Speedometer jumps to 20mph when I turn car on

[Avery Williams]

Ok so I turn on my 96 civic ex and my speedometer jumps to 20mph without me even putting it in gear or even moving! I have a manual and it’s annoying trying to drive and not know where my speed is actually at…if you have any suggestions I’m willing to take them n

Topic

[college man]

see if this video helps you.

[ScannerDanner]

disconnect the alternator and see if your speedo acts normal. if it does one of your diodes in the alternator is bad and is pumping ac voltage into your system

[Heidi]

I might buy a 95 Ford Taurus that has a jumping-around speedometer. I didn’t notice any shifting problems, but that could be because it doesn’t have a tachometer and it’s got a nice quiet exhaust system–unlike most of the cars I’ve driven over the last 10 years or so! I looked under the hood and I can barely understand what I’m looking at. Everything’s packed in so close, it’s nothing like my Honda. Would the speed sensor be reasonably accessible on a 95 Ford Taurus? Is it in the same place and stuff? THANK YOU!!

[EricTheCarGuy]

[quote=”Schatzie” post=99686]I might buy a 95 Ford Taurus that has a jumping-around speedometer. I didn’t notice any shifting problems, but that could be because it doesn’t have a tachometer and it’s got a nice quiet exhaust system–unlike most of the cars I’ve driven over the last 10 years or so! I looked under the hood and I can barely understand what I’m looking at. Everything’s packed in so close, it’s nothing like my Honda. Would the speed sensor be reasonably accessible on a 95 Ford Taurus? Is it in the same place and stuff? THANK YOU!![/quote]

It would be best to start a new thread for this problem since it’s not related to the vehicle in the original thread.

That said, before you go diving into the speed sensor on that vehicle you should check to see if it’s putting out a signal. I usually check it with a scan tool that reads live data. You can pull up vehicle speed. If you don’t see a reading there then you can reasonably assume the speed sensor or wiring is faulty. If you do see a reading, look elsewhere for the problem.

[Heidi]

What other components are there to a speedometer (particularly ones that might cause the needle to jump around)? I couldn’t find instrument panel stuff on the FAQ. Is that stuff best left to professionals? I do have small hands and skinny, flexible arms, and I’m starting to get a pretty respectable tool kit (for a girl, anyway,) so I might be able to get to it!

[Author]

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