Commuting home in my '99 GS300 (76K miles) my battery light comes on...not a prob...it turns off, then comes back on again in 5-10 minute intervals. No place to stop, in high-volume traffic. Light comes back on, then my climate control and radio begin to fade and flicker. In a matter of seconds, everything, including the engine, stops operating. I manage to coast to the shoulder. Did some research, sounds like a bad alternator or (hopefully) just a loose connection or need a new battery. When trying to start the car it sounds the same when you have a dead battery.

Any thoughts or anyone else have this happen? Hoping it's not a costly fix.

Thanks

SC

 

For sure sounds like a bad alternator. You can rule out the battery (at least mostly) because once the car is running the alternator can carry all the electricals. The alternator will be about $200 from RockAuto.com and is a pretty easy install. I did a write up here.

https://www.clublexus.com/forums/gs-...tensioner.html

Hope this helps you!

 

Not true. Mine did this and it was the battery. It was on a 1992 ls400 so don't rule out the battery. Do the normal checks before spending money

 

^^ There is the case outside of 'mostly'. It goes without saying, whatever you can do for free is worth trying.

 

Nice write up for the V8 guys..
OP if it's your alternator,i believe there is a DIY for the 300.....i agree it sounds like a bad alternator,but yes,check other things as well like the battery. Do a load test on it,and if possible,do the same on the alternator. Good luck!!
also try partsgeek.com for an alternator. I've bought several parts for my GS and the wife's car...great prices and fast shipping.
see link for alternators for your '99 GS300:
less than $200.00
http://www.partsgeek.com/catalog/199...lternator.html

 

Ah, dumb me, it's a 300!
Even easier though. Thanks for the partsgeek link. I can always use my own references for cheaper parts

 

Thanks kdick91, great write-up. Repair shop diagnosis said it was a bad alternator...battery moslty dead too, discharge, so not holding a charge. Getting a new battery (Interstate Mega-Tron Plus MTP-24) and alternator. Hope this is the last repair needed on my GS

 

Check the terminals and your grounding points definitely. Have you noticed the headlights being dim at night or a loss of power slow windows ect recently. It could be a combination of a bad ground motor to chassis, a loose alternator or corroded terminal on the alternator and then you throw the cold temperatures that the east coast has had over the past week or so. Or it could be the alternator. Just throwing a few ideas out. Good luck.

 

My LS is doing the same thing, as long as I dont let it idle to long it's fine. Been that way for about 2 months. Probably has a bad diode in the rectifier. No charge at idle under load but a little rev brings the voltage/amps up to normal.

 

check your battery terminals.. mine did this.. easy fix