How does the brake pad wear sensor work?

jvictormp · 07-14-2020, 05:50 AM

Hi guys.

Would you know how the brake pad wear sensor work?

I mean, when it's normal, is there a constant current passing through it, that decreases or increases as the wear goes on?

If the two sensor wires contact each other, will it damage the electronic module?

Dpc2u · 07-14-2020, 06:37 AM

It works by measuring resistance.It is a dual stage, so there are 2 wires in the sensor that when worn through, change the resistance values. That makes it a 2 stage warning of wear indication.

jvictormp · 07-14-2020, 07:41 AM

Thanks.

Will it damage the module if I connect the two wires of the sensor?

Dpc2u · 07-14-2020, 07:48 AM

Quote:

Originally Posted by jvictormp

Thanks.

Will it damage the module if I connect the two wires of the sensor?

No, it will not damage it. It will fool it into thinking it has full resistance. If it is already showing a brake warning, you will have to do a reset procedure though. Do a search. I can't remember the steps, haven't done it in quite a while.

tdott · 07-14-2020, 08:13 AM

Quote:

Originally Posted by jvictormp

Thanks.

Will it damage the module if I connect the two wires of the sensor?

No, I have old sensors that I cut the wires off and bridge together. I use them when I have my track pads in, since they don't have slots for the sensors and they would probably melt at the track.

jvictormp · 07-14-2020, 08:39 AM

Nice, thanks for the answers!

SAMM3Y · 07-14-2020, 09:08 AM

Quote:

Originally Posted by Dpc2u

Quote:

Originally Posted by jvictormp

Thanks.

Will it damage the module if I connect the two wires of the sensor?

No, it will not damage it. It will fool it into thinking it has full resistance. If it is already showing a brake warning, you will have to do a reset procedure though. Do a search. I can't remember the steps, haven't done it in quite a while.

Technically it'll have no resistance, you're shorting it. I'd recommend doing it way back
By the connector to keep them out the way.

jvictormp · 07-14-2020, 08:22 PM

Quote:

Originally Posted by SAMM3Y

Technically it'll have no resistance, you're shorting it. I'd recommend doing it way back
By the connector to keep them out the way.

In that case, I would need to know what's the resistance of the sensor with no wear indication.

Dpc2u · 07-14-2020, 08:42 PM

I believe it is about 2000 ohms as I recall. If you are thinking that you need to add a resistor, you don't. Just connect the two wires together to complete the circuit. I personally just spring for new sensors, but have done the cheat to get me by in a jam. You may be overthinking it.

jvictormp · 07-14-2020, 08:49 PM

I'm doing it. Thanks!

roastbeef · 07-14-2020, 08:50 PM

This is how it should look. Nice and short.

derbo · 07-14-2020, 08:53 PM

Quote:

Originally Posted by roastbeef

This is how it should look. Nice and short.

I did similar.

View post on imgur.com

SAMM3Y · 07-14-2020, 09:06 PM

Quote:

Originally Posted by jvictormp

Quote:

Originally Posted by SAMM3Y

Technically it'll have no resistance, you're shorting it. I'd recommend doing it way back
By the connector to keep them out the way.

In that case, I would need to know what's the resistance of the sensor with no wear indication.

0 ohms

Bartledoo · 07-24-2020, 10:53 PM

Quote:

Originally Posted by SAMM3Y

0 ohms

I found some info somewhere that indicated it was below 1ohm but greater than zero. Resetting after crossing the wires wouldn't give me anywhere near the full mileage. Perhaps having a lower resistance than new causes this? I'll order some new ones to check at some point unless somebody else already has...

SAMM3Y · 07-25-2020, 12:26 AM

Quote:

Originally Posted by Bartledoo

Quote:

Originally Posted by SAMM3Y

0 ohms

I found some info somewhere that indicated it was below 1ohm but greater than zero. Resetting after crossing the wires wouldn't give me anywhere near the full mileage. Perhaps having a lower resistance than new causes this? I'll order some new ones to check at some point unless somebody else already has...

Pretty sure I cut one open and it was just a thin copper strand that once broken through wear started a count down with the car... can't recall though it was a few years and beers ago. Any resistance would cause heat and load and it's encased in plastic. Anything less than an ohm is a closed loop your meter is just picking up a little resistance from your probes.

Dpc2u · 07-25-2020, 05:49 AM

This-

https://www.newtis.info/tisv2/a/en/f...-right/WzRZydX

And this-

https://www.e90post.com/forums/showthread.php?t=981050

We have 2 stage sensors with a resistor.

SAMM3Y · 07-25-2020, 01:10 PM

Quote:

Originally Posted by Dpc2u

This-

https://www.newtis.info/tisv2/a/en/f...-right/WzRZydX

And this-

https://www.e90post.com/forums/showthread.php?t=981050

We have 2 stage sensors with a resistor.

Trust bmw to overengineer it.. I must be thinking of another brand

07-14-2020, 05:50 AM	#1
jvictormp Captain 881 Rep 787 Posts Drives: 2008 M3 E92 6MT Join Date: Dec 2018 Location: Brazil iTrader: (0)	How does the brake pad wear sensor work? Hi guys. Would you know how the brake pad wear sensor work? I mean, when it's normal, is there a constant current passing through it, that decreases or increases as the wear goes on? If the two sensor wires contact each other, will it damage the electronic module?
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07-14-2020, 06:37 AM	#2
Dpc2u Major 11503 Rep 1,069 Posts Drives: E93 M3, E60 M5, F15 X5, E46 Join Date: Feb 2019 Location: Middle Tennessee iTrader: (0)	It works by measuring resistance.It is a dual stage, so there are 2 wires in the sensor that when worn through, change the resistance values. That makes it a 2 stage warning of wear indication. __________________ E46, E60 M5, E93 M3, F15 X5 IG - @thebimmerhaus
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07-14-2020, 07:41 AM	#3
jvictormp Captain 881 Rep 787 Posts Drives: 2008 M3 E92 6MT Join Date: Dec 2018 Location: Brazil iTrader: (0)	Thanks. Will it damage the module if I connect the two wires of the sensor?
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07-14-2020, 08:39 AM	#6
jvictormp Captain 881 Rep 787 Posts Drives: 2008 M3 E92 6MT Join Date: Dec 2018 Location: Brazil iTrader: (0)	Nice, thanks for the answers!
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07-14-2020, 08:42 PM	#9
Dpc2u Major 11503 Rep 1,069 Posts Drives: E93 M3, E60 M5, F15 X5, E46 Join Date: Feb 2019 Location: Middle Tennessee iTrader: (0)	I believe it is about 2000 ohms as I recall. If you are thinking that you need to add a resistor, you don't. Just connect the two wires together to complete the circuit. I personally just spring for new sensors, but have done the cheat to get me by in a jam. You may be overthinking it. __________________ E46, E60 M5, E93 M3, F15 X5 IG - @thebimmerhaus
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07-14-2020, 08:49 PM	#10
jvictormp Captain 881 Rep 787 Posts Drives: 2008 M3 E92 6MT Join Date: Dec 2018 Location: Brazil iTrader: (0)	I'm doing it. Thanks!
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07-14-2020, 08:50 PM	#11
roastbeef Lieutenant General 11585 Rep 12,724 Posts Drives: E92 M3 Join Date: Nov 2010 Location: Orange County, CA iTrader: (4)	This is how it should look. Nice and short. Attached Images __________________ Instagram; @roastbeefmike
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07-25-2020, 05:49 AM	#16
Dpc2u Major 11503 Rep 1,069 Posts Drives: E93 M3, E60 M5, F15 X5, E46 Join Date: Feb 2019 Location: Middle Tennessee iTrader: (0)	This- https://www.newtis.info/tisv2/a/en/f...-right/WzRZydX And this- https://www.e90post.com/forums/showthread.php?t=981050 We have 2 stage sensors with a resistor. __________________ E46, E60 M5, E93 M3, F15 X5 IG - @thebimmerhaus
	Appreciate 3 Bartledoo2691.50 SAMM3Y3085.00 jvictormp881.00 Quote