Fatbikebum

Long time lurker, finally was able to track down a used 06 GX470 with 110,xxx miles with all service records at 5k increments, TB service @91k along with radiator, new brake pads/rotors and drive belt. Anyways yesterday while driving home from work my red battery light indicator came on. I was only 5 minutes away from home, I did turn off the nav, heat, lights as a precaution but made it without a problem. No lack of power or any flickering.

Looking over service history @the Lexus site-alternator is original and the battery was replaced in 2012@71,xxx miles. I went out this AM checked the battery with my multimeter. 12.26 with engine off, fired up car 11.60, had GF hold car pedal at 2k RPM, while adding heat, lights etc and it kept dropping til I had her cut off the engine at 11.30. Once off battery went up over 12.

I don’t have any weird noises coming from the alternator area and the belt looks brand new and properly tensioned. All connections coming from the battery look clean and feel secure.

My money is on the alternator, before I swap this out in my driveway on a 17degree day anything I could check for? I don’t have a garage so I’m dreading this one!

chiph9

With load, the voltage should be over 13.6v (as the system sees the load and starts charging) so I think your alternator diagnosis is correct.

You should think about a new battery in any case - yours is almost 6 years old.

Chip H.

Htony

Alternator is in question. Looks like it is not charging. When you started the car battery drained quite a bit, it should charge like crazy at about 14 volt.

Fatbikebum

Tdoll

tz693

You alternator is dead. The voltage should be 14V+ if the alternator is running. Your battery will drain soon if you run the car.

Fatbikebum

Just got done swapping it out. Definitely one of the harder alternators I’ve installed, took me 2.5hours. I dropped it from underneath having to drop the skid plate, rotate the sway bar down, unbolt a couple lines and remove the pulley above the alternator.

Solid 14V+ while running. Thanks for all the advice. Now back to saving for “fun” stuff

ebradford

Glad that you resolved the issue. I'm about to buy a second GX ('08 with 102k miles on it). Based on the Carfax, it had the same battery/alternator issue around 87k miles. New alternator did the trick apparently.

maxx430

care to share which alternator you purchase?

Fatbikebum

jhl247

I had the same problem but the voltage was at 14.5Volts (cigarette lighter USB charger has voltage). Ended up replacing Alternator for around $700.