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Gee Officer, My Speedometer Is Broken

Q. Hello hello! I am so glad I found you. All Info About.com is really an interesting place. I didn't know what to do and so here I am writing you.

This is my problem. My boyfriend and I are driving to my relatives house on Saturday. The only problem is, well, his car. It is an '89 Geo Prism in rough shape. I know there is no way my VW will make it, so we have to take his. The only problems are that the speedometer's broken and I have too many tickets already. I also don't think he can drive the whole time in the slow lane either. Could you please assist us. What parts do we need to buy to fix it and is there a place where I can find out exactly how to. We don't have enough money to take it to a shop.

Any words of advice, except to throw the stupid car away, would be greatly welcomed. Thank you so much for your time and consideration.

Sincerely,
Natalie

A. Well Natalie, I have some good news and some bad news for you. The bad news is that chances are real good that the speedometer cable is broken. The good news is, it's not hard to replace.

The speedometer cable goes from the transmission directly to your speedometer in the dash. Look at the firewall from the engine side and you will see a black cable about a ½" thick coming out behind the instrument cluster. That's the speedometer cable housing. Trace it down to were it meets the transmission. There will be a large, screw on type connector. With either the proper size wrench or a pair of pliers, unscrew the fitting and remove it. Inside you will see a cable with a square end. That is you will if it's not broken off. If you don't see it, look into the fitting it screws into. You will see a square fitting that the cable fits into. If the piece is in there, pull it out with a pair of needle nose pliers. Chances are it won't be broken there.

Now sit in the car (I'm assuming your boyfriend has been doing the dirty work so far) and watch the needle in the speedometer. Have him turn the cable itself sharply in both directions and see if the needle moves. If it doesn't, then you have a broken cable or a bad speedometer. But I'd bet real money it's the cable. If he has a reversible drill, he can chuck the end of the cable into it and run the drill in both directions, that will tell for sure.

If it does move or show a speed, then you have a bad pinion gear inside the transmission. The only way to fix that is to open up the transmission and replace it.

Okay, to replace the cable follow it from the transmission to the fire wall noting the route and undoing any holding attachments. When you reach the firewall, it's time to move inside the car. The instrument cluster has to come out. You can go to the library and look up the procedure for that exact car. If you can, check out the book and bring it home. If not, photocopy the page(s) and use that. Removing the cluster is not that difficult to do.

Once you have it loose, push the cable through from the engine side and guide the cluster out. There are generally 2 large plugs that plug into it. Move out the cluster enough to reach the plugs and unplug them. You have to be gentle, even though they are hard to unplug. Once you have them unplugged, it's time to unhook the cable from the speedometer. Some have a plastic latch you have to press to release it, some are screw in and some are a push and twist.

Once you have it disconnected, pull the cable out from the engine side and throw it away. To install the new cable, just reverse what you just did. And that's it, you're done. Take it for a ride to make sure it works and you're in business. Make sure when you put the new cable in you do not kink it or run it near anything hot. Just route it the same way it was and you'll be okay. One more thing, I would recommend taking the old cable with you when you go get the new one, just so you can match it up and be sure you're getting the correct one.

And Natalie, if all else fails, you can throw the stupid car away. ::Running for the door::

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Additional Information provided courtesy of AllDATA and Warranty Direct
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