Stranger Things - 92 LS400 alternator saga continues - I think :o)

[threepwood]

Alternator was not charging below 1000 rpm. I know this because most of the idiot lights on the dash board lite up and would go out above 1000 rpm. Checked with voltmeter and confirmed. So yesterday morning I replaced the alternator for the 3^rd or maybe 4^th time, hard to keep track. But it's a lifetime Autozone alternator so all it cost me was my time and I'm, unfortunately, getting pretty good at it. I'm so confident this fixed it I decided to give the old girl a long trip to a dinner party (30 miles 1 way). Mostly 60+ mph highway speeds but then suddenly traffic comes to a dead stop. Remains dead stop for almost 45 minutes as we move inch by inch by some road work they decided to do during rush hour! Idle at a stop in gear was 400 rpm, and I had checked before I left with voltmeter to make sure it was charging at that speed. It was. AC was on. The car never overheated. And yes, I transferred the heat shield to the new alternator. Now the strange part. Suddenly the radio died. I mean went blank and would not turn on or play a CD. Odd, but I had read they do fail. Then suddenly every time I would step on the brake the dashboard speed and rpm needles only would go black ???? JUST THE NEEDLES, NOT THE ENTIRE DISPLAY! Let up on brake and needles light up again. A few more stops and every time I step on the brake ALL the dashboard lights go out! Then traffic lets up and the car barely accelerates, feels like it is stuck in 5th gear. I had to use drive 1 and 2 to accelerate and stop the horn blasting people behind me. I get to the dinner party and park it. 1 hour later I come out and it will not start, dead battery. I get a jump and the car eventually starts. Measure voltage at battery and it's 14.5, normal for this car. (Yeah, I carry a multimeter in the trunk. Along with a jump starter, jumper cables, a spare ECU, a spare TPS, spare brake lights, 2 spare fan belts, a spare AC compressor, a spare ignition coil, the phone number for GEICO towing, and probably more I can't remember). Start driving it and it runs perfectly all the way home, EVEN THE RADIO STARTED WORKING AGAIN !!!!! This morning I get up and it starts just like normal with 14.5 volts on battery, so the 30 mile drive home fully charged the battery. I can only guess the stop and go overheated the alternator even with the heat shield in place and the low voltage to the ECU caused it to go nuts. ECU has already been replaced with a good capacitor version so it's not likely the ECU. Of course, since there isn't any real voltmeter or ammeter in this car there is no way to tell for sure. And the idiot battery light has never come on in advance for any of the other alternator failures so I'm not at all surprised it didn't come on this time. And it's not the trunk wiring as I have fixed that issue and rechecked the fix this morning.  I'm ready to stop calling her the old lady and start calling her the old witch 🐵 I'm thinking of fabricating a better heat shield if no one has any better suggestions.

[sha4000]

Just a guess but maybe it's the Autozone alternator. I would of at the very least tried  a Denso from rockauto.

[threepwood]

Well, I fell off my roof Sunday onto concrete steps.  3 broken ribs, 5 staples in scalp, and a fractured spacula.  So for the next 6 weeks it will be real pain (not just the pain of owning this car) while it just sits in the driveway.

[sha4000]

Sorry to hear that, try to take it easy and get yourself back together.

[LSPaul]

Hopefully you're healing well from your fall. Yikes! 

In the case of my LS, I had electrical issues when I bought the car--First, no start (I first ran a jumper lead under dash to the ECU main power lead).  I was able to start the car... But there was  also no power to the HVAC blower, no charging light, radio, etc.  In my case, I checked wiring all the way from the under-hood power distribution point, through the wiring and into the car, thinking I had rodent issues to deal with.  Instead, it was a bad connection inside the car, at the fuse and breaker panel--the connector that screws into the panel apparently had enough corrosion on it to cause issues.  I removed the connector, treated both ends with DeoxIt, worked it in, then re-installed the connector.  It's worked ever since, four years on.   Check it out when you can--can't hurt, might help.

Paul

[threepwood]

Thanks, at the moment the car is in pieces in the driveway as I took (1 handedly!)  the alternator out and exchanged it again for a new/rebuilt at autozone.  Just don't have the drive to rush putting the new one back in.  But when I do I will also check the connection you suggested.

[sha4000]

We'll be waiting for you when you check back.

[vissine]

I got an alternator problem before (due to engine oil leaking out from the valve cover and camshaft). I replaced with a new alternator but covered the top of the alternator to protect it from happening again, so far so good.

[Eagle84]

Hope it gets fixed soon. 

[threepwood]

Ok, I need some advice from a good electrical guy. Here's what's going on - I put the new alternator in.  Checked the idiot light  for battery before putting it in and it was good.  Put a voltmeter on the battery.  13.3 volts on battery.  Started car, 14.2 volts.  A little low I thought.  Start driving around and as long as i keep driving voltage keeps dropping slowly.  It bottoms out at about 13.5 volts, just slightly above the battery voltage I started with.  I have never seen this from an alternator. It is acting more like a battery charger. On my ranger truck it's 14.4 continuously, regardless of how long I drive the car.  Is this normal for the Lexus???? I have never put a voltmeter on before so I don't know if something else, maybe the ECU, is controlling the alternator ??????????  Any thoughts would be greatly appreciated as with only 1 good arm (still) I don't relish the thought of pulling this d*** alternator again.  Thanks.

[threepwood]

Well, guess what.  I drove the car to autozone while the voltage was down to 13.5 and they put their tester on it and confirmed, another dead Alternator/voltage regulator.  This is quickly becoming ridiculous.  I have lost count on the number of alternators I've put in/out. This time i'm going to ask them to bench test the new one before I leave the store.  This one was dead out of the box, acted like this from the moment I started the car.  And once again, never a bad battery idiot light !!!!!  Guess I need to look for a nicer looked permanent volt meter :o(

[threepwood]

Ok, here what's going on now.  Autozone felt so bad about the last alternator they ordered me their 'Premium' version of this alternator, which they say is a new alternator, at no additional charge.  It does, in fact, look like new.  I put it in and it starts out at 14.4 and then as the car heats up (or maybe the battery gets recharged?) it drops to 14.0 but never goes below 14.0.  I took it back to AZ and they tested and said they consider 14.0 to be a good voltage regulator.  So no issue.  But I really need to know if this is the way the Lexus voltage regulator is supposed to work. All my other cars run 14.4 all the time, but I have never checked this before.  So can anybody answer this question?????  Thanks.

[vissine]

With the engine running, no lights (or load), the meter should read about above 14.2V. So,yours is normal. Turn on the lights and everything, it should drop a bit to maybe between 13.8 and 13.9V.. Turn off the lights and it should go up again. Your case is not normal if you ask me. Replacing the first one is normal, second strike is weird, the third one is even impossible (at least to me).. I've never been unlucky enough to replace more than two components. If it happens to me, I would say bye bye to Autozone and look where else. 

Besides the battery voltage, what else have you checked?

[threepwood]

Sorry it took so long to reply.  I have replaced the fan belt and tensioner, no real change.  But I have found in the lexus manual that in fact, the voltage regulator changes output as it heats up.  The book says : 13.7 - 14.7 @ 77F and can drop to 13.2 !!! - 14.0 at 239F.  I added the exclamation points! So I have quit, and consider the current alternator acceptable.  And for several weeks now it has charged the battery so I think I'm good.  Many thanks for all your help.

[billydpowell]

ok, I have a 99ls, bought in early 2010, I wrapped my alternator in a clorex bottle and it has been working for 7 years now

[threepwood]

Wow, great idea, thanks!!!

[martinbrown9823]

thanks for all replies it helped me also, I am a fresh towing driver at towing service in Queens, and learning new things day by day.