Disco 2 Dreaded mot faults

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alexc2701

alexc2701

Active Member
Posts
680
Location
Nottingham
Hi guys took the D2 for its mot today, was hoping the three amigos would stay silent but sadly they popped up and counted as a fail! :rolleyes: surprise since the defenders not sorted yet I actually need to fix it soonish, he diagnosed it and it came up as a abs valve problem. Two questions one is it actually a likely cause? Rarther than sensors since mates said valve and it wasn't after spending moolar.
And two is it easy to refirb/change?
Got drag links to swap too luckily fixed most the other issues in ujs and leccy but bound to be something! The usual advisories about leaky ace and ball joints
Any help much appreciated!
Also when I've fixed the valve do I need a diagnostic to reset the warning light? Thanks guys!
 
If you're good with a soldering iron the costs for repairing the SVS electrical fault should be approximately the best part of not a lot, in other words zero. It all depends on exactly what the problem is, but you saying that "it came up as a abs valve problem" does suggest to me that it is the shuttle valve switches. If the switch plate is faulty then it could cost about forty quid for a replacement switch plate.
Search either here or on Google for "SVS mod".
If it's a fault in the actual ABS modulator, then that won't be cheap, you'd be best off going for a reconditioned unit, so just hope it's the switches on the shuttle valve plate.
Unfortunately the modification is unofficial so the garage might not want to do it for you, mainly to cover their backs.
Once the fault has been cleared then the logged historic codes in the SLABS ECU will have to be cleared using a compatible code reader.
 
brian47 said:
If you're good with a soldering iron the costs for repairing the SVS electrical fault should be approximately the best part of not a lot, in other words zero. It all depends on exactly what the problem is, but you saying that "it came up as a abs valve problem" does suggest to me that it is the shuttle valve switches. If the switch plate is faulty then it could cost about forty quid for a replacement switch plate.
Search either here or on Google for "SVS mod".
If it's a fault in the actual ABS modulator, then that won't be cheap, you'd be best off going for a reconditioned unit, so just hope it's the switches on the shuttle valve plate.
Unfortunately the modification is unofficial so the garage might not want to do it for you, mainly to cover their backs.
Once the fault has been cleared then the logged historic codes in the SLABS ECU will have to be cleared using a compatible code reader.
Click to expand...
Thanks for the reply I didn't realise he'd only put valve on the paper and when I realised could be shuttle or solenoid valve they were closed so I couldn't check! All he said was a valve inside the abs pump? I'm not too familiar with the newer fandangle electrics in cars but I can solder so I'll look that up now cheers
By the way how will I know if it is this or the modulator? Or is it a case of do the mod and if still there the modulator? I was trying to remember that word all day when he said valve! Modulator was on my friends think he got a 2nd hand one for 80, after being quoted 400 for a new one!
 
It has come up with varying lights too sometimes just abs but mostly three amigos was hoping they'd stay hidden for test but oh well
 
Looked up that fix, hope it is that it seems pretty simple to fix, just a variable resistor one end to ground one end to yg, few crimps be sorted! Just looks annoying to get at haha. Thanks for the advice
 
The Shuttle Valve Switch problem is actually inside the ABS modulator, but the modification is a work-around for the problem area. The reason for the fault is a small two pin connector inside the modulator which connects to the switch plate and one or other of those pins develops an intermittent connection.
If the brakes work as they should, there's every likelihood that the ABS modulator is working, but by removing and examining the switch plate you should see that it's dry. If it is covered in brake fluid then you're going to have to get some work done to replace the seals, at least inside it.
If you have access to a Nanocom code reader then the fault will be logged as "SVS electrical" and intermittent faults logged then that's 90% certain it is the switch plate.
I think you're looking at a different modification, I've attached the correct version for you. Most people refer to it as the "Option B mod".
To be honest, if (when) I start having the 3 amigos then the first thing I will do is install the mod and if it doesn't do the trick, then I'll start looking elsewhere for the trouble.

@sierrafery has also put some very useful information on the forum about this problem, including a circuit diagram which shows the modification, but I can't remember where it is right now.
 

Attachments

  • OPTION B.pdf
    1.1 MB · Views: 173
brian47 said:
The Shuttle Valve Switch problem is actually inside the ABS modulator, but the modification is a work-around for the problem area. The reason for the fault is a small two pin connector inside the modulator which connects to the switch plate and one or other of those pins develops an intermittent connection.
If the brakes work as they should, there's every likelihood that the ABS modulator is working, but by removing and examining the switch plate you should see that it's dry. If it is covered in brake fluid then you're going to have to get some work done to replace the seals, at least inside it.
If you have access to a Nanocom code reader then the fault will be logged as "SVS electrical" and intermittent faults logged then that's 90% certain it is the switch plate.
I think you're looking at a different modification, I've attached the correct version for you. Most people refer to it as the "Option B mod".

@sierrafery has also put some very useful information on the forum about this problem, including a circuit diagram which shows the modification, but I can't remember where it is right now.
Click to expand...
Ah I was looking at that, I just skipped the bit that said modulator! So that makes sense, I saw the part about brake fluid I think it sounds more likely electrical since it doesn't always come up, usually after afew bumps or heavy braking, basically when things get moved about which lines up with a loose connection. I'm assuming since it isn't always on, it makes sense to assume the actual shuttle switches must be okay resistance wise, or it'd come on every time.
I'm most annoyed about tyre cos tons of tread on it so waste cos of stupid cut, and the drag link! The garage said nearly 200 to fix one joint! Dunno why you'd ever do that since can buy the whole assembly for like 26-80 quid. And then just afew bolts no pressing in joints! Flagged a corroded pipe that's just where the paint has fell off as advisory. Odd
Ace is leaking too but who's isn't. When it becomes problem probably swap for springs. Think you need a nanocom to stop it showing as a fault though?
 
@alexc2701
I've done the SVS mod successfully for a number of people and the last time I did it, it took about an hour. There's no need to remove the ABS modulator from the vehicle, nor undo any of the brake lines. You will have to carefully ease the modulator unit up out of its mountings to gain access to the plate on the underneath.
I think that any of the compatible code readers; Nanocom, Hawkeye or Lynx will clear the fault codes on the SLABS.
Regarding the ACE, um, not everybody's ACE leaks, but it does require abit of work to do it properly. As I said on another message, @MJI is the ACE ace at the moment.
You said, "Ace is leaking too but who's isn't. When it becomes problem probably swap for springs". I would venture that you're making a common mistake of confusing the Active Cornering Enhancement (ACE) with the Self-Leveling air Suspension (SLS). The two are entirely different and separate systems. ACE uses hydraulic rams in place of static anti-roll bars and the SLS uses rubber air bags in place of steel coiled springs and never the twain shall meet.
 
Ah I got told to swap one you had to do the other aswell to do with fault codes or something? If that isn't the case even better. Can you put in static arb's and disconnect the ace entirely? Because I quite like the bags over springs, I know you have the possibility of them popping but they're comfy and versatile. It half self levels when towing too how it pumps up.
That's good if you can just lift the unit rarther than disconnecting the lines I didn't want to have to bleed the system can do on my own if just the leccy fix. I only got this temporary while I do up my 90 learning lots, and that anything with electrickery and computery bits is annoying. My ye old 90 is way more simple :D
 
The current thinking is that it's cheaper to repair the ACE system than to remove it and replace it all with static anti-roll bars, but it can be done.
The SLS system is a good system but you should consider replacing the air bags every five years or so, after all they're just rubber tubes filled with compressed air, just like four other rubber tubes of compressed air on the vehicle.

Here are a couple of links to some sites which show in practical terms how to ease the ABS modulator up to get at the SVS switch plate:
https://www.youtube.com/watch?v=l7hZQI1gfAg

http://www.handyhowie.co.uk/handyhowie/Disco_ABS_Fault.html

Here's the circuit diagram of the electrics in the ABS modulator showing how the modification fits into the grand scheme of things.

Shuttle valve wiring.jpg
 
Ah that makes it seem super simple don't even need to get a particular end to earth either will work looking at that since its just set resistances and switches. Howcome when I looked up amigos tons if posts on sensors and hubs and all sorts this looks like a far easier and more likely issue to go to first!
The video makes it look abit easier annoying but not so bad. Job for the morrow or sat sorted haha.
Surprised the ARB'S so expensive. I wonder if you can just take them off entirely since not all vehicles have them. My defender has nothing they're only MOT able if they're fitted. Might be diffirent since standard on disco though
Leak isn't bad anyway doesn't even drip on drive not had to top up in a year.
It's good how helpful people are here, most people in real life wouldn't put in the effort o_O
 
alexc2701 said:
Ah that makes it seem super simple don't even need to get a particular end to earth either will work looking at that since its just set resistances and switches. Howcome when I looked up amigos tons if posts on sensors and hubs and all sorts this looks like a far easier and more likely issue to go to first!
The video makes it look abit easier annoying but not so bad. Job for the morrow or sat sorted haha.
Surprised the ARB'S so expensive. I wonder if you can just take them off entirely since not all vehicles have them. My defender has nothing they're only MOT able if they're fitted. Might be diffirent since standard on disco though
Leak isn't bad anyway doesn't even drip on drive not had to top up in a year.
It's good how helpful people are here, most people in real life wouldn't put in the effort o_O
Click to expand...
There are two main reasons why the 3 amigos can pop up. Amongst them is the SVS electrical problem and the other main reason is a faulty speed sensor signal to the SLABS ECU from one or more wheel hubs. Under those circumstances it's almost essential that the fault codes are scanned to isolate exactly which hub is at fault before you start on repairing the problem.
Since in your first post you talked about a valve fault it was a fairly safe bet that it was the shuttle valve switches.
I would advise against removing the anti-roll bars completely, it's likely to cause adverse handling and secondly, we've just had a post from another member asking about exactly that and it turns out that it's an MoT failure if ARBs were originally fitted they must be present for the test.
 
brian47 said:
There are two main reasons why the 3 amigos can pop up. Amongst them is the SVS electrical problem and the other main reason is a faulty speed sensor signal to the SLABS ECU from one or more wheel hubs. Under those circumstances it's almost essential that the fault codes are scanned to isolate exactly which hub is at fault before you start on repairing the problem.
Since in your first post you talked about a valve fault it was a fairly safe bet that it was the shuttle valve switches.
I would advise against removing the anti-roll bars completely, it's likely to cause adverse handling and secondly, we've just had a post from another member asking about exactly that and it turns out that it's an MoT failure if ARBs were originally fitted they must be present for the test.
Click to expand...
Ah I see
That must be why get away with it on defenders since they're extra/optional not always fitted don't need kinda thing. It does make a big diffirence though you're right my friend fitted some on his 90 stops it bouncing like a boat as much
 
20171027_173452.jpg 20171027_173739.jpg
Sounds like hose is the way to go; mines barely a seep tbh he was just picky.
Fixed abs tonight the guide was good cept where it says take off the front 8 bolts which you don't need for mod b haha. Wad a pig for bottom bolts went back together in half the time though. If I'd known so easy (and free) id've fixed sooner
Neighbors moaned only had van on pavement few hours (legally parked) wish people like that would get ran over
Much thanks
 
alexc2701 said:
View attachment 134109 View attachment 134110
Fixed abs tonight the guide was good cept where it says take off the front 8 bolts which you don't need for mod b haha. Wad a pig for bottom bolts went back together in half the time though. If I'd known so easy (and free) id've fixed sooner
Click to expand...
Glad you got the 3 amigos sorted, but I don't remember anything about "the front 8 bolts" in any of the attachments or links which I sent you.:confused::D
 
brian47 said:
Glad you got the 3 amigos sorted, but I don't remember anything about "the front 8 bolts" in any of the attachments or links which I sent you.:confused::D
Click to expand...
I pulled up the origional like an idiot to see how to get at the svs which shows taking the side opposite the pump off to access the pcb whereas I did the b option like you said (way better) so undid all those for nada. The rubber mounts are really awkward to get out when you don't disconnect the brake lines. Saved faffing bleeding though. Can't find anywhere selling drag link local now haha wanted to sort tomorrow probably have to order and wait for parts
 
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