Forum » General Tuning Discussion » Connecting a VSS

Connecting a VSS

General Tuning Discussion

Discuss all things tuning in this section. News, products, problems and results. 

Page 1

Ok so was setting up Launch Control in a E36 BMW that I had fitted a RB25DET to and wanted the VSS input going into the Haltech.

The car standard has a VSS on the diff and this is currently running the Dash cluster, There is also a 2-wire VSS on the R33 gearbox... I was not sure what type of sensors these are so I tried feeding 12V to it and connecting the other side to the Haltech DPI but no signal.

So after abit of research it seems the R33 VSS being a 2-wire would be a reluctor pickup? is this correct?

And seems the Haltech needs a square wave input?

The stock diff VSS is also a 2 wire.

What are my options here, Is there a converter box to convert a reluctor signal to square wave?

I believe the ABS sensors are Hall Effect... Am I able to piggyback off one of these sensors, will they mess with the ABS system / give false readings?

Would there be anywhere in the factory loom as a part of the speedo that has a squarewave output I can connect to or would it just natively use the Sine wave from the stock VSS?

MoTeC makes a small adapter that can produce a square wave from a mag sensor (it can handle two signals in one converter). Look at the DMC D found near the bottom of this page:

reluctor interface:

Maxim MAX9924/6

And before you ask, being more into the DIY side, yes that's just an electronic component.

take a look at Dakota Digital Products:

from what I know, the Nissan SR20DET guys use this device a lot.

I personally was able using the backplane of the stock S14 200SX speedo (just the speedometer part), to get the VSS signal working with a PS2000 Haltech.

Without hooking up that backplane, the Haltech didn't get any useful signal.

anyways, maybe worth a try.

As a general guide, if you are looking at a two terminal sensor then it is going to be a reluctor/magnetic sensor. Hall requires three wires. I've yet to fit a speed sensor to a Haltech so can't really comment too much further. As others have already posted though, there are a number of ways of getting a square wave digital signal from an reluctor sensor.

ABS wheel speed sensors are also in my experience usually a reluctor sensor, but the high tooth count can pose a problem for many ECUs as the frequency can become too high for them to read. If you are retaining the ABS functionality then trying to hijack the signal is not advisable. In the past on cars where the ABS has been removed, I've removed teeth from the sensor ring to reduce the tooth count to something more sensible and this has worked well for me.