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Disco ABS


LexLoci

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Hi all,

Firstly, please bear with me, i've never owned a disco before and until a couple months ago knew absolutely nothing about them, so go easy, us females don't absorb mechanical knowledge as easily :P

Basically I bought my somewhat modded Disco in March, and it had the ABS light on. I figured its something me and my friends could fix pretty easy, however its never actually caused a problem so we never got round to it until now, since the MOT is going to run out soon...heh.

Was wondering where to start trying to work out the problem, and what the usual things to go wrong with the ABS are...I've been told something about shorting something to get a flashy light that is an error code, but i'm not 100% sure on what to do.

Any help would be muchly appreciated :)

Ta,

Lana

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Hi There,

When I bought mine, the garage that sold it to me gave it an MOT. When |road tested it I saw the ABS light was on, and when I took delivery it was off, it got two other mot's since then, and now I find out that to fix it they took the bulb out!

On abs, the most common fault is the wheel sensors, check them with a multi meter. They should all be about the same resistance. If you haven't got a meter, Maplins do a useful one for £5.

Good luck.

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Is the ABS light on all the time? It should come on when the engine is first started, and then go out a few seconds after. Faults can be anything from tyre sizes not being identical, to knackered brake pedal switches (a favourite on MG rovers....). The electrical pick ups on each encoder ring on the hub, may have a bad connection. If it has been modded and off roaded, then the connections could just be full of water and subsequently corroded. I dont know if the resistance method will work for checking the pick ups. Normally they are 'hall effect', so may have 3 wires (positive, negative and the pulse output). If the ABS light goes off at first, and then comes back on once you are over 5mph, then the pick ups are the first thing to check.

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Brilliant, thanks for all your replies, lots of stuff to try! Ta muchly :D

P.S Karlo the disco in your avatar look amazing - is exactly what i'm aiming for mine to look like when i'm done with it ^_^

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  • 4 weeks later...

Hey,

I am currently helping Lana with her ABS system. It is a bit of a mine field.

The vehicle is a 1994 300tdi but it is fitted with the later Wabco ABS so you use the later vehicle diagnostic plug, however the warning light relay corresponds to the older Lucas system. :S

Either way I got it to spit out codes however all it does is kick out code 2-1, even after clearing. But 2-1 doesn't exist lol....

any ideas? I am confused!

Adam

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Brilliant, thanks for all your replies, lots of stuff to try! Ta muchly :D

P.S Karlo the disco in your avatar look amazing - is exactly what i'm aiming for mine to look like when i'm done with it ^_^

The ABS light stays on until you reach 5mph, it's more than likely a wheel sensor (air gap too large) try tapping them down one at a time then you may find the problem 1 which is an easy fix.

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It's more than likely an air gap on one of the wheel sensors, try tapping the sensor down one wheel at a time and trying the car this will point out which sensor it is (if that is the problem) the sensors are a push fit and when the wheel rotates it makes it's own air gap.

The bush that the sensor pushes in to becomes weak and allows the sensor to move, but I did an easy fix on mine.

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Hi just for clarification this how the warning light works

If all is OK the warning light will come on when you switch the ignition to position 2 , after two seconds it will go off for approx half a second and then come back on again and remain on until you drive forward and exceed 5 mph , it will then go out .

The system will "initially" check when powered up and tell you such. It'll run a check through the wiring, sensors etc and say all okay... during movement the system will check to see its getting speed signals ( voltage generation ) from the wheel sensors ie a voltage generated above 5 mph.

If the light remains on after driving forward you have a current and active fault with your system

If the light comes on any time you are driving you have just received a current and active fault .

The flash on/off and stay on again when stationary when just switching on confirms you currently have no stored faults in the ECU.

If it does NOT flash on and off but stays on you have a fault that is stored in the ABS ECU .

Then if the light then goes out when driving it is an old fault that has either corrected it self or been fixed by someone and the fault codes not cleared from the ECU or it is an intermittent fault.

If the light does not go out you have a current and active fault and you may not have full ABS operation.

I am 100 % sure of this as I have just spent a lot of time researching WABCO C ABS faults as I had a problem very recently on my Disco which I managed to fix .

Regards Jonathan

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another fault which can be hard to track is the support bearing in the hub assembly, this can wear leading to the cv joint moving up and down, giving a fault that says the sensor is playing up, or large air gap.

have tracked this one down on mine, after getting 14 fault codes iirc

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Well replaced the ECU (thanks for suggesting that :D) and apparently the front right wheel sensor has gone. I've posted in the 'wanted' part of the forums but its taking forever to be approved, so just wondering if anyone knows where I might be able to get one from?

Ta x

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Be carefull if you buy second hand sensors they can be damaged various ways during the removal process if not done carefully. A new one could be your best bet here. You can get them from most supliers on the internet for approx £65 to £95 Make sure you have cleared any codes in the ECU and get the warning light to flash correctly once , and take it for a test drive and double check what faults you get a couple of times, deleting them all before each test. Adam has the manufactures maintenance manual with all the fault codes so you should end up with one or two codes all pointing to the same sensor. The front sensors seem to get damaged more often than the rears , probably due to the steering exposing the wires to stretching( especially on cars with lifted suspension ) and off road hazards ie rocks and sticks. Regards Jonathan

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Hey,

Yeah checked the codes a few times, all points to that sensor, the wiring was damaged so stripped away the dead part but when testing the wires it was still open circuit so it needs a new sensor. Hopefully that will be all that's wrong :)

Adam

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