faulty sensors or faulty car?

[sadexpunk]

57 octavia L&K.  for some months now, the brake pad warning light comes on intermittently to show low pads.  then next time i switch on its not there.  had it looked at whilst being MOT'd and garage said faulty sensor, they could weld it up or something to stop it coming on, but then itd never show if i actually did have low pads.  i may take them up on that.

 

however, for the last week, the warning lights for ABS and the 'sliding car' light are usually lit up.  sometimes just ABS for a few seconds then both.  sometimes one will go off again then back on, but theyre both on pretty much 100% now whilst driving.

 

so....... is it likely to be faulty sensors, or will the ABS actually not be working?

 

thanks

[satire111]

The low pad wear sensor is completely independent from the abs system when the abs system light is on it may well be a problem with a sensor but the sensors for the abs system are on all four wheels the sensor for the front brake pad sensor is on the front left hand pad only

hope this helps 

[CWARD]

Probably the ABS ring on the hub that's corroded or broken.

[sadexpunk]

4 hours ago, satire111 said:

The low pad wear sensor is completely independent from the abs system when the abs system light is on it may well be a problem with a sensor but the sensors for the abs system are on all four wheels the sensor for the front brake pad sensor is on the front left hand pad only

hope this helps 

 

thanks, so its probably going to be fine to get that welded up then.

 

4 hours ago, CWARD said:

Probably the ABS ring on the hub that's corroded or broken.

 

sorry, im not very technically minded and dont understand car mechanics.  is that a problem with the ABS itself or just faulty sensors then?  and assuming youre right, whats my best course of action?

 

thanks

[CWARD]

It's the ring that goes inside the hub. The ring has holes in it so as it passes under the sensor it can be measured. The rings on these cars tend to corrode and break. I think it's a case of replacing the hub if that's the case. 

If you get the car scanned for faults it should tell you which corner is at fault. If you swap the sensors over from one a good wheel to the faulty corner it will confirm it's the ring if the fault stays in the same position. 

Edited 4 October, 2017 by CWARD

[CWARD]

The pad wear sensors are replaceable. They simply clip into one of the inside pads and plug into the wiring under the wheel arch. Usually just one pad sensor at the front and one at the rear. 

[CWARD]

This video is on a VW but same system 

 

https://m.youtube.com/watch?v=6C4bFzSw_zg

[sadexpunk]

thank you very much, ill have a word with my mate who has a diagnostics system, see if i can get to the bottom of it.

 

cheers

[sadexpunk]

had a mate with diagnostics look at it for me and has confirmed that its the rear right wheel, however he says the diagnostics dont say whether its the ring or the sensor.  as i mentioned before, im not technically minded so id be getting someone else to do it for me, but may be able to save money by buying the part(s) first.

 

could anyone point me in the direction of the parts id need, the ring and/or sensor please?  is ebay my best bet?  

 

thanks a lot

[CWARD]

I think but not sure that the ABS ring is built into the wheel bearing assembly so would need to replace the whole wheel bearing.  The sensor is just screwed into the back of the hub as per the picture below.

 

 

If you unclip the wire that goes into this and unscrew (only one screw to remove) the sensor and swap it with the left rear one. If the fault moves to the left rear wheel it is the sensor that is at fault otherwise it is the ABS ring and a new wheel bearing assembly is required.  

 

If it is the sensor then these are what you need  you can get them cheaper but having bought cheap previously they don't tend to last so get Bosch or Ate ones.

[CWARD]

This video shows you how to remove the sensor, although they manage to butcher it. if you give a squirt of WD40 first then once you've remove the screw give it a little twist back and forth they should just pull straight out without breaking.

 

[sadexpunk]

thank you mate.  before i start fiddling about, im told that if the lights on all the time its likely to be the sensor, if it only comes on when i go above 5mph, then itll be the ring.  mine is the second case, so is it almost certainly the ring then?

 

thanks

[CWARD]

I couldn't say. I thought they were dependent on each other and if either failed you would get the same fault. If you take the sensor out and rotate the wheel and looking down the hole the sensor mounts into you will see the ABS ring inside the hub if it is badly corroded or broken you will see this. Problem being that you will need some torch, mirror or use your phone camera to get the angle to do this.  

Edited 18 October, 2017 by CWARD