Automotive Crankshaft Hall Sensors

Thread Starter

GoStags

Joined Feb 10, 2024
6
A bit of reverse engineering! I have bought a couple of different Crankshaft sensors (BMW types) which have 3 pins, and which I believe to be Hall sensors. They have a built-in magnet, and are supposed to output a digital signal with frequency proportional to the change in magnetic field strength from a toothed steel wheel.

I want to interface these with an engine ECU that can receive the digital signal, of 5volts or 12 volts.

Not having or being able to find any info on the pin designation, I have tried all combinations to identify the correct one to get a digital output to no avail. The 3 pins are supposed to be as follows: Power, Ground and signal. I have also tried using a pull-up resistor in case the output is 'open collector' to no avail. When placing a piece of steel to it, I can get a small response from one sensor where one wire changes state between 0.7 volts and 0.1 volts approx but cant get at least 5 volts by any means.

For those not familiar with automotive digital hall sensors they comprise a permanent magnet, a hall sensor, followed by a high gain amplifier, then a Schmitt trigger at the output.

Have I missed something in my attempt to get an output?
 

geekoftheweek

Joined Oct 6, 2013
1,221
Normally three wires is a good indication of a Hall type trigger. While most of the time automotive sensors are built tough enough to withstand reverse connections and such it is possible you may have damaged it trying to figure it out.

Judging from the links you are not in the US so maybe you have access to different materials, but usually Mitchel (https://eautorepair.net) has good wiring diagrams, pinout information, and general how it works. It's going to cost a little bit which may be a deal breaker, or it may not even be available where you are. I just know it has saved me a lot of time and headaches.

Other than that the best thing to do is either find a wiring diagram or a working car that you can use to probe the connector and find out.
 

MaxHeadRoom

Joined Jul 18, 2013
28,698
They appear almost identical to the Honeywell 1GT101DC, after market drop-in for the automotive flywheel (ferrous metal/gear tooth) sensor.
These are Sink mode output.

1707581673044.png
 

LowQCab

Joined Nov 6, 2012
4,075
Evidently the Sensor in question is not going in to a BMW-Engine.

Are General-Motors-Parts available in your area ?,
they are user-friendly, cheap, and well documented.

It's possible that You have smoked the Sensor that You have by applying Power in reverse,
this may completely destroy the Sensor instantaneously.
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.
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MaxHeadRoom

Joined Jul 18, 2013
28,698
If these are used for experimenting, a local auto wrecker is one place to source them.
We have one that allows 'strip-it-yourself'. !
 

Thread Starter

GoStags

Joined Feb 10, 2024
6
If anyone knows of any gear tooth crankshaft Hall Sensor, UK stock, that comes with a data sheet please let me know.
 

MaxHeadRoom

Joined Jul 18, 2013
28,698
If you get hold of one that has leads attached, the colour of each may be a clue, for e.g. the Honeywell it is Red, Blk for power, & white for the signal wire, also it has reverse polarity protection built in.
 
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