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Re: Wheel speed sensor questions

Posted: Wed Sep 14, 2011 1:21 am
by mefmotorsport
Jon K wrote:
stevieturbo wrote:
Jon K wrote:Hall sensor doesn't actually give out any power. Some hall sensors can handle 4.5 - 24vdc. You need to look at the spec for your given sensor. The output is a "sinking" output that closes. The DTA actually supplies the "voltage" for the incoming signal because there is a 1K ohm pull-up resistor to 5v internally on the ECU.
So does the sensor actually ground the "signal" line upon a pulse ?
Yep - on a sinking sensor the output is open, so the CPU inside the DTA sees the high signal (5v with 1K ohm pull up). When a pulse comes out (tooth present) of the sensor, it pulls that 5v down to 0v and the 1K ohm resistor limits current to the "short" to ground.

Matthud - be careful, the DTA won't like that. It has an internal pull up. I imagine if you put 12v into the DTA wheel speed input you'd be back-feeding the 5V power supply circuit with 12V

You could put a diode in series to stop it back feeding, it depends if the dta is OK with the residual 0.6v that would exist when the sensor pulls the diode down to ground. Worth a try.
Image
Martin

Re: Wheel speed sensor questions

Posted: Thu Mar 22, 2012 9:36 am
by tzei
uhum... as in S60's wiring schematics speed signal comes from a hall sensor i.e. honeywell igt101dc (3 wires) so signal is 5v to nothing correct?

Has anyone used cars own speed sensor - can it be make to work? My case question is about BMW's oem sensor fitted in diff casing. Two wires and it cuts ground to oem speedometer. I have used this sensor/signal for Apex AVC-R. ECU does not understand this signal right?

I quess i could send this signal straight to AIM mxl pista dash but then again am i in for a trouble when i'm going to put ECU to communicate (via CAN) with dash?

Re: Wheel speed sensor questions

Posted: Thu Mar 22, 2012 12:26 pm
by Jon K
We use the BMW sensors with the VR to Hall converter boards. They work very well. The diff could be used too, but you might as well use the wheel speed vs the diff because it will be an undriven wheel instead of driven - traction will dictate the road speed if referencing the diff/rear wheels.

Re: Wheel speed sensor questions

Posted: Thu Mar 22, 2012 2:18 pm
by stevieturbo
Dual channel converter

http://jbperf.com/dual_VR/v2_0.html

Or Jaycar make a little speed signal adjuster kit. I think it can take any type of signal and convert it's output to digital, although it is only a single channel and mainly intended to multiply or divide the pulses

http://www.jaycarelectronics.co.uk/prod ... rm=KEYWORD