VSS signal to ecu

This guy got 8500 ppm testing it on his bench. But it's an mk3 I think.

http://www.clubgti.com/showthread.php?259310-VSS-pulse-signal

:sigh: I'm getting exhausted trying to find this one piece of information. How are people able to adapt a non-VW VSS signal and not end up knowing what the VW VSS signal is?

I emailed ross-tech to see if anyone there can tell me. Andy emailed me back. I've got to get an auto-scan printout to him before we can move forward. Unfortunately I can't scan it till this afternoon so it'll probably be Monday before I hear back from them. I really hope someone there knows.

yeah the mkv uses the abs sensor data to determine road speed...no dedicated vss on these cars....

http://www.rostra.com/manuals/Form4428L.pdf

This form claims every VW from 1996-2009 uses an 8k ppm VSS.

rooney77 said:

http://www.rostra.com/manuals/Form4428L.pdf

This form claims every VW from 1996-2009 uses an 8k ppm VSS.

Click to expand...

that's the same company i got my info from via an install guide ... so is your jeep sensor a three wire ?

Yes it's a 3 wire.

Exciting update. At Andy's, from ross-tech, suggestion I tried recoding the distance multiplier to 3 and I'll be damned if it didn't work. Crazy since everything I've read says the mkiv has only two options (2 or 4) but I plugged it in, it accepted it and now I'm never more than 5mph off of where the math says I should be. Very happy camper. Andy, thank you again for the help.


edit: And thank you to you Jimbote for all your advice and willingness to help. I owe ya a beer for sure.

How do you go about doing that?

In vcds go to instruments, then coding. Should be a 5 digit number. The first two are for various equipment options, the 3rd is the country, the 4th digit is service interval and the last digit is your distance multiplier. Everything I've read says that the mkiv can only accept 2 or 4. Well that's obviously not the case. You just throw a 3 in there and see what happens. You can always change it back.

Cool I'll give it a try. Mine is about 20 miles slow right now

I'm not trying to discourage you but I was the exact opposite at 25mph fast. For all I know coding it to 3 may be a sort of reset and reevaluate type function. Give it a go and report back but by all means, write down what it was initially.

Okay, working with this on my 0a6 swap, this thread comes up on google with speedometer questions, may as well do it here.

02j has 22 teeth on the differential carrier and 13 teeth on the speedo pinion
using a sewing needle as a dowsing rod, the magnet that spins has 4 poles
so, 22/13*4= 6.77 pulses per axleshaft revolution

with 195/65/15s at a supposed 809 revs/mile that's something like 5476 pulses per mile. Call it 5500.

That may be double the proper number, as I don't know if the sensor is "seeing" both poles of the magnet, I don't know near enough about hall effect sensors. In fact I don't know if all 4 are N or S poles or alternating as I'd assumed. Oh well, thing's snapped back together and the screwdriver's outside.

A4 g/j/nb hub VSS is 43 teeth, which works out to 34787 pulses per mile with the same tires
6.35 times faster, dang, was hoping for something simple like 4x faster
5476/809= 6.77
so with a 7 toothed wheel at wheel speed I can get a close speedo signal. Almost right on (6.98) if I go to a 195/70/15

The ECU's VSS input is 1Hz per 1km/h, so 100km/h (62 mph) is a 100Hz, square wave signal. Some ECUs like 5V, all will safely take 12V.

Hasenwerk said:

The ECU's VSS input is 1Hz per 1km/h, so 100km/h (62 mph) is a 100Hz, square wave signal. Some ECUs like 5V, all will safely take 12V.

Click to expand...

Okay, so 60*60=3600 pulses per km
3600*1.61=5796 pulses per mile

So pretty dang close to my calculated number. Means that it triggers on all 4 poles of the magnet in the sensor. Thanks Hasen!

wired up a ford edge trans output speed sensor I found in the trash and made a 7 tooth wheel, heat-shrunk it onto the left inner CV and made a bracket out of angle iron, it reads proper.

calculations say 3% off with my current 195/65 tires, not too worried. Will go to 205/70/15 or 215/70 next time I find some in the junk tires pile at work, then it'll only read 1.1% off.