Fuel guage - What have I done?

[mechtech1]

I own a '99 Alero V6 with 95,000 miles. It has been a good one. Today I replaced the battery with a new Optima one. There was nothing wrong with the old battery, I just needed it for my truck, and thought I would treat the car to the new one. The car sat for maybe 2 full days with no battery in it. The battery change was uneventful. No shorting or sparking or anything. I did notice quite a bit of corrosion on the positive cable end, but cleaned it all up with baking soda and water.

The problem is that now my fuel guage needle is sitting on the -high- side of the full peg. Meaning it had to wrap all the way around counter clockwise. It shows no movement with the key on or off. I tried disconnecting the negative cable from the battery for several minutes in the hope that something would reset. But the guage did not budge.

All other guages and accessories seem to work fine. There is no burned smell or anything. What could I have done, and what is it going to take to correct it?

Thanks for any assistance,
Lee Richardson
Evansville, Indiana

[JTrujillo86]

First off, I don't know what exactly causes this to happen except to say when power is removed from the car (i.e. battery change) this happens. Anyway, when I had my 1997 Chevrolet Malibu, the same thing happened when I replaced the battery. On the Malibu, however, I was able to bend a paper clip and slid part of it though the little hole where the trip reset button was. Then, I used the clip to rotate the needle back to where it was supposed to be. After I did that, all was well. The tricky thing is with Alero is that no hole exists in the cluster to do something like that. The reset button is in-dash and sealed.

I did have my battery replaced under warranty by the dealer, but the gauge was normal afterwards. I would call the service dept. at a dealership and see if they have a quick fix. If it happens when power is removed, they must have an easy solution.

- Jeremy

[mechtech1]

Thanks for the information. The plot has thickened a little bit, now I see that my alternator does not appear to be charging. It was working fine before. The little battery shaped indicator light came on in the instrument cluster for about a minute with the engine running, but went out again. But the alternator is still not charging. I have a copy of the factory service manual, and the alternator terminals that should have battery voltage do have it. So I suspect the alternator itself. I will pull it off tomorrow and take it into AutoZone to see if they can check it.

Thanks,
Lee Richardson
Mech-Tech

[JTrujillo86]

Yeah, alternators are a weak point on GM N-body vehicles. It voltage regulator is usually what craps the bed, and since its enclosed in the alternator, the entire thing needs to be replaced.

Good luck!

- Jeremy

[mechtech1]

The alternator tested bad at AutoZone, so ~$175 later I have a new one installed along with a fresh drive belt. Everything is fine now except the gas guage. I will just live with it until when/if I need to take it into the dealer for anything else. I will just use the trip meter, when it gets much over 200 miles I will just keep the tank topped off.

Thanks,
Lee Richardson
Mech-Tech

[vamc]

Sounds like a sending unit has gone bad

[pjshaker]

you could try what JT did...but you would just haev to take the whole cluser apart and do it.....that would be the easy thing to try...then i would look into other remedies