Around 3 months ago, my car (2000 RX300) wouldn't start and I concluded that I had a bad battery, so I had it changed immediately. I then started having some problems where my car would shut off when approaching a stop or going very slowly (it happened twice at a red light and once when starting to reverse from a parking spot). I would turn the car off then back on and it would start up fine and run normally. My conclusion was a bad alternator and I had that switched out for a remanufactured alternator 1 month ago. Since then I haven't had any issues with the car stopping on me at stop lights but new issues have started to arise.

A little after I had the alternator changed (about a week) my battery light and ABS light will come on when I hit around 2000-3000 RPM. Usually the batterly light alone will come on at the lower end of that scale, and then the ABS light at higher RPMs and my speedometer will stop working as well when the ABS light shows. Along with these lights coming up on the dash, my headlights will get brighter at these high RPMs. I was driving around with this problem until about 3 days ago when I could tell that things weren't looking good (weird smell coming from hood of car, dark liquid splatter on the battery, radio cut out at high RPMs) until finally my car wouldn't start again. I jumped started it, took it to AutoZone to test my battery and alternator. They said I had a bad battery and replaced it for me. I left thinking the problem was fixed but when I drove off the lot I had the same lights coming on. I drove back, asked them to check the alternator and they said the battery was putting out 14+ V even after revving the engine (though the battery light did not come on when I revved it even though it normally will come on when revving the engine in park). They told me they weren't sure what the problem is, so I am here asking for any possible solutions to my problem before I bring it in to a shop and pay big bucks just for a diagnostics. Whatever the problem is, it seems to be killing my battery and I don't want to have that happen again. I'm pretty sure this problem has even cost me my brights as they no longer work after trying to put them on once only to have them fade out very quickly and not work since. Any help would be greatly appreciated.

 

Sounds like alternator/voltage regulator to me. Get it fixed quickly before the high voltage produced by a bad alternator/voltage regulator damage some of your really expensive stuff, like the engine computer, etc. Good Luck! Russ - electrical engineer

 

you might want to check the wire harness that goes into the alternator to make sure there is not a break in the wire where the plug is. i know sometimes when i go unplug one it is sometimes brittle and a wire may break causing the circuit not to be complete and overcharging may occur. other than that check all the fuses.

 

Thank you for describing your problem in detail.

Bit of education for every one:
Battery provides power for starter and then acts as a big clamp for voltage and gets recharged by the alternator. RX has alternator with built in voltage regulator which controls voltage output as the engine rpm changes.

Diagnosis:
The first bad move was to replace the alternator. Engine stalling at stop lights is very unlikely due to alternator. I have traveled for 1/2 hr just on battery power [during day time with drl on].

With good wires and connection the battery should be clamping the voltage .. unless the alternator is totally out of whack and overcharging horribly ... which seems like the problem here as the tell tale signs would be battery boiling over. Loose connections at the battery would give you starting problems [that is not the case] and bad connections at the alternator will give you spikes [that still may be the case].

I am not a fan of aftermarket alternators, and even dont trust the quality of rebuilt ones. I know it is $$$ issue, but I would throw out the alternator and get a new one. If you happen to have the old one, have it tested and put it back.

Salim

 

Thanks for all the replies.

My alternator is still under warranty so I will have it checked and replaced, I just hate how I have to pay for the labor of a faulty part given to me to the people who sold it to me, but such is life. I will post back with with my findings.

 

If the mechanic or the shop bought the alternator, then the labor to fix aught to be free (within the repair warranty period .. which can be 90days/6months/1yr). Usually they would be obstinate and keep looking for something else. Now if you bought the part and asked them to install, then they will ask for labor time again.

Salim

 

Well I just took the car back to Pep Boys where I bought the alternator and had them check it for me. They said it was overcharging my battery and I needed to replace the alternator, though they want to charge me $100+ for the labor. I guess I'll have to find someone to do it for cheaper or possibly do it myself. Are there any DIYs on alternator changes for the 2000 RX300? I remember searching before and not being able to find one but I may have somehow missed it. Anyways, thanks again for all the input.

 

Spend the $100 and be done with it . . .

 

Dont mess around with rebuilt junk! Get a new one. no more rebuilt starter`s and alt. for me. Never had any luck with so called; "rebuilt" crap. I`d be willing to bet that is your problem.

 

I beg to differ when it comes to starters. The Denso starters used in Lexus and many other Japanese brands are extremely robust and easy for the DIYer to rebuild. A $7 part and an hour of your time can save you $700 at the dealer.

 

Alternator removal and putting in a new one is pretty straight forward. The only place you can mess things up is not tensioning the belt properly. If you dont have the tension gauge, you should get the feel of the belt before you undo the alternator. You can take your RX to have the belt tensioned right to the dealer but that would be 1/2hr labor.

The question you have to deal with is what are you going to replace the current alternator with. Pep boys may prefer to exchange it. They may settle for your money back, but then did you turn in your core (old alternator)?

The brighter side of the whole thing is that you have not fried any of the electronics with over-voltage.

Salim

 

True, but the problem has to be solenoid contacts and that is not only thing that can go wrong.

Salim

 

My plan is to exchange it for another reman alternator just because it is under warranty and won't cost me anything. Do you think there is that big of a chance that I'll get another defect alternator back to back? I do not have the core as I traded that in when I got this last alt.

 

Folks who know statistics can tell you about your odds. I have already shared my opinion about reman stuff. You can ask PB to test the new out of the box, before you take it away. Take the pulley with you as the test jig may require it to be on the shaft.

One tip: Make sure your pivot bolt is loose as you lower the adjustment nut when disassembling and as you put tension on the belt.

Salim

 

I agree with Salim on this one. I have had quite a few Japanese starters apart (most of them have been Denso's) and except for the contacts (that is NORMAL for them to burn in ANY starter with enough "starts" under it's belt), they are almost "bullet proof". I have never to this day seen the brushes worn more than 25-30% in ANY of these starters, regardless of miles. I have a hard time imagining the "internals" in a Denso starter EVER going bad. I payed $5. plus shipping for the last pair of contacts I installed, and the quality was excellent. Beats a $200. rebuilt starter any day!

Addl.: Rebuilt alternators are a different story. I rebuild my own if they need it. MOST rebuilds are done by someone making minimum wage, doesn't speak or understand English and uses parts supplied from China that will be lucky to last a 90 day warranty, much less a year one. Rebuilt alternators from the well known major parts stores is asking for failure, and you probably won't be disappointed.