orange circles, can be only one or more at the same time so the mod is what's shown with the purple lines, this way the whole problematic section is bypassed giving the switch pack's input directly to the YG wire which is hardwired to the ECU, as long as the switch pack keeps the resistances within the expected range there will not be SVS related 3 amigos anymore.
 

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Discussion Starter · #5 ·
Please note there is a high probability that replacing the shuttle valve switches and the seals won't chase away the Three Amigos, despite the SVS fault code.
I've read the articles posted. In this case, one of the switches was well soaked with brake fluid, so at least one of the seals was sure to be leaking. You can electrically test the switches easily enough and in the case they're not bad, then your problem is clearly elsewhere. I did not do the "option B" as I deemed it unnecessary at this time. Of course, time could prove me wrong.

So far, so good. 100 miles or so on it since the fix and the Three Amigos are nowhere to be seen.

Oh, BTW, I bought a new scan tool to do the modulator bleed. It's a Foxwell NT630 Pro, cost about $100 and did the job fine. It's a lot cheaper than a Hawkeye.
 

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I could have written the above post. Although I didn't have any leaking seals, I replaced the switches and no longer have the 3 Amigos. I found the 2-pin connector on the switch board had a slight amount of corrosion (very minor, but enough to break the connection). I could have cleaned it but since I had the new switch board, I put it in. As above, about 100 miles and so far, so good. I also use the Foxwell NT630 Pro and really like it. Option B is a better long-term fix but this was easy and I'm a bit lazy.
 

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Discussion Starter · #8 ·
I second the Option B approach. Put the switchpack in my son's, now a few months later he has intermittent Amigos.

I hate paying for the same ground twice.
Did you test the switches electrically at the time you replaced them? Was there evidence of leakage from the shuttle valve seals, and did you replace those? Is a shuttle valve switch failure the cause of your new fault? There are other things that cause Three Amigo visits. The point is there are three failure modes (that I'm aware of, anyway) in these problematic abs modulators.

1) switches fail all on their own
2) seals leak, take out the switches
3) contacts in the PC board go bad, masquerade as switch failure

"Option B" addresses only failure mode 3, not 1 or 2. You can have 1, 2 or all three problems. If you really want to know, you have to test the switches and the contacts in the PC board to determine what really is bad. And look for fluid leakage, of course. I would never advocate hacking into original wiring unless I knew it was bad and could prove it by testing. I've paid "experts" in the past to hack into wiring to solve a problem only to find it didn't solve the problem at all, and then I had to not only fix the original issue, but the hacked up wiring as well.

Just saying you should test before you start hacking away at something you can't easily replace.
 

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No leaks. Bad switches. Problem resolved for 6 months. No sign of leakage now.

Option B isn't really hacking. it's a wire relocate that can easily be undone, but I wouldn't know why someone would want to. All it does is remove one flaky connection and replace it with hard wiring.
 

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Discussion Starter · #10 ·
Eating Crow

Time to eat crow. A few weeks after I replaced the shuttle valve switches, the Three Amigos returned, again with the Shuttle Valve Switch Electrical Failure code. I tested the old switches electrically, which I should have doe when I first removed them, and they were fine, so clearly the PC board inside the modulator was at fault. I lived with the intermittant lights for the last few months, but finally this past weekend I made the "Option B" mod to the old shuttle valve switches and swapped that back in. That is clearly the easiest way to go about fixing that problem and I didn't have to break open the hydraulic lines again.

The lights are gone for now. Only time will tell if this is the final answer or not, but don't say I never admit when I'm wrong.
 

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