FuryX - Crank & Cam Hall Trigger +8v Feed? Pullup?

[jgoddard91]

Hi All,

Im fitting a Hall effect cherry / ZF sensor for both my crank input (36-2) and my cam input - 1x. Being a Hall sensor I would need a stable +ve supply (assuming from the ECU) , a sensor ground (supplied on ECU pin 7) and the respective Crank & Cam signals (ECU pins 8 & 9).

I assume my +ve feed will have to come from the ECU (refered to as "VCC" in my sensor technial data)... (not just my 12v master live) thus i would utilise the +8v feed on ECU pin 6...???

If this was the case, the pull up resistor would have to be ~ 1.6k ohms. How do I know the pullup resistor value within the ECU? or is the resistor value not too much of a concern and will work aslong as the pullup resistor is present?

My Cam sensor is actually asking for "+12v Filtered from ECU"... so im a little confused, but i dont yet have a datasheet for this... Any help would be much appreciated..

All the best,

Jamie

 

[Adamw]

Yeah the 8V pin will be fine for both.  The internal pull-up is 4.7K so for the crank sensor it would be good insurance to turn off the internal one and fit the recommended value externally.   Although the ZF sensors are usually ok with the internal pull-up for up to about 36T, I have seen them give problems with 60 tooth wheels with the weaker internal pull-up.  The cam sensor will be fine with the internal pull-up.   

[jgoddard91]

Okay perfect!

So I can just disable the pullup for both triggers, fit one 1.6k resistor from the 8v ecu out, then split off into 2x 8v feeds @ 1.6k and she'll be by the book?

Thanks for the clarification.

Just out of curiosity, what is the fundamental function of a pullup resistor? Why does a hall sensor require it? Would you see something different on the trigger scope with the wrong resistor fitted?