Tungstn-IS

So yesterday, my charging system warning light in the gauge cluster randomly came on in my '06 IS350. I got up this morning to mess with it and naturally the light is still staying on. The battery is about 3 weeks old and tests to 12.8v, all connections have good contact, the car runs 100% fine, all electronics function properly (i.e. nothing cuts out, no dimming, etc.) and with everything turned on, the alternator tests to 14.1v .

So I'm wondering why the light is even on. The battery is brand new, the alternator is pumping the requisite amount of power and everything is functioning fine. The only thing that has been done to it lately was new tires and alignment Monday. Any input?

Gville350

iTrader: (10)

Try disconnecting the battery to reset everything; let it sit for at least 15 minutes after disconnecting. Reconnect and then do for a drive as you normally would, so the car can re-learn your driving style.

See if that helps. Any CELs?

Tungstn-IS

Well, I went out this morning to try a figure out what's going on and it went away. I'm not sure what that was all about, it never began to act up or lose charge...

Gville350

iTrader: (10)

Well, hope it was a phantom warning light.

Tungstn-IS

I do as well. I only drove it about 1/4 mile once the light came on and immediately went to testing it. Everything checked out so hopefully that is yhe case.

rayac88

iTrader: (3)

had the same issue. but my light comes on and off whenever it wants to. i drove an hour yesterday and 30 minutes into the drive the light came on and stayed on. then my amp stopped getting power and went into protection mode. it neever turned back on. i checked all the wiring on the amp and its fine. so i know its not the amp causing all the issues.
The battery was just changed two days ago. its brand new, i figured once i changed the battery the issue would stop but it is just less often. my car shut off while i was driving at 40mph three days ago i dont know what to do.

jgr7

iTrader: (1)

Check all of your ground connections.

rayac88

iTrader: (3)

all? where should i start from? thats a ton of ground connections.

jgr7

iTrader: (1)

Start at the battery,chasing down electrical is a pain thats why it cost so much at the dealer. Check the alternator connections too. Take off the neg connection at the battery and clean it good.

B16da9

iTrader: (7)

The alternator connection is great advise. I've seen them come loose causing these same type of problems(Take it this was on other cars not the IS).

rayac88

iTrader: (3)

strange in the timing of it. my alternator is less than a year old. so maybe when it was swapped they messed up. ill look around and report back in case anyone else runs into this.

Tungstn-IS

Where did you get the alternator? Some remanufactured alternators have a frequent tendency to spit the bit prematurely.

rayac88

iTrader: (3)

in the process of working on a solution. my fuse block assembly blew last week. car wouldnt start but the gauge turned on. lexus changed the main block and i changed the battery but the charge light is still coming on randomly. i bought a multimeter and when the light came on i popped the hood open and it was reading 12.8 on the battery posts then fluctuated up to 13.4 and when i went back in the car the battery light was off. it goes through random surges. i unplugged all my extra accessories in the car not to drain the battery excessively. i was told the clutch on the alternator can become loose and start spinning freely so i may have to change the alternator.

jusclark13

FWIW I have a 06 IS350 and my light came on and randomly went off for a few days. Took it to autozone while it was on and they said it had weak charge. Called local Lexus dealer and they tried to tell me the IS's alternators are some of the best and basically don't go out and he has never seen one ever fail. Well my car changed that cuz both my water pump and alternator needed replaced. Thank god for a warranty. Don't know if his helps or not but my suggestion would be the alternator is the cause, especially if u recently replaced battery.

rayac88

iTrader: (3)

It's definitely the alternator. I put a multimeter on it and dc voltage is riding 12.8 then bounces around 13.5. I think I started hearing whining today as I started the car so now I know I only have a day or two to get it replaced. Just got this alternator 1.25 years ago. Hope this isn't frequent. My car hasn't hit 100k miles yet.