DMPesso

Whats up CL. So to make a long story short I just want to know if these symptoms mimic a bad alternator or battery. Basically what happened was I was getting gas and by accident I left the battery on with the heat on medium without the car running, when I went to turn the car back on it started VERY sluggish and when I put the car in drive it had no power and WOULDNT even move. I almost thought it was bad gas but I always fill up there so I figured it had to be an electrical problem. Now I know my terminal on the red one is a little weak so I'm gonna get that changed but would this seem like a battery issue or the alternator? What differentiates the two to rule the other one out? Never had altenator trouble with this car so any insight would be appreciated. Thanks guys

gsean400

Hmmm all 3 of my Lexus's at some point had a bad alternator or battery. It's hard to tell. When my battery went bad it started really sluggish as yours did. When my alternator was going out my system and navi kept cutting out and i would get a battery light in the dash. Your best bet would to get your alternator and battery checked at autozone (it's free) so start from there. They will be able to tell you if your alternator is good or not. And if its your battery check the terminals befor investing in a new battery. If they check out good it might be your fuel pump. I'm not completely sure but hope this helps till someone with more knowledge chimes in

DMPesso

Thanks for the reply. That's what I was confused about because my battery light never came on and I remember when I had an acura when the alternator went out the battery light flashed and none of the electronics really worked when I was driving. This is making me lean torwards the battery as the issue since if I drive on the highway the car doesn't have problems because that charges the battery but if I do many short trips with a lot of electronic use the car starts acting sluggish. I'm GONNA have autozone check the battery I guess and start from there, hopefully they replace it for free because I only have this battery a year or two tops

yada

When my alternator went out I had abs off abs and 1 more light.

gsean400

There is a really good possibility your ps pump leaked onto your alternator and shorted it, after replacing my alternator it had the symptoms of a sluggish start and I went back to autozone and they said my alternator was reading low volts, but this time it's not low enough to set off lights. I'm actually not going to replace anything until the alternator is completely toast befor I spend $$$ on another alternator, 6 months going weak. But I still make it from a to b and just make sure I don't leave any lights on after I turn off the car.

DMPesso

thats just the BS excuse they tell you when they want to blame it on your alternator so they dont have to warranty your battery. I REMEMBER that a bad alternator will USUALLY always display your battery light or some type of light at least once when its low on power and mine NEVER did that so I figured it had to be the battery especially because there was some corrosion on the terminal and some of the terminal wore away. I went to autozone last night to check the battery and the guy said my alternator is running at 12-13 volts and it should be running between 14-15 volts so its not properly charging the battery, I said to him can you check the battery though because it has to be bad it was corroded. He checked it and he said the battery wasn't fully charging so he can replace it for me under warranty. He said your alternator might still be bad but I am thinking it isnt becasue there were no issues besides the battery and maybe that is the correct voltage for a GS? someone correct me? So when I change the battery today I will update you guys and let you know what happens.

gsean400

Well... I did check my alternator and it was covered in fluid. And at one point I had a really loud ps pump whine that was caused by low ps fluid. So that's still a possibility lol

DMPesso

Thanks for all the feedback guys! I have been driving it for a few days now and the car feels much more responsive and faster and it has been starting up much stronger. I haven't noticed any symptoms of a weak alternator like before so I am almost positive it WAS the battery thank god. I haven't went back to autozone to check yet but I will this weekend even though I am almost certain its fine.

KeyKeeper

You CANNOT check your alternator without load on it. Everything on these cars has some sort of module/relay/computer controlling it. They are normally solid state and most circuits are controlled via micro relay with very LOW signal voltage e.g. 2-6v references. The only right way to check your alternator...short of some really elaborate Lexus diagnostic gear, is to turn everything you can possibly turn on while the car is running at IDLE. high beams/ac on max/ws wipers on max/radio on....ect. Then check voltage at the battery terminals at idle. If your below 13.2v....alternator is weak. The battery is basically a giant deep cycle capacitor so lets say your cruising down the road at 70mph and the alternator is putting our 14v at 2800rpm then in theory it is charging to its capacity. Given the amp draw of whatever you have on this may be fine at cruising speed. However, at a stop with the motor at idle, the alternator is not putting out as much. Now the battery dicharges since the alternator cannot keep up. Also, the voltage has to dip into the low 9's to trip a battery light.

DMPesso

So basically the only way to tell if an altenator is going bad is keep car idling and put as much electronics on as you can all at the same time and then see if the voltage falls below 12v? That doesn't sound right to me... Whenever the mechanics check it they don't do any of that. Can someone else confirm this is correct?

DMPesso

By the way does have a remote starter/alarm cause the altenator to die out faster ? Does it put any stress on it? Or does that only affect the battery?

JLAWS

Are you guys all driving GS400? I went thru 2 alternators within 2 years when I had my Gs400. I think Powersteering fluid was dripping on it and slowly killed them. The alternator woud start whining/humming and then months later the abs vsc lights woud come on while driving.
I noticed on the GS430 which I now have that the powersteering components are moved away for the alternator. I think it's got the original Alternator. Lexus must have corrected the problem

DMPesso

Aha! Just what I wanted to hear! Finally a problem I won't be plagued with!!!

RamAirRckt

I've heard LS's have the same issues.

Mine is doing it as well. Lexus offers a PS pump reseal kit. Supposedly not hard to do. I'll do mine this spring. I want to get my alternator out and clean it good, it is pretty nasty down there. Might bring to local motor shop that rebuilds starters and alternators and have them go through it, clean it and put new brushes in it.

I am a bit disappointed our alternators are so small (80's amp). My Fleetwood had a 140...., and that was 4 years older car with less electronics on it. But not seeing issues with lack of power. Just when rear defroster and high blower and headlights on, it drags voltage down some.

Did an alternator/battery high load test this morning (10F out after a all night soak @ 7F) and it performed like a champ.

lexo98

iTrader: (2)

I bought a WIFI OBDII reader on ebay and an App on my iPhone. It gives check engine light codes and resets. It also shows alternator output and gives a voltage reading.