G68 - Vehicle Speed Sensor Info please

[UrS4boy]

G22/G68 Vehicle Speed Sensor info

Updated my VSS post to include all the new info from today:

http://forums.quattroworld.com/s4s6/msgs/168463.phtml

[UrS4boy]

Can anyone tell me some info about the G68 vehicle speed sensor?Thanks. Alex

Hmmm....I thought "G68" was the B3/B4 S2/RS2 version of the "G22" C4 UrS vehicle speed sensor. However, in trying to confirm the G68, I just found some S2 wiring diagrams that refer to the sensor as "G22". Why are you calling it the G68? (Reference diagram??)

[johne]

Can anyone confirm then that the sender in the OEM system / configuration generates a 5v square wave pulse as Aaron's description above?

The sender doesn't generate anything as such. It's connected directly to the speedo chip (UAF2115) which provides a current source of approx. 5mA using a pnp transistor (aka Aaron's 1K resistor) which the reed switch sinks to ground.

John

[terrybullwon]

I got your Pm Alex but am at work, I have such system working on my Dash let me know what your trying to do

[Error404]

Hmmm....I thought "G68" was the B3/B4 S2/RS2 version of the "G22" C4 UrS vehicle speed sensor. However, in trying to confirm the G68, I just found some S2 wiring diagrams that refer to the sensor as "G22". Why are you calling it the G68? (Reference diagram??)

Can't say to be honest, I just thought that's what it was referred to as from reading other threads and the web etc.

johne I sent you a PM

[UrS4boy]

Can't say to be honest, I just thought that's what it was referred to as from reading other threads and the web etc.

Okay, fair enough. I just Googled "g68 speed sensor". Comes back with VW and Skoda references, not Audi. I am going to stick with G22 on that basis.

[driftin jo]

Okay, fair enough. I just Googled "g68 speed sensor". Comes back with VW and Skoda references, not Audi. I am going to stick with G22 on that basis.

It would seem that this has come from the fact that VAG-COM reports it as G68.
See thread.

http://www.s2forum.com/forum/showthread.php?t=28273

[UrS4boy]

It would seem that this has come from the fact that VAG-COM reports it as G68. See thread.
http://www.s2forum.com/forum/showthread.php?t=28273

Thanks.

That kind of makes sense in that VWs use "G68" for the VSS. It is stilll a "G22" for our cars.

[4WheelDrifter]

The sensor is definitely a simple reed switch. It just hangs in the tip of the plastic body on a length of cable. I am pretty sure I posted a photo somewhere, when I took one apart.
The ring on the output shaft is magnetic, as what was left of it had loads of shrapnel stuck to it in my old gearbox.

You can spin the wheel and get a pulse.

[edge_devil]

The sender doesn't generate anything as such. It's connected directly to the speedo chip (UAF2115) which provides a current source of approx. 5mA using a pnp transistor (aka Aaron's 1K resistor) which the reed switch sinks to ground.

John

Hiya John,

I was reading your post and thought you might have some extra information around the UAF2115....

I have the G22 signal output connected direct to the ECU. So you think this should work, or do I need to create a trigger circuit for the G22 signal to be turned into a clean square wave for the ECU?

Ta mucho!!

[S2central.net]

I am pretty sure it is four pulses per rotation - eight edges if you like to think that way.

[edge_devil]

I am pretty sure it is four pulses per rotation - eight edges if you like to think that way.

Hi Paul,

Yes that's what I measured on the sensor, but I think I need to amplify the G22 signal if it is going direct to the ECU... well according to your other post

[UrS4boy]

I am pretty sure it is four pulses per rotation - eight edges if you like to think that way.

http://forums.quattroworld.com/s4s6/msgs/168463.phtml

[edge_devil]

...but it's what the UAF2115 does to it that interests me.... The number of pulses is not a matter of debate any more as it is easy to measure, but the VSS from the speedo to the ECU I can't figure out.

I'm worried that the reed signal format, pulse length etc is modified by the UAF2115 in the back of the speedo housing before being sent out to the ECU.

[dustovich]

Look on page 2 of this post. I did some testing personally on my Urs4 with my multimeter. Use the later posts, I had to correct some errors and did not have editing privileges at the time. I believe I was measuring the output of the gauge cluster, at the red connector in connector station 2. I tried putting my meter on the actual device on my spare tranny and did not get any output, but I could have been measuring incorrectly at the time (i think voltage instead of ohms) assuming it was a hall sender vs a reed switch.
http://forums.audiworld.com/showthread.php?t=2834884