s13 sr20det VSS pulse output?

[NIZLAH]

Just a quick question that I cant find the answer to anywhere on the net...
Does anyone know the pulse type and per km output number of pulses an s13 sr20det speed sensor puts out?
Need it to help me calibrate my electronic speedo.

Cheers

Niz

[Skylar]

Japanese standard
637turns/1km
637rpm on 60km/h driving

Here a difference in the VSS senders
4 Magnets : Toyota,Honda, etc
2 Magnets : Nissan

4 Magnets (4 Pulse Car) : 39.25 cm/pulse
2 Magnets (2 Pulse Car) : 78.50 cm/pulse

[NIZLAH]

awesome.... cheers, so am I'm correct in thinking that it is an inductive sensor and one wire goes to the input of the speedo and the other is simply grounded yes?

Also would that make it pulse at twice the number of rotations due to the 2 magnets?
I think I have a problem still as the lowest pulse setting for my electric speedo is 3000....?

Do I need to find an alternate sensor for this set-up to work? ie a Toyota 4 magnet one that fits?

[Skylar]

Uhhh, I'm not quite sure about that. I think you can use it as an inductive, it has 32 pulses per rotation of the speed sensor. The sensor also shorts out the leads 4 times per rotation, so if you did ground it, you'd get 4 ground pulses per rotation with 5v or something provided by your speedo which. I tested that myself using a multimeter and a CRO. The stuff in the last post, I just found when googling 637rpm, I had that number in my head for speedo's but couldn't remember what it was.

[NIZLAH]

Ok well with my limited knowledge of electronics and this stuff in general, (I'm trying not to get confused lol) I was just assuming the s13 speed sensor was inductive since it only has two wires.. If grounding one wire does what you say, what do I do with it instead sine the speedo only has one terminal for a signal?
So the 637rpms of the sensor has nothing to do with how many times it pulses or does it? I meant does this number (637) get doubled as there is 2 magnets as you say and each pass of the magnet creates a pulse?

but going on from you last post, can I now assume that I multiply the 637rpms by the 32 pulses that it outputs per rotation?

would this then give me the pulse per km number I am looking for to calibrate?

[Skylar]

2 wires doesn't mean inductive, but it can be. Or it could be as simple as a reed switch and magnet configuration.

I think all you need is 637 x 32 to get you pulses per rpm if set in inductive mode. If it's set to voltage pulse mode then it'll be 637 x 4. See if there's any voltage on either of the two speedo sensor wires while engine running and stationary car.

BUT you'll need to correct the 637 by a factor of old(silvia) tire/new(corolla) tire * old diff ratio/new diff ratio.

[NIZLAH]

hmm, ok so does anyone else know if an s13 VSS is inductive ?

Skylar, all you input so far has been greatly appreciated, but I'm still somewhat confused on the calculation side of things...
ie: how do I correct the 637, my diff ratio is 4.7-4.8 and the tires are 235/65/15 (what ever that equates to in total rolling diameter?) haven't measured yet ...

[Skylar]

It IS inductive. I tested it on my oscilloscope. Voltage gets higher the faster you wind it and the pulses get closer obviously. BUT it also shorts out 4 times per rotation.

I'll go punch out some number on excel. Stock S13 is 4.1 diff?

[Skylar]

http://www.ae86drivingclub.com.au/dcimages/2/0/2/5/554186.jpg

[NIZLAH]

Most awesome you are mate . .
Is it safe to now assume that the magical number I need to program my speedo with is 8717?
Or have I missed something again lol..

Also does it matter which wire I use from the two as my signal wire? what do I do with the other wire left over if not grounding it?

appreciating all the help, I assure you, I apologize for my noobness on this subject

[Skylar]

What speedo is it? Instruction manual somewhere?

I don't wanna make the call on what to do with the other wire until I've read that. but earthing it would be safer than giving it power.

[Anthony]

2 wire pickup goes to speedo. speedo cluster then cleans it up and gives a low side pulse to the ecu. the ecu needs to have a "pullup" which the speedo grounds whenever it wants to pulse, making a square wave.

[Skylar]

I thought it was like that but I couldn't be bothered getting under my silvia to confirm. 5v pullup or 12v? Guessing it's 5v since processors are almost always 5v.

[Anthony]

yeah 5V usually covers it.

[NIZLAH]

speedo is a speco item...
The car is a Daihatsu Feroza with a Sr20det, never had a cluster so I'm not sure where the speedo sender wire is connected to, if anything?
Stock ECU also....

[NIZLAH]

http://www.speco.com.au/speedos.html

this is the model I am using.....

[Skylar]

Pretty shitty manual. and it isn't looking good for you.

they want a 5-17v in which is no problem but they want a 50% duty cycle which isn't what the nissan one does.

Hook the speed sensor up to 5v and ground, 12v should be fine for the voltage if you can't get 5v. Hook the speedo wire up to the 5v line that goes to the speed sensor and see if it works. According to the manual it won't. You might need the electronics out of a s13 speedo to do the signal conditioning and make it output a 5v square wave.

[NIZLAH]

hmm... that sux, sounds like a bit of dicking around if it doesn't wanna communicate straight off the speed sender.... oh well I plan to hook it up tomorrow so see how I go......

[NIZLAH]

Well to report back on my progress I hooked this up today, one wire to the signal input of the gauge and the other grounded....
it works, even after been dropped a meter onto concrete by the missus (wasn't impressed at all but we wont go there)
with 8717 as my base pulse count it was out by around 21%, the number I'm using now is around 10430, its still a little out, by 5-6kms, so still a bit of tweaking to do, but that is a tomorrow job....
Fairly pleased it was that easy...
Cheers for all the help gents...

[DX20VT]

637 is the standard calibration for cable driven speedo's and refers to the cable rotations per km.
RPM has nothing to do with electric speedo's.

sounds like you are onto it now anyway.

[Skylar]

haha, yeah, things never go to plan, no matter how much you calculate/figure it out. Theory says you'd need to put in the 70000 number to get it to work that way but it's much easier to just connect it up and correct using a gps.