LScowboyLS

very shrewd advice

bass911

This is what it reads at idle


This is what it reads in the trunk while running. I turned up the music and the voltage barely dropped. I still think it should be higher?

LScowboyLS

yes, should be higher, more like 13.8V or more, try these two simple fixes first, before buying a new alternator

● a new battery (not kidding)
● this $15 part from any Toyota dealership (the factory + terminal), p/n 90982-05037 (they get hidden corrosion in the inside, robbing power)

although from looking at your pic, your positive battery terminal is a ways from stock, are you using a + battery cable of at least the factory quality and gauge?

the LS400 alternator is kind of on the edge of what is required, just for the car, if it is stock, that is just 80 amps and doesn't really have any extra current for your big mystery extra wire

also, in your pic, where are you taking the measurement? - we can't see where the test leads go!

simrx3

load sensative alt. it should be running at 14.1 volts..

is your alternator charge light on the dash working?

the L wire (one of the wires in the 3 pin plug, look at bottom of alt for pinout diagram) to the alternator should be reading exactly what the B+ (large wire terminal) should be. this is when ignition (reds) is on

or the alt isnt sensing any voltage so then it doesnt know what output to put out..

if the globe is blown on the dash this will cause this too..


plus bench test ya alt at ya local auto elec to be certain the alt is ok too



ps just thought too.. on the factory system i think the alt gets an input from the ecu.. so the capacitor issue might be the prob too..

bass911

The battery is new and I don't see any corrosion. I stuck the lead in the positive wire coming from the alt and stuck the negative lead through the wire insulation. The factory wire looks like it is 4 gauge. I'm going to Autozone in a few minutes and I'll get back with you.

This is the trunk but I did the front the same way as far as the leads.

bass911

Where is the charge light located? I don't see any dash lights on. Maybe I'm overlooking it.

nthach

Aftermarket remans aren't known for quality or consistency - AutoZone uses Delco-Remy as their remanufacturer and their non-GM/non-AC Delco remans use cheap parts. I'd get a Denso instead.

Get the battery checked too - bad batteries cause alternators to work harder and die quicker.

nthach

And if you're running two batteries wired in parallel, I'd run an isolator to keep things charged properly.

http://www.oreillyauto.com/site/c/de...0356&ppt=C0061

LScowboyLS

I second this advice!

bass911

Back from Autozone. They said the alt is charging but not at what it should be and also said the regulator was bad. Are Duralast alternators junk for our cars or could it be the ecu making the alt appear bad? I don't see any point in replacing a new alternator with the same one just to have the same problems happen again. They also said the battery is only at 75%, but that is the alternator causing that.

Any of these any good?
http://www.ebay.com/itm/Lexus-LS400-...0f0911&vxp=mtr

http://www.ebay.com/itm/LEXUS-ALTERN...612299&vxp=mtr

LScowboyLS

If it were me, I would get the first one you listed on those ebay links (the 200 amp) and I would get two NEW high quality batteries, Wal-Mart's best battery is made by Johnson Controls and they are pretty good. - I think they are about $80 - if one of your batteries is truly new (purchased in the last few months), go back and swap it for a new one

nthach

What you want is a Denso First Time Fit reman. Yes, stock amperage. But a lot of non-Denso remans aren't that great. You could also try swapping in alternator off an newer Land Cruiser or LX.

LScowboyLS

I am a huge fan of Denso quality, as you well know, but the stock 80 amp alternator is just barely enough for the LS400 when a lot of accessories are simultaneously in use!

with the huge cables he has for what are apparently some high current accessories, he seems like the perfect candidate for a high output alternator, especially when it is cheaper than most, these are reman Denso, and the seller seems to have exemplary feedback, and claims to have been a rebuider since 1957, so they are not likely Chinese junk.

I don't see how anyone can expect to run a big high current sound system or whatever and stay with the stock 80A alternator, this makes no sense, electrical engineering-wise!

simrx3

its the battery symbol when you turn your reds on

simrx3

totally agree