How To: VSS signal from FC (MS3X)
 

Hi everyone,

I've been busy setting up my MS3Xv3.0 on my JimStim and getting ready to wire it up this winter.
I really wanted to use all of the fancy features that MS3X has that my previous MS2 didn't.
Particularly, boost-by-gear and eventually traction (requires a second VSS).

I found that the VSS signal is extremely easy to source from the stock gauge cluster.
The stock cluster outputs a pulsed 12V signal for the cruise control.
I chose to use the N2O IN wire (pin 29) because it is designed to take 12V. Other inputs may work fine, but I played it safe and only used what I knew was rated for the voltage.

Disclaimer: Perform at your own risk. These values and methods worked for me, but your experience may vary.


The wire you want to use for the VSS is the Green w/ Red striped wire from the back of the cluster. It can also be found in the driver side kick panel (instructions can be found HERE)

I plan to retain the factory cruise control, so I'm going to tee into the VSS wire and hope cruise still works. I had cruise working great with my MS2 setup and really want to keep it functional. Ill let everyone know how that works in the future.

I then set up the VSS in Advanced Engine > Speed and Gear Sensors > Vehicle Speed Sensor 1
See attached for settings.
These will have to be tuned to your specific car and should be set to a GPS speed, but these numbers should get you close.
To tune the VSS accuracy, increase the pulse-per-mile to lower the VSS value, or decrease the pulse-per-mile to increase the VSS value.
The values I've provided worked well enough using a drill and spinning the cluster to 60mph.


Hope this helps anyone wanting to incorporate VSS for their MS3X.
I will update this thread when I have a second VSS working. I'm planning on adding a Hall sensor behind the wheel studs on a front wheel and using PT4 as the input. I've heard great things about MS3's traction control and hope to have it implemented soon!

Should have no problem sharing the VSS signal with the 'Squirt and the cruise. The 'Squirt input is pretty high impedance and since the signal is 12V, it can drive a bit of load.

this is good to know. as I have just received my hall effect sensor. was going to make bracket and have it looking at a trigger on drive shaft. now with this adding this also I'll have a second easy input. brilliant.

You may want to reconsider locating it on the driveshaft. The VSS from the speedo is basically driveshaft speed. If you get wheel spin, both sensors will climb. You'd be better mounting the sensor behind the lug bolts on a front hub, basically where the dust shield is. This will allow you to capture front AND rear wheel speed to calculate slip. Cherry has some nice and inexpensive Hall sensors that have an entirely threaded body to allow you to easily set sensor spacing with jam nuts.

I see. that makes sense. do the clusters in non cruise control equipped cars still have a pulsed output?

I believe it should work just fine. There's no mention of different wiring for cruise and non-cruise differences in the wiring diagram. When they are different, the diagram will show an asterisk or other characters to denote a deviation, like for turbo/non-turbo or convertible.

This is what I did, but it's not that simple for an FC cast aluminum hub. Luckily I had access to a CNC mill at the time I did mine.

Attachment 617039

Attachment 617040

Attachment 617041

Thanks! Hopefully I can cut and ground mine out without having to take them to a machine shop.

You could use an FC hub with the ABS tone ring. That's my plan for a speed signal to the MS3-Pro on my Cosmo. Bolts right on.

I posted a WTB add in the Parts FS section for a ABS knuckle but so far no one has offered one up. If anyone has an ABS knuckle for sale, let me know! Doesn't matter which side.

I got to help tune a 500whp turbo E30 last weekend that we added MS3X traction control. It is impressive to say the least. With traction off, the car would spin the tires in 3rd on good pavement. With it on, first gear was sputtery but still faster than spinning, second gear hooked like crazy and 3rd was awesome. We only spend a few minutes setting it up and adding VSS from the diff and front knuckle. Definitely worth the effort!

Might want to try a WTB in the Canadian forum. Loads of FCs over here were ABS equipped.

Cool to see someone doing this. glad they are using a good control strategy that works with out to much effort.

AAron, I'm sure you're well aware, but the frequency of an ABS ring is much greater than most of the inputs allow. The only true high frequency input is PT4 which should be fine if you're just using one VSS on an ABS ring.

I believe you can also use the Cam sensor inputs on the MS3X board if you're using a trigger wheel like me. The FFE trigger only uses the Crank speed input on the mainboard so I could potentially use both CAM and PT4.

above is what I am aiming to do with the 36-1 ffe trigger and inputs so can use abs ring.

If you use the Nitrous input and the speedo output from my first post, you will have almost the exact resolution using the 5 lug sensors. The Nitrous input wouldn't max out until around 180 mph at 200Hz. The ABS sensor would really only have an advantage if you were using it for the front and rear and I'm honestly not even sure it would have an advantage over 5 pulses per rev. The BMW we tuned had a 9 pulse-per-rev factory sensor and a 40-something tooth ABS ring at the front. It didn't have much problem hooking up in first with traction control enabled. I believe the slip threshold was set to 5%.

How To: VSS signal from FC (MS3X)
 

I agree that the abs ring is probably a to fine a resolution but the above pictures of machining the hub gussets off seems a big potential sacrifice to give the sensor a good readable surface. possibly the abs ring and remove every so many triggers? havnt seen the abs count so would have to be what ever divides equally.

The bosses that were machined off are for mounting the abs ring on the backside and extra depth for the screws that hold the rotor to the hub. Nothing that was removed was there for strength. Also, I finished the cut with a ball nose end mill to ensure there were no stress risers at the inside corner.

Remove the extra teeth.

What pin would this be on an MS3 Pro?

Any of the frequency inputs. I was wrong earlier about the frequency being too great- ms3pro frequency inputs can accept pretty high frequency. However, if you use a 2 wire VR sensor, you'll need a conditioner circuit.

The cruise control VSS is square wave 12V. Use the Nitrous IN for the cluster VSS. I'm using the CAM IN circuit or my ABS sensor since it can condition a VR IN. The rest of the high speed ins are 5V square wave. JBPerf sells a small digital converter for a fair price that I've seen people have good luck with. My ABS sensor worked great on the first shot.

There is no "Nitrous In" on the MS3-Pro. I'm looking for the right input to use for the cruise VSS. Would it be "Digital Frequency In x" ?

http://www.ms3pro.com/_downloads/ms3pro_wiring_web.pdf

On the MS3-Pro you can use any of the digital frequency in lines. However, if the speed sensor is a VR sensor like the FC ABS sensor, then you need a conditioning circuit (LM1815will work) to transform the variable voltage sine wave into a square wave.

Aaron, are the digitial ins on the MS3-Pro capable of seeing 12V? I was under the assumption that they were 0-5V only.