hey guys i got a 1990 240sx hatchback and my speedometer is out of wack big time. First of all i drove by a police remote radar to see ur speed, well my speedometer said that i was going 25 but the police meter said i was going 32-33. Second, as i get into about 4th or so and i hit 40, the speedometer JUMPS to 55 and just sits there constantly. So what i have to do is take my foot off the gas and in a couple seconds the speedometer goes back down to 40-45 however fast i am intending to go, but when u hit the gas again it jumps right back up. So when i am getting on the highway the speedometer kind of lags as i gain speed then SLOWLY goes up past 55. mph by mph by mph.... And then sometimes the damn speedometer will just drop and dont work at all then all of a sudden pop back up. SO, my question is to yall what might be causing this, i have looked around and heard it might be my speed sensor and if so where is this located so that i could take a look myself and find it. also i heard the connections might be back in the transmission and the back of the speedometer or the soldering is crappy and might come undone. i have looked around and this seems to be a common problem and i was just wondering what yall could do to help me out. THANK YOU VERY MUCH.
Quinn:ylsuper
Speed Sensor 1990 240sx hatchback
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float_6969
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I assume this is for an analouge speedo? (has needles) If so, the problem is either in the speed sensor (doesn't sound like it) or in the actual cluster itself. The way to test it would be to pull the speed sensor out of the back of the transmission. If you are underneath there car there is a cylndrical device with 2 wires going to it at the back of the transmission. That is the speed sensor. The connection for it is up farther in the wiring loom somewhere, Unplug it and then remove it from the transmission. If you can jack the rear of the car up, it will help otherwise you will loose a bunch of transmission fluid. When you have it removed, attach a voltmeter to the plug, set it to VAC and then use a drill on high speed to turn it somehow. If you are getting stable voltage out of it at a stable speed, then it is fine. (Once again, I seriously doubt this is the problem) If it does check out alright, then it's probabally the gauge cluster and I have no idea how to check it other than replacing it with a known functional one and see if the problem goes away.
