Vehicle Speed Sensor Question

[fliprayzin240sx]

What makes them operate? I know the VSS has a plastic gear on it, does that physically touch something in the tranny or does the transmission fluid pressure somehow spin it? Reason im asking is ive been having issues with my Silvia. When its cold, my speedo doesnt work. After driving it for a bit, the speedo starts picking up and starts working again. Im guessing this has something to do with the tranny temp. If it has something to do with fluid, would having low gear oil be a culprit for this phenomenon? It didnt bother me till after I changed my clutch today. I literally had to drive close to 30 km before it started working again. Like the gear took that long to unstuck itself or something.

[g6civcx]

Most Nissan Vehicle Speed Sensors(s) are gear driven. Th VSS itself has a plastic gear that gets turned by the output shaft of the gearbox.

I would suspect the speedometer itself. They have been known to go bad intermittently on S13s. Eventually it will fail completely.

See if you can swap out with a known good speedo. If that doesn't fix it, I would suspect the VSS itself or any part of the VSS wiring that may be shorted.

[fliprayzin240sx]

Its not the cluster, Ive changed the cluster before and this one works for sure (had 3 different S14 clusters). At first I thought maybe its the wiring, but checked for continuity all the way to the ECU and its good.

In my head, its saying VSS cuz itll start working after driving for a while. Turn off the car, let it cool down, start it up, its dead again. Have to drive it for awhile again before it starts working again. Figured if its the wiring or the speedo, it would never work at all.

[projectRDM]

Pull it out, see if the gear is damaged or shredded, could be slipping against the output shaft if it's not perfectly aligned.