Alternator or wiring?

[SilverShadow87]

whenever the car is in motion... the oil gauge randomly spins, often all the way around, and when it does, the volt meter goes down. the car drained itself on friday, i thought it was due to the rain and something shorted which i still believe because it drained again today, but never when it was dry out.. so im curious to know what could be causing the draining, and the oil gauge going nuts, and if theyre related?

 

[565bbchevy]

Re: crazy oil gauge, volt meter dropping and draining batter

It could be a bad ground on your dash causing the gauges to be erratic. But I would start by verifying your battery voltage and your alternator output voltage first to eliminate them as your battery draining problem and go from there.

 

[Pontiac455]

Re: crazy oil gauge, volt meter dropping and draining batter

Check for a parasetic load on the battery. Hook the ammeter in series with the battery and read the amperage, anything more .5 of a amp is too much..

 

[SilverShadow87]

Re: crazy oil gauge, volt meter dropping and draining batter

sure enough after I took this vid and shut it off it refused to start.

 

[SilverShadow87]

Re: crazy oil gauge, volt meter dropping and draining batter

took it to oreillys Friday and they said they both were putting out just fine... another thing to add is that it only drains when running, then after a while of sitting it manages to start back up on its own... I have until Tuesday at 9:30 to figure this out..please help..

 

[SilverShadow87]

Ive come a little further in this mystery. nothing is shorting it. i took off the negative terminal of the battery, which is brand new now. its a 100a alternator also, which replaced the 94 that was in it. when i remove the negative, the RPMs go up and i guess the alternator finally kicks on? also, with it removed, the volt meter goes up to where it should be, when normally, it is at or below 8. but rev it, and it drops, kills the radio and the check engine light comes on for a split second. So which is it, the alternator or wiring of some sort?

 

[bill]

I would suspect a wiring problem. Make sure the battery is grounded to the chassis, not just the engine....and make sure the engine is grounded to the body as well. keep us posted.....

 

[SilverShadow87]

are these the only two grounding locations? they're both securely bolted.

 

[bill]

Looks good....do you have anything wired to the battery besides the main cables>? If so, remove them and see if the problem goes away. If not, I would suspect that the alternator is the issue....maybe its defective.

 

[565bbchevy]

I would still remove and clean the grounds even though they look in good shape from your pictures and if you haven't already I would probably replace both battery cables with new larger gauge wire ones, I have seen cables that appeared to be in good shape only to find that they were corroded where the wire meets the terminal end hidden by the sheathing.
Also you can add your own heavier gauge ground wires throughout instead of relying on only the factory ones.