Brake Pad Sensor Light Won't Go Out

[cj10jeeper]

Late last week the worn pads light came up on the dash. Weekend in the Lakes is all I expected from the residual pad and it proved just enough

Replaced the rear pads today and know the front are almost new. Bit tricky getting the wear sensor in but all fitted.

Warning light now won't go out....

Anyone had any similar experience or logical reason for this, before I start a futile chase of disconnecting batttery and messing with both wheel sensors in the limited hope of finding something wrong.

 

[mmm-five]

I thought there was a OBC reset you had to do for brake sensors - but I could be wrong, as it's been about 2 years since I needed to replace pads.

 

[yg54sg]

Hi CJ, I had the same issue when i changed my pads, went out after driving around for a bit and a few re starts!

 

[Wondermike]

Maybe a stupid question :?

Did you use a new wear sensor, I thought if you triggered it you needed a new one?

 

[cj10jeeper]

mmm - can'r see any codes on a scan and not sure what I'd need to be resetting?

yg54sg - Not driven the car so will do that tomorrow and see if it goes out - good idea

Mike - no used the old sensor. Perhaps I need to change that in any event then. Not sure why unless it somehow creates an internal circuit in it. Previously I've always changed pads before tripping anything.

 

[EdButler]

Wear sensors are just an electrical circuit that breaks when worn through, no continuity throws the light, therefore you'll need a new one (don't know if you know this CJ!) All you need to do is bridge the connector to switch the light off in theory. The connectors are conveniently female so try just bending a paperclip and slotting it in.

I must say though, i have both of mine hacked like this (i can tell when my pads are dead thanks BMW!) and my light has popped back on, with no real reason. I was going to investigate soon.

 

[yg54sg]

You need a new wear sensor for sure, once the light comes on you have to throw them away

 

[srhutch]

beaten to it.

 

[yg54sg]

The reason you need to drive it after is because there is some kind of counting system it must use otherwise the light would flicker on/off as per Ed's description as its basically scraping the disc causing short circuit but by nature not 100% of the time. The light is solid so some computer must be monitoring the sensor then controlling the light. I can remember messing about driving around after putting a new sensor in, in the end the light went off by itself. Unfortunately I took the wheel off several times before I figured that out haha ..It likely waits for vehicle motion then no sensor contact within 5 minute of motion then resets the light something like that...

My rear pads need doing soon too... think they are still original! Going to replace the disc/drum at same time I think and hammerite the inner bits so they dont rust like the current ones!

 

[cj10jeeper]

Cool guys - good stuff to know. I was wrongly guessing that once the sensor touched the disc it triggered and would go out as soon as spaced away with the new pad. The avoidance of flicker logic makes great sense.

Frankly this is the first time I've ever activated one in a decade of BMW's so just filled in a gap in my knowledge

I'll get a sensor on order as the old one looks more than tired after 8 years on the car.

 

[Lance]

Ignition all the way on, but not started and wait for 45 seconds. Ignition off and then back on and all should be good.
Well that's what worked when my brake sensor light came on and I changed the pads.

Cheers
Lance

 

[pvr]

Sensors are £8 on eBay, plenty about. Once on they will never go off as the plastic has worn away to make the contact in the first place.

 

[cj10jeeper]

Sensors are £8 on eBay, plenty about. Once on they will never go off as the plastic has worn away to make the contact in the first place.

Thanks PVR - I'd ordered on within minutes of my post last night. £6 free post so cheaper than worth thinking about.

Will fit on receipt and no doubt cure the problem.

 

[Lance]

Sensors are £8 on eBay, plenty about. Once on they will never go off as the plastic has worn away to make the contact in the first place.

Thanks PVR - I'd ordered on within minutes of my post last night. £6 free post so cheaper than worth thinking about.

Will fit on receipt and no doubt cure the problem.

CJ, just out of curiosity, did you try to clear it with the ignition on (my post a few up).

I had the same problem when changing my pads and this sorted it.

Cheers

 

[cj10jeeper]

Sensors are £8 on eBay, plenty about. Once on they will never go off as the plastic has worn away to make the contact in the first place.

Thanks PVR - I'd ordered on within minutes of my post last night. £6 free post so cheaper than worth thinking about.

Will fit on receipt and no doubt cure the problem.

CJ, just out of curiosity, did you try to clear it with the ignition on (my post a few up).

I had the same problem when changing my pads and this sorted it.

Cheers

I had the ignition on for a long period (no engine running) and off and on, as I ran a diagnostics check on it anyway. Still showed.

Not driven it since yesterday but will do today

 

[ga41]

I agree with all above, once they trigger they need replacing. When you install your new ones the light will still be ON for a while (mine was for 2-3 days) and then go off by itself.

Lance, did you re-install the old one or new one? It is my understanding, as i mentioned ^, that once the sensor triggers then it's pretty much destroyed. I've wrecked two myself but that was due to my incompetence installing them....

 

[Lance]

GA, I re-used the old one.

I remember the problems with the light not going out and finding a thread via a google search, on bimmer somthing or other.

 

[ga41]

GA, I re-used the old one.

I remember the problems with the light not going out and finding a thread via a google search, on bimmer somthing or other.

That is odd! Everything i've read said that you needed new ones. Very interesting! It's not like i wait for the light to trigger to change mine but I'll keep that in mind for next time! I wear them out so quick (every about 8 months) that i swap them just to try different compounds.

 

[Lance]

I may of been a numpty here

Having thought more about this, when I changed the pads, it too was not triggered by the wear sensors so doesn't really apply here. DOH!

I drove over a bit of debris on the motorway when I first got the car and it pulled the sensor out of the pad, thus bringing up the light. I replaced the still untriggered sensor and it was at this point the light remained on. This is when I used the 'ignition on for 45 seconds' process.

Apologies if I've confused matters.

Lance