Rokas

Let me start from the beginning so you know what killed the alt and I'll get to what the car is doing now. I don't understand it.

I had a bad oil leak that killed an alternator in 6 months. I had changed it out in January. Not long ago, I suppose the oil killed it.

Because it was only 5-6 months, I thought it might be a loose belt or something else so I checked some things first. The belt actually was loose and coupled with the fact that that bad alternator was also harder to turn, the old loose belt I had wasn't even spinning it.

So I thought that was the problem and changed out the belt. Now the belt was strong enough to spin the alternator but actually the alt was bad too, I ended up finding out.

I took it to AutoZone by itself and they tested it in their machine. It failed badly. So I got a replacement one and went home to put it in. Of course, I had cleaned off as much oil as I could before I even took the old alt out for obvious reasons. Got it in fine, jump-started the car, and boom - no battery light, nothing. Car is running fine! I am happy as hell at this point. It had been over a month...

The next day I get in and put some gas and run an errand. All good. I figured I would put the big plastic ram-air intake piece back on as I was done under the hood. Plus I think it works better for cool air... Anyway, I don't see how this could be related in any way. BUT...

I start the car up and I thought I saw an extra red light... I did a double take... Battery light is on? OK, if maybe I hit the terminals or something, I went back and not only cleaned them again but made sure they're perfectly tight and all that good stuff.

Turn the car on. Battery light. Now I'm pissed off and frustrated. I thought I would test the flow and when the car is running, the voltage is 12.06. I know that's low. I JUST got this alternator.

Oh, I replaced the alternator fuse too (the 120 volt one).

So the car runs and drives but the alternator is obviously not charging correctly. But like I said, I've cleaned up all the corrosion, any oil, terminals - all contacts are good. There are no burnt wires so I don't think there's a short? I took the battery to get it tested and that's good. It charged to 12.76. My car will leave it at 12.3v when I turn it off.

So; new alternator and battery, car turns on every time, battery light is on, alt is seemingly only putting out 12.07 volts. Car drives fine. But what is this? Could it be a parasitic drain? Could it be another fuse? This is super annoying because I can't seem to diagnose the issue. I would really appreciate some help.

I now have wires running from the battery to inside the car to a voltmeter so I can turn that on at any time while I'm driving. I hope that the voltage doesn't start going down. Wish me luck and please give me some advice if you have any.

Fit1too

I'd suspect the alternator again. Autozone starters and alternators are hit and miss. See: https://www.clublexus.com/forums/ls-...ket-parts.html

Bylan

I don't trust autozone or any of those chains with batteries, alternator, or power steering pumps. I searched high and low for a quality remanufactured Denso alternator, looked and smelled brand new. Not a scratch on it. I know that's not the answer you want to hear, but these Lexus's are very particular about their electrical systems. Often times, a cold alternator will work fine, but when it's heat soaked in the engine bay it'll start to struggle. I believe I got mine off ebay

Fit1too

Rockauto has Denso rebuilt alternators for $130. Anyone have luck with those?

Rokas

Actually I do. I should've done it this time. I had a warranty on mine. It's lifetime - does that mean I can take it back 3 days later?

So I did some testing. I hooked up two wires from the battery to the voltmeter inside the car to show me what's going on and the alt seems to only be able to put out 12.07. That's what I see while driving. I can kinda monitor it this way but... How long til it just drops a volt or two? Anyway, when I'm on the brakes, it goes down a little of course (11.95 or so) but consistently climbs back up to 12.07. I can drive like normal wherever I want to go but... Like I said... I feel like it's just gonna die. F#$#.

I can't believe AutoZone sucks that hard...

Edit: Tonight my wife gets off work at 10pm far away and has no other way home unless I have just enough money on my card to get a Lyft. If the car dies, I can't get a tow. I feel so ****ed.

peterls

I always install alternators of higher amperage than required. You can find them easily on e-bay even made by denso (like mine). Don't remember exactly any more, but I think mine is 160amps when OEM standard is 120. I figure - if things start going south, it will be a while before it starts outputting less than 120. The price difference is minimal too..

Fit1too

You'll be running your headlights tonight also, which may make the situation worse. It will work out though. Be on the lookout for something good!

Rokas

thank God somebody gave her a ride last night. Today I started the car up and before I got outside of my neighborhood it was already dying. Has anybody literally taken back an alternator a week later to claim their warranty? It failed immediately!

Also could there be a cause besides just a bad alt? That would kill a good alternator like that? I don't have any extra accessories or anything.

Fit1too

I'd say it is just a bad alternator from the beginning. I realize that it not what you want to hear, but...

aptoslexus

You need to voltage drop test the alternator. Don't just assume it's the alternator. Bad wiring or a bad connection could affect your charging. Your volt meter should be reading 14.2 or thereabouts with the car running.

bradland

This problem seems fairly obvious. You bought an alternator from the wrong place. Return it and try again but odds are you'll be plagued with issues until you buy a quality part. As far as the retail auto part chains go Autozone is definitely the worst. Especially their in house Duralast brand. I wouldn't use ANYTHING Duralast even if it were free AND Autozone paid me!

Btw your "oil" leak is most likely power steering fluid from the PS pump directly above the Alt.
Have you resolved that issue? It will continue to leak until you do destroying every alternator you install...

oldskewel

iTrader: (1)

It is amazingly simple to open up the alternator. As easy as it is to remove the alternator, it's even easier to take the back cover off and inspect the brushes, etc. The toughest part may be finding a 7mm socket.

I would do that. And if your multimeter can check diodes, check those as well. Some simple passive bench testing like this may be better than what they do at the parts store. In my experience with them, I've had them test good alternators as bad, bad alternators as good, and damaged an alternator once, even.

Also, rather than just concluding "my alternator is bad," you may be able to isolate exactly what is bad about it. This thread that I started shows how I found a possibly similar issue with a Denso rebuild where the slip rings had failed.

https://www.clublexus.com/forums/ls-...l#post10509050

YODAONE

OP: Welcome to the repair TWILIGHT (AUTO)ZONE.

Rokas

Some new things happened.

I got it to finally charge between 13.4 to 14.4 or so while driving. This lasted for about two weeks until the battery light came back on.

What did I do? There is a piece of plastic on the bottom of the negative terminal connector. I cut that off so I could slip the connector onto the terminal more. More contact... You know?

Anyway... It was sitting for 2 weeks before this. I jump-started it and lo and behold... No more battery light. Good readings from the voltmeter.

It wasn't even overheating that bad. Everything looked OK except, after two weeks like I said, the battery light came back on when I started the car. Wait...! Actually I was driving it. The only thing I did different was put my window all the way down. Coming back up, it seems to lack the energy - somehow - to go all the way up. For example, if I'm ready to get out of the car, I have to sit there and wait cause the window will slowly go up by half an inch at a time. Revving helps.

One thing - could a short in the door cause all of this?

I don't know if these are related but soon after, there's the battery light. Keeping the car charged at 12.5 or so at all times. Not cool.

To me it's like the voltage regulator isn't working propah (properly).

I've cleaned all the corrosion three times by now. The little bit there was, anyway.

The only idea I have left is that 1. The ECU is somehow messed up. But wouldn't that produce other symptoms? 2. The electrical connector to the alt might be loose inside, not allowing the voltage regulator wire to make contact. This is what I will be looking at today - probably. (Heat index 117!!)

So I thought the alternator was bad but apparently it works... Sometimes? Maybe it's depending on the cycle of the moon?

Guys and gals, Lexus lovers, hear me.

If I sell this car, I would feel like such a failure and I would regret it to the utmost degree. StereoRob knows I did all the major maintenance. NOW some weird electrical bug is killing the car!

Don't let Lexi go out like this. I need any help I can get, please! Does anyone in Central Florida feel like helping me figure this out for some money?

This has been my dream car since I saw pics of VIP LS400s around the age of 15. If I sell it now... For $500... I should just punch myself in the face.

(Hey Rob .. I might need to hide my car at your LS-barn.)

Rokas

Yes, thank you. Well I did figure out the alt is fine considering it ran fine for those two weeks. AFTER it wasn't working.

So maybe you guys can give me ideas as to what else to check.

I replaced the belt - it was loose anyway. I actually put it on backwards looking at the letters but the belt is the same either way... Right? Seems A-OK.

I replaced the 120v ALT fuse and the 7.5v ALT fuse under the hood.

I lost my manual!!! Can someone post pictures of the fuse diagrams that list what fuse does what? I can't find it online, strangely enough.

I got my battery tested. Putting out 720 amps out of 740 that it's rated for. Passed as good.

I tried to check everything else. Now, there are obviously some wires I may not be able to see but I don't see burnt wires anywhere that would indicate a short.

Also - just cause these cars are so sensitive - I should mention a good portion of my engine is covered in a pretty thick (1/3 in.) layer of dried oil. I suspect that may contribute to overheating.

I'm trying to think of ANYTHING that would help you guys help me. Don't let another LS400 be junked.

(Crybaby story; my wife just got laid off [restaurant shut down with no warning], I had just quit a job because of health issues [wasn't supposed to be working there anyway], and although we were able to pay rent and buy some essentials, money is TIGHT right now. This wouldn't be a problem if I could pay to really have it looked at or whatever. The real problem is if rent comes up and I'm short.)

Thanks people. Much love. Please - I really need help here. I've never run into such a weird problem but also electronics is my weak point.