Speedo works some, but slow catching up to actual speed

[QuinGarcia]

I have a 90 240SX. My odometer went bad at 66,000 miles, so Nissan replaced it for me. I think they only replaced the odometer for me though. The car has 90K on it now and I have just noticed that the speedometer is slow to catch up when I am accelerating or decelerating. Coming away from a stoplight it will still be reading 25mph even though I've accelerated up to 40mph. It seems to catch up eventually in most cases, whether I be decelerating or accelerating. But sometimes it just never completely catch up. I'll be on the freeway at 70mph for 20 minutes and it is still reading 65mph. Then maybe I'll decelerate to 60mph and it will still be reading 65mph. However, If I decel or accel drastically enough the speedo will soon follow. WHat's wrong?

[drjohn]

You would have to check the speed sensor at the trans first but it sounds to me like a bad speedo head or maybe they left a connection or a screw loose on the back of the instrument cluster that feeds power or supplies grounds to the cluster.

[Bay Dog]

I likewise have a speedometer issue close to this. Where is the speedo sensor? I have been unable to locate it. I have a 90 se 5-speed. The Tach also doesn't work at all, but I am more concerned with the speedo. Thanks

[QuinGarcia]

The vehicle speed sensor should be on the tailhousing of the transmission. It's a bit bigger than all the other little sensors attached to the transmission