BMW Brake pressure sensors (E46 & others)

All sensor specific discussions! Temperature, pressure, steering angle, brake and throttle, etc. Post adaptations of OEM-style sensors, and also your clever DIY hacks and custom designs here too!

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smallspeed
Posts: 43
Joined: Mon Nov 30, 2015 1:08 pm
Location: Leicester, UK

BMW Brake pressure sensors (E46 & others)

Post by smallspeed »

Has anyone ever "mapped" a brake pressure sensor from the e46 m3 or similar? I believe these pressure sensors are used in all of the e46 era cars with DSC / ABS systems

I already have two in my mk60 ABS system (front/rear) but these do not output any data via CAN - I think they do output on some cars though, and they should be the same sensors..

I've managed to pick-up a couple of sensors cheap, and was planning on using them as analogue pressure sensors for RCP2, however am not sure what the output will be or what that will relate to (ie 0.5v - 4.5v equalling 0-250 bar or whatever). If I can't figure it out I'll keep them as spares and just use the brake light switch and TPS to indicate "coasting"

Hope someone can help

smallspeed
Posts: 43
Joined: Mon Nov 30, 2015 1:08 pm
Location: Leicester, UK

Post by smallspeed »

Circling back on this..
From what I can work out, the sensors read from 0.5-4.5v with a max 150bar
The signal is linear, so..

P = (V-0.5)*37.5

..or..

3.75bar per 0.1v

..or..

0.5v = 0bar
4.5v = 150bar

..depending how you’re programming it in
I don’t believe these poll over CAN so they’re purely available as an analogue signal if required
If I remembered my pins the correct way around..

PIN 1 - GND
PIN 2 - Signal
PIN 3 - +5v

brentp
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Post by brentp »

Hi, thanks for sharing this information. Are these the specs for the OEM sensor uses in the E46? They seem very similar to the standard 0.5 - 4.5 mapping you see with typical aftermarket sensors as well.
Brent Picasso
CEO and Founder, Autosport Labs
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