Battery on my 03 430 has been dead the last two mornings. Tester at parts shop shows a good battery but bad alternator/voltage regulator. Voltage reading with when running/lights on bounced a bit between 13.3-13.7.

Planning to replace the alternator, but wondering why I'm not getting a battery warning light on the dash. Any other issues I should look out for in this situation?

 

. Not certain about your alternator. Our alternators rarely go bad but of course do eventually. My alternator for years usually puts out around 13.6 or so when warmed up. How many miles on your car? How old is your battery? A Denso alternator is the best way to go even though more expensive than most. Be certain or get a second opinion before changing. What does the alternator put out when the car is first started?

 

There was a thread on this board about changing the brushes in the alternator a while back. I would investigate that possibility before replacing the entire alternator. In many cases a "bad alternator" can be repaired for under $ 10 by simply replacing the alternator brushes. Brushes do wear out eventually. I believe there is also a YouTube video showing the procedure.

 

Your voltage is correct for these cars. A bad voltage regulator will either have very high or low volt output. Have the alternator tested for amp output as this is what actually charges the battery. If it checks out you have a bad battery even though the auto parts store says it's good. I did an alternator rebuild on this site a few months ago if you want to fix it yourself.

 

Very handy tool. May be.difficult.to isolate.the alternator. Coming directly off the alternator you are lookng for AC amperage, If the voltage regulator is external it's not hard at all. I routinely check motorcycle stators this way. Regulator is always external on bikes I have worked on.

 

Our alternators are internally regulated. You can get an amp clamp that will measure DC. Just hook it on the charge wire from the alternator for measurement.

 

My indicator light came on and immediately thought I had a bad battery....was able to get the 5 miles to home, had AAA check the battery but was told it was OK........battery died very quickly after. Had it towed to a Lexus dealership and they replaced the alternator. Very expensive repair on my year model as the alternator is very difficult to get to....5 hour job.....$1375.00!!!!!
my suggestion is don’t drive on it...get it fixed right away....me battery died within minutes of getting the indicator.

 

Alternator is an easy job with basic tools. Took an hour in the driveway to do battery and alternator for 550.00 total cost on my 2005.

 

As mentioned above, our alternators can fail, but not very often. Make sure your alternator is at fault before changing. Many owners mention their alternators putting out in the 13.4-13.8 volt range which is normal. Don't let that be the deciding factor in replacement. My alternator has always put out 13.4 volts (with lights, a/c, defroster, etc on) since I purchased it 10 years ago. I've never had a problem with my charging system or starting my car.

 

[QUOTE=dontcallme;10510721]Battery on my 03 430 has been dead the last two mornings. Tester at parts shop shows a good battery but bad alternator/voltage regulator. Voltage reading with when running/lights on bounced a bit between 13.3-13.7.

Planning to replace the alternator, but wondering why I'm not getting a battery warning light on the dash. Any other issues I should look out for in this situation?[/QUOTE}

Sorry for your trouble. Maybe these may help?

Diagnose Charging Issues

You Tube

How to identify and locate a parasitic drain

You Tube

 

[QUOTE=430SLOwner;10627991]
Sorry for your trouble. Maybe these may help?

This thread was started 5 months ago, I'd like to think he's fixed it by now...

 

Unfortunately you got ripped off. The replacement is not difficult.

 

[QUOTE=bradland;10628010]Thank you for your kind words....

 

I replaced my alternator about a month ago. I was driving on the highway and the car would intermittently shut off while doing 70. Also, the rear inner taillight would sometimes flicker or turn off completely which I thought was weird, and it had been doing that for a while but I never would have tied that to the alternator. I replaced the alternator with one from Autozone for two reasons. For one, it was on sale, and for two it has a lifetime warranty and the alternator wasn't that bad to replace at all so even if this one fails within two years its not a big deal for me to get under there and replace it again. Plus it'll give me a reason to work on the car.

Aaaand here come the comments about "You should've replaced it with OEM Denso, what are you thinking?" and "Have fun replacing that in a week". Feel free to fire away at me..... or be positive?

 

Please let us know how it works out for you. What was your alternator putting out before you had it replaced? And after? Personally I would have gone Denso but maybe you’ll have good luck. Keep us posted.