Check gauge

**SandmanWs7** · 12-24-2009, 12:50 PM

Car has been running fine. Today as I was warming up the car everything was fine too. On the way to visit my mom the check gauge light came on. All I saw was the battery gauge.

is the battery going dead? Alternator?

**SandmanWs7** · 12-24-2009, 02:56 PM

As I was driving around I noticed that the needle tends to drop to the first yellow warning then back to 13. Also when I turn on the rear defrost the needle drops to where the pic above shows.

With that happening I am ASSuming it may be the alternator. Any input is appreciated.

**joejenkinsglass** · 12-24-2009, 03:20 PM

Probably the alt. You can have it checked at any part store free.

**sunsetorangess** · 12-24-2009, 04:01 PM

First check your battery connections, ensure they are clean and tight. Then i would check the alt..
J

**Hi-Po** · 12-24-2009, 07:14 PM

Originally Posted by sunsetorangess

First check your battery connections, ensure they are clean and tight. Then i would check the alt..
J

**MonteLS1** · 12-26-2009, 10:44 PM

Take it to a garage and get it properly diagnosed. Not at a parts store. Their equipment won't pick up all the problems that a professional mechanics equipment will. As a mechanic myself, I can almost guarantee that you need to replace your alternator. But you need to get a proper test to be sure, and also to make sure your battery is okay. Bad batteries and alternators commonly ruin each other. Even a good battery that very low on charge can burn out a brand new alternator. GMs also seem to be more prone to that problem. Also your service engine soon light is on. You need to get that addressed also. That means the computer has detected a problem, and you are very likely getting worse fuel mileage than you should be.

**DaddySS** · 12-27-2009, 02:41 AM

As stated above, remove and clean the connections as step one. How old is the battery? If it's 5 or more years old it's time to replace it. With all lights and accessories off does it climb back up to 13?

And yes - get the ses light addressed - there is no good reason to be driving with a warning light on.

**Too Fast** · 12-27-2009, 04:17 AM

As stated above a few times, 98% chance it's your alternator. Sounds like you have at least one open diode, causing it to barely keep up with normal electrical demands, then when you add a high current draw like your rear defroster, it can't keep up. Have you confirmed it yet? It is possible you have a shorted cell in you battery, but usually that also shows up as a slow/no crank.

**SandmanWs7** · 12-27-2009, 10:28 AM

Originally Posted by MonteLS1

Take it to a garage and get it properly diagnosed. Not at a parts store. Their equipment won't pick up all the problems that a professional mechanics equipment will. As a mechanic myself, I can almost guarantee that you need to replace your alternator. But you need to get a proper test to be sure, and also to make sure your battery is okay. Bad batteries and alternators commonly ruin each other. Even a good battery that very low on charge can burn out a brand new alternator. GMs also seem to be more prone to that problem. Also your service engine soon light is on. You need to get that addressed also. That means the computer has detected a problem, and you are very likely getting worse fuel mileage than you should be.

Engine light is on because I have removed rear O2s, cats, EGR, and AIR system.

Originally Posted by DaddySS

As stated above, remove and clean the connections as step one. How old is the battery? If it's 5 or more years old it's time to replace it. With all lights and accessories off does it climb back up to 13?

And yes - get the ses light addressed - there is no good reason to be driving with a warning light on.

Connections on battery are clean, no mold or corrosion. Battery is about 3 1/2 years old. Cheap autozone battery.

Originally Posted by Too Fast

As stated above a few times, 98% chance it's your alternator. Sounds like you have at least one open diode, causing it to barely keep up with normal electrical demands, then when you add a high current draw like your rear defroster, it can't keep up. Have you confirmed it yet? It is possible you have a shorted cell in you battery, but usually that also shows up as a slow/no crank.

Have not confirmed it yet. Will be taking care of that tomorrow. Car does not show any kind of problem starting up. Cranks on at the first turn like normal.

**Smittro** · 12-27-2009, 11:37 AM

Originally Posted by Too Fast

As stated above a few times, 98% chance it's your alternator. Sounds like you have at least one open diode, causing it to barely keep up with normal electrical demands, then when you add a high current draw like your rear defroster, it can't keep up. Have you confirmed it yet? It is possible you have a shorted cell in you battery, but usually that also shows up as a slow/no crank.

This.....

**SOMbitch** · 12-28-2009, 12:56 PM

I just put an alternator last month and that is exactly where mine read on the gage. it would just randomly go down and I would rev it up and it would start working.

Just a tip....I took mine to a local rewinding shop and had it rebuilt for half ($75) of what AZ, AA (the chains) wanted for a reman one....