speedometer messed up

[thegreatestpenn 5,000+ posts]

So I put in someone's system: a pontiac grand am. He has one of those side post batteries so I had to replace the battery post with an adapter post. Well he called this morning and said the car wouldn't start last night and so he "tinkered" with the battery post and now the car works but the speedometer is screwed up. It shoots to 120 and then doesn't move or go back to normal. I told him its either a fuse, speed sensor, or speedometer motor (and really has nothing to do with the electrical system's new battery adapter). Anything I might be missing?

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[dman4486 5,000+ posts]

electronic speedometers will not operate/work properly with less than 12v.....it is something to do with the battery or it's connections if that is all you changed

 

[thegreatestpenn 5,000+ posts]

ok thanks, I'm guessing the battery is corroded around the terminal keeping voltage low

 

[dman4486 5,000+ posts]

np