here is a question my car has been in storage for a year. before i put it away i was driving on the freeway battery light kicked on and car died. tested the alternator and it tested good but i already wanted a higher amp alternator so i used that time to install an optima red top and a beefed up reman alternator. car still wasnt charging then i put the car in storage for a year now battery light still on, alternator still not charging the battery. alternator fuse also tested good but i replaced it anyway just for the hell of it. checked my ground straps made sure they were making good contact and they are. i also have a 98 gs300 and i took the alternator off of that car put it on mine and same thing not charging the battery. so im thinking there is maybe an issue with the 3 leads on the actual alternator plug i was wondering if anyone knows what to test each lead for? voltage off, voltage with key on? i can test my other car later tonight and get the reading when im home from work but im curious has anyone had this problem and tested those plug wires before. any other possible ideas? i heard i maybe should check the starter that seems to be functioning fine but i do know that if you have high circuit resistance or ground circuit resistance that can cause low charging output. anyone please

thanks

havent been on the forums in a year or so but im looking forwad to posting my build thats about to continue widebody, air, custom retro fit bumpers, gte , etc

 

Been down that long road. I have replaced my alternator 3 times, alternator plug,alternator wires ect ect i have replaced litteraly everything that has to do with the alternator/battery.

Okay so this is where i would start. I dont believe the alternator plug would cause that big of an issue besides MAYBE the dash light indicator. I have done in shop testing with a guy who has a bench machine and if the plug is not hooked up you might get a dash light but it will still be charging. There indeed was a problem with my plug from where it actually plugged into the back of the alternator but up to today i still didnt fix it and i am not having problems. Things to look at if the car is dying would be the alternator wires, bad alternator, bad battery or bad battery terminals those are the 4 main eletrical compents that keep the car running. i would start with the big 3 since it seems like you upgraded your alternator for running a heavy sound system, the alternator positive might be corroded especially if u have a minor PS leak. Then i would check the battery terminals and possibly change them out if they look old(cheap fix 15$). in my case, it was a bad battery even if in shops it tested good. If all else fails i would say to look for a used oem alternator (got mine for 80$ on here) the most expensive thing to replace would be the battery. Change it out and return it if does not solve the problem.CHECK your battery and terminals to start, your getting a battery light so it probably has something to do with the battery either your terminals or battery itself. In my experience when my alternator went out on me i got VSC ABS light and thats when things started to shut down until i revved it up. Hope this helps

 

hey man you know what im having the same issue pretty much but my car isnt throwing a code, but it wont hold a charge, and it idles all crazy like it is about to shut off, yet to light. I got my alternator checked and it was fine but the kid at autozone told me his computer rather said that my starter was bad.... so why would my battery keep dying right? I got a starter for free actually and im going to slap that on today, ill report back with my findings, keep me updated as well would ya! then again my bearings on my alternator are shot to hell so i prob need one anyhow.

 

I bought a new starter slapped it on. Still having the problem but I've pin pointed it to the alternator exciter wire. Just need to find out which of the 3 it is gonna get a wiring schematic. How I found out was I put a battery tester on the alternator and it tested 11.8v when the car was off the. I turned the car on and then it was get 7.6 volts and I was starring at it pissed of and I like the sound of my car so I revved it up and bam alternator started charging. What the exciter wire does is sends 12v to the alternator to fire it up to start charging and mine is not tripping it automatically so looking in wiring tomorrow

 

wow, I just started having similar issues on my 98 300. My battery light indicator came on, followed by the VSC/Trac lights. No the car is starting to do weird things, stereo turns on and off, car not shifting normal. Starts up fine though.

I wanna say its the alternator but not sure where to start?

 

Do you have a part number for the Alternator Exciter Wire ? I'm having similar issues w/ my 430. Big 3 done, new alt, new serpentine belt = charging is still wonky and never over 13.5V

 

Way back I had an issue with my Optima Shorting out internally. Replaced my battery and all was good.