Need help diagnosing source of problem

[Jerry Jarreau]

Hi everyone,

I have a 1.8L v6 MX3 GS and recently, the "charge battery" light in the console has begun to light up. At first, it only lit up when the engine was running under 1200rpm... now it lights up anywhere under 2200rpm. It seemed to get progressively worse over the course of a week. I would like to know how I can dianose the problem. What is the proceedure for isolating the bad part? I don't know if it is the battery, alternator or something else! I want to learn how to repair/maintain my own car, and am hoping to get some tips here, so please help if you can.

Thanks in advance,
-Jerry

[christexan]

Sounds like your alternator is probably dying, but it could be your battery also (or both, as strain on one can kill the other one after not too long)... other easy things to check first though...
Check battery cable connections... remove the cables, clean the clamps (and check for cracks), and the posts, and reassemble. Follow the battery wires as best you can, you can pretty easily see the ground connection to the firewall (just behind the battery) and if you peek under the intake ducts, can see another connection to the block. If those look badly corroded or any other source of problems, could be a grounding issue.
From the description though, it's probably your alternator dying, and as it gets weaker, it takes more revs to generate enough charge to maintain your electrical system (why the light is coming on higher and higher). Go to your nearest friendly autostore and have them test both the alternator and battery (larger chains usually do that for free). If those check out fine, then it gets harder, I'll leave that to others to reply.

[PATDIESEL]

The easy way to diagnose this is to take your car to AutoZone and they will test the charging system and battery for you for free.

[Jerry Jarreau]

Thanks guys. I did bring it to Car Quest, and they said it looks like the alternator. I will be changing it tomorrow. Thanks for your help.