Disco 2 3 Amigos and slight brake squeal.

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Sgt Flanders

Sgt Flanders

Member
Posts
26
Location
Merthyr Tydfil
Good Morning all.

Quick question, 3 amigos lit up about 2 weeks ago 2hrs into a 2 1/2 hr trip, almost without warning apart from a slight brake squeal. Reading up on forum posts I'm fingers crossed its brake dust causing it. I'm going to give it a blast with the jet wash to start with before I start dismantling and cleaning. My question is, will the lights extinguish themselves if the problem is removed or do they need reading and resetting with Hawkeye or similar ?
 
They should reset themselves but if not try disconnecting the battery for a while. It is worth getting a check with a diagnostic unit to check whether the problem is at the wheel sensor or shuttle valve fault.
 
Sgt Flanders said:
Reading up on forum posts I'm fingers crossed its brake dust causing it
Click to expand...
I'd be very surprised to see such thing as it has no technical backup whatsoever... nor logic.

The amigos should go out once a fault was rectified and if the fault was wheel speed sensor related he ABS light must stay on alone untill the vehicle exceeds 9.4mph then go out... any other scenarios are not for sensor related faults
 
As this is on a TD5, if you have got all three amigos on constantly, you will need a diagnostic to turn them off. I know cos I've been there (same vehicle) and in the end bought a Foxwell NT pro 520 to do it, as I got fed up of going to garages to get them to do it!
If you only have two on, then it is true that a reset may well trun 'em off.
I'm interested at yet another mention of the shuttle valve being the problem. This because I have read so many posts where people have done the shuttle valve work-around to no avail.
I would imagine the chances are you have a fault with the wheel bearing causing the gap of max 1/2 a mm to be exceeded between the sensor and the reluctor ring, which a new hub will cure. But you may be lucky and the sensor may somehow be covered in sh1t preventing it from signalling properly.
Best of luck
:)
Stan
Edited as post crossed with one from @sierrafery who is the guru of elecrickery. I am surprised he says that you may be able to switch the lights off once the fault is rectified just by resetting and then driving, this was absolutely not my case! and I did try it lots!
 
sierrafery said:
I'd be very surprised to see such thing as it has no technical backup whatsoever... nor logic.

The amigos should go out once a fault was rectified and if the fault was wheel speed sensor related he ABS light must stay on alone untill the vehicle exceeds 9.4mph then go out... any other scenarios are not for sensor related faults
Click to expand...
After I had replaced my hub, the lights stayed on and wouln't go out, despite my resetting via disconnecting/reconnecting the batt. And driving at the correct speed. So I am interested you say this. I could only do it with a diagnostic. (The Foxwell that you recommended, which is brilliant, by the way.;)
 
The shuttle valve mod won't help if the fault is at the wheel sensor, just as doing anything with the wheel sensor won't help if the fault is shuttle valve related. That is why I said that a diagnostic unit can identify where the fault is. With mine it was the shuttle valve and I have had no trouble since doing the mod. Without a diagnostic unit it is just like flipping a coin.
 
brianconwy said:
The shuttle valve mod won't help if the fault is at the wheel sensor, just as doing anything with the wheel sensor won't help if the fault is shuttle valve related. That is why I said that a diagnostic unit can identify where the fault is. With mine it was the shuttle valve and I have had no trouble since doing the mod. Without a diagnostic unit it is just like flipping a coin.
Click to expand...
Absolutely agree. There just are times when a diagnostic is better than playing "pin the tail on the donkey"!
But STILL interested in what causes the shuttle valve fault. Did you find out what it was in your case? Or did you just have to treat the symptoms?
 
Looks like I am outnumbered here!
Still don't know why though!
Still I am sure the diagnostic will prove useful in other ways!
 
Stanleysteamer said:
After I had replaced my hub, the lights stayed on and wouln't go out, despite my resetting via disconnecting/reconnecting the batt. And driving at the correct speed. So I am interested you say this. I could only do it with a diagnostic. (The Foxwell that you recommended, which is brilliant, by the way.;)
Click to expand...
Then it was some strange glitch, it can happen but it's not normal behaviour... also the so called ''hard reset" wih battery disconnection on a D2 is useless cos that's valid for CAN-bus vehicles only.... any effect of that on a D2 is also accidental
 
sierrafery said:
Then it was some strange glitch, it can happen but it's not normal behaviour... also the so called ''hard reset" wih battery disconnection on a D2 is useless cos that's valid for CAN-bus vehicles only.... any effect of that on a D2 is also accidental
Click to expand...
Thanks for that!
I thought I read somewhere that when disconnecting the batt you had to do it within 15 secs of turning the key off, something to with the alarm if I remember rightly.
But you are saying that you can simply connect it back up and then drive away? No need to give anything any time to get "intialised" or anything?
With wifey's Citroen you have to go through a whole rigmarole when it comes to disconnecting and reconnecting. "wait 1 minute between switching off and disconnecting", wait so many more minutes before reconnecting, wait so many minutes before switching, wait yet more time between switching on and starting and in the meantime push the brake pedal once" Right PITA! And her's is only an 04 car.
Anyway, maybe I was confusing the two, will have to see if I can find where I read this!
 
Sgt Flanders said:
Good Morning all.

Quick question, 3 amigos lit up about 2 weeks ago 2hrs into a 2 1/2 hr trip, almost without warning apart from a slight brake squeal. Reading up on forum posts I'm fingers crossed its brake dust causing it. I'm going to give it a blast with the jet wash to start with before I start dismantling and cleaning. My question is, will the lights extinguish themselves if the problem is removed or do they need reading and resetting with Hawkeye or similar ?
Click to expand...

The brake squeal is probably because when an ABS fault is detected, the SLABS disables ABS and the system reverts to conventional braking. A fault with the ABS modulator registers as a permanent fault and needs to be cleared with a diagnostic tool after rectification. Faults registered at the wheel will clear automatically once you start driving following repairs, which normally involves installing a new sensor or replacing the entire wheel hub. A diagnostic tool will be needed nonetheless as for a start, you will need to know which wheel out of the four is causing the problem. Garages charge ridiculous amounts to give you this basic information so it makes a lot of sense to have your own. And if you need to change the hub, get one with a 60 tooth exciter ring as you'll find others on the market that have fewer teeth. These are usually very cheap but do not conform with the ones originally installed and will confuse the SLABS with incorrect readings.
 
It was a shuttle valve fault on mine but it didn't cause lights to stay on permanently. Sometimes they stayed on and sometimes they didn't. I had a lynx diagnostic at the time which told me it was a shuttle valve switch fault. Have never had any trouble after the mod.
 
brianconwy said:
It was a shuttle valve fault on mine but it didn't cause lights to stay on permanently. Sometimes they stayed on and sometimes they didn't. I had a lynx diagnostic at the time which told me it was a shuttle valve switch fault. Have never had any trouble after the mod.
Click to expand...

Strange as it seems that the fault on your system was registered as an intermittent / pending fault, and hence why it cleared automatically after the fix. But to clarify, just had a look at RAVE and this is what it says - "A shuttle valve switch fault and throttle position signal fault are classified as permanent faults. If a permanent fault is detected, the related warning lamp illumination and default strategies are automatically employed in subsequent ignition cycles, even if the fault is intermittent, until the fault has been rectified and cleared from memory."
 
NPG said:
The brake squeal is probably because when an ABS fault is detected, the SLABS disables ABS and the system reverts to conventional braking. A fault with the ABS modulator registers as a permanent fault and needs to be cleared with a diagnostic tool after rectification. Faults registered at the wheel will clear automatically once you start driving following repairs, which normally involves installing a new sensor or replacing the entire wheel hub. A diagnostic tool will be needed nonetheless as for a start, you will need to know which wheel out of the four is causing the problem. Garages charge ridiculous amounts to give you this basic information so it makes a lot of sense to have your own. And if you need to change the hub, get one with a 60 tooth exciter ring as you'll find others on the market that have fewer teeth. These are usually very cheap but do not conform with the ones originally installed and will confuse the SLABS with incorrect readings.
Click to expand...
This is extremely interesting and a clear explanation of what can happen.
All I can say is that, according to this, I should have had a shuttle valve fault, but it somehow cleared itself. The hub definitley was not doing its job properly as that showed up on the diagnostic and kept showing until it was changed. But the shuttle valve never threw a fault code.
Anyway, thanks for this.:)
 
NPG said:
A fault with the ABS modulator registers as a permanent fault and needs to be cleared with a diagnostic tool after rectification. Faults registered at the wheel will clear automatically once you start driving following repairs, which normally involves installing a new sensor or replacing the entire wheel hub.
Click to expand...
That's how the system was conceived to work but it's not doing it all the time especially not with intermittent/partial faults. The red brake lamp should be always together with 3 amigos as well but it's not. I observd that the protocol as it's described in the manual behaves like that only when the faults are ''solid'' open or short circuit, when the faults are just ''partial'' the protocol is erratic too from one case o an other

ABS diagnostics.jpg

NPG said:
The brake squeal is probably because when an ABS fault is detected, the SLABS disables ABS and the system reverts to conventional braking.
Click to expand...
On normal braking mode when the pedal is used without any ABS activity the system is as "conventional" anyway like when the modulaator is unplugged. The modulaor comes into play only when ABS, TC, EBD, or HDC actions are required.
 
sierrafery said:
That's how the system was conceived to work but it's not doing it all the time especially not with intermittent/partial faults. The red brake lamp should be always together with 3 amigos as well but it's not. I observd that the protocol as it's described in the manual behaves like that only when the faults are ''solid'' open or short circuit, when the faults are just ''partial'' the protocol is erratic too from one case o an other

View attachment 199136
On normal braking mode when the pedal is used without any ABS activity the system is as "conventional" anyway like when the modulaator is unplugged. The modulaor comes into play only when ABS, TC, EBD, or HDC actions are required.
Click to expand...
This is fascinating, yet again!
Also, when I had my three amigos on I was away for two weeks in Scotland at Christmas, so just had to put up with them. There was very little snow, but there was ice so I was concerned. So I tested both the traction control and the ABS and both seemed to work, so I really do not know what was going on!;):)
 
sierrafery said:
The red brake lamp should be always together with 3 amigos as well but it's not.
Click to expand...

Very true.

sierrafery said:
On normal braking mode when the pedal is used without any ABS activity the system is as "conventional" anyway like when the modulaator is unplugged. The modulaor comes into play only when ABS, TC, EBD, or HDC actions are required.
Click to expand...

This is correct but there's also the EBD function that will not work when the ABS modulator is taken offline. Under normal braking conditions and without the 3 Amigos, it is hard to detect when EBD activates but it does and acts as a brake fluid pressure regulator. With the 3 Amigos on, one can therefore suggest that the brake force might not be exerted equally across the 4 wheels, causing the wheel(s) with the higher load to squeal.
 
Stanleysteamer said:
EBD? Does this exist on a Disco 2? I don't think mine has it (2000) or is it only on version 2 Disco 2s or ES models or summat?
Click to expand...

Yes, it is incorporated as an extension of the ABS system. When faulty, SLABS will illuminate the brake warning lamp on the instrument cluster , which is also used for handbrake and low brake fluid.
 
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