Wheel speed sensors

Discuss which Sensors work best with these ECUs and share how you are using inputs and outputs
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MGFMINI
Posts: 54
Joined: Thu May 05, 2016 6:39 am
ECU Model: P8 Pro
Location: Somerset, UK

Wheel speed sensors

Post by MGFMINI »

Good afternoon,
I have spent a few days messing about and learning how to use my scope and trying to get a decent wheel sensor output as could not get it right....
I have Rover MGTF reluctor rings which I have removed every other tooth to get the max number of pulses right to input into my DTA P8 Pro ( For traction control and launch) and also Race technology dash 2 for speed input.
I have done this with 4 x Siemens PA6.6-GF25 signal conditioners from an Astra which are 12v input, 0v , VR sensor in1 and in2 (that the MGTF VR ABS sensors are connected to) and a square wave output (To replicate hall effect sensor input as required by the DTA P8 ECU).

When I first tried it the best I could get was a very noisy less than 100mv output (Yellow = Square wave from conditioner @ 100mv scale) Green = VR sensor into conditioner @ 100mv scale) 100ms sample rate
Wheelspeed sensor 2.jpg
Which the dash would not run with (Not connected to ECU yet until I get it right, so not sure if it would work or not), so after a bit of swearing, messing and research I added a 1K Ohm pull up resistor which seemed to work really well, and reduced noise with a max voltage of 6.0 v, Thought I had cracked it as when I plugged the output into the dash it works fine (The dash accepts 12v max input...) Was pleased with the results as I am no electronics whizz by any stretch of the imagination. (Yellow = Square wave from conditioner @ 5v scale) Green = VR sensor into conditioner @ 100mv scale) 100ms sample rate.
Wheel  speed sensor 3.jpg
HOWEVER.....never that easy....when I disconnected and reconnected the signal converter (as powered by separate cable to the battery for now) the square wave output stays at 12v until the wheel is turned just enough for the VR sensor to see a tooth and thus triggering the signal conditioner and then it drops to 300mv approx between teeth and approx 3v peak, until the 12v feed is disconnected and reconnected...then 12v again.
As an experiment I added a small 12v led with resistor (Not sure what rating) from the output to 0v, to see if was a ghost voltage that would disappear with load, however it was not a ghost voltage but on the flip side it successfully drags down the output voltage to around 3v max and with the same scope profile. (The LED flashes every pulse, though dimly)
Siemens 1.png
Siemens 1.png (6.84 KiB) Viewed 5405 times
Bit concerned that if the led fails or the resistor burns out, the voltage may then go back to 12v until the wheel is turned......does anyone know if this will this damage the ECU input channel as they are 5v inputs, or if they are isolated?

Update-
I tried reducing the input voltage down to 6v with a couple resistors, and replace the LED with a diode (below) to the module and it seems to operate just as well so guess I could replace the two voltage dropping resistors with the 5v output from the ECU to power the module, and then just leave the pull up resistor and diode in circuit, as then the output voltage is limited to 5v, it is whether the ECU will see the square wave at 3v approx, any one have similar experiences or ideas?
Siemens 2.png
Thank you in advance
Alex DTA
Posts: 1622
Joined: Fri Feb 28, 2014 1:03 pm
ECU Model: S40 Pro
Distributor: DTA
Firmware Version: 79

Re: Wheel speed sensors

Post by Alex DTA »

I use those on my Audi. I don't know if the ABS sensors are the same.

I didn't use any pull ups.
I did have to join the ABS sensor ground to the ECU sensor ground to get the signal to work.

The ECU inputs are open collectors, so anywhere from 5v to 12v is fine. Not sure 3v will be enough, but it should be.
rocar
Posts: 107
Joined: Sat Sep 10, 2011 8:20 am

Re: Wheel speed sensors

Post by rocar »

Used Honeywell GT-101 Hall Effect Speed sensor with 12v and always works, now wired as Diagram with 5v but did not work ... Do these work with 5V ?
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Wheel speed sensors

Post by stevieturbo »

rocar wrote:Used Honeywell GT-101 Hall Effect Speed sensor with 12v and always works, now wired as Diagram with 5v but did not work ... Do these work with 5V ?
I've been using GT101's on my own car for some 18 years off 5v with no problems. Both with the DTA P8, S80 and now the Syvecs.

Although I also see the GT101's have been discontinued.
SMR
Posts: 137
Joined: Tue Jan 16, 2018 9:38 am
ECU Model: S100 Pro
Distributor: DTA
Location: Aberdeen

Re: Wheel speed sensors

Post by SMR »

I've always used the GT101 sensors with the 5v from the S100 with no problems.
rocar
Posts: 107
Joined: Sat Sep 10, 2011 8:20 am

Re: Wheel speed sensors

Post by rocar »

Worked.. wrong wire position :lol:
Yes Stevie seems they are discontinued.
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Wheel speed sensors

Post by stevieturbo »

rocar wrote:Worked.. wrong wire position :lol:
Yes Stevie seems they are discontinued.
I've done that before too lol.
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