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Toyota Service
Toyota Service, Lexus and Toyota expert
Category: Lexus
Satisfied Customers: 4914
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2003 LS430..problem started with a quick stop someone

Customer Question

2003 LS430..problem started with a quick stop someone hit the brake and released. this occurred several times on several days. a few weeks later I made a trip 300 miles with no problem..Car was parked 3 days..
when I came home..the same jerk stop occurred as I left the driveway.. 15-20 miles down the control stopped working,ac stopped working,ESV ?light came on ,windows wers slow..then all gauges went out...A road side mechanic said alternator test showed it was bad .Battery was dead.he replaced alternator and belt but did not fully charge battery. I made it home.Two weeks later ..same symptoms..Advance Auto said alternator bad..I had it and battery changed..drove home 15 miles all ok.. cranked it again 30 minutes later and the same jerk brake stop again!!!
what in the world is going on?
Submitted: 1 year ago.
Category: Lexus
Expert:  Toyota Service replied 1 year ago.

Hello. Welcome to Just Answer. Please allow me to assist you. Whenever the electrical system is receiving less than 10.5 volts from the charging system, all kinds of bizarre things start to happen. The first thing you would notice would be accessories cutting out (cruise/radio etc) and then teh AC, windows and finally a stall conditon. The brake jerk is most likely a loos of proper voltage to the ABS control unit. When it loses power, it will malfunction. Sadly, it sure sounds ot me like you are the victim of poor quality replacement alternators. A good alternator needs to output 14.4 volts DC and, on this car, at least a minimum of 90 amps. If a lesser output alternator is fitted (below 90 amps output), there is insufficient voltage present to power all of the necessary circuits with the proper stable voltage requirement. In short, you can have a 'good' alternator, but, if it is below the needed rating, you are actually discharging the battery, because the alternator is not producing enough output to power the electrical drain on the alternator output. This causes the battery to not charge. The recommendation I have for you on this request is to return the replacement alternator where you purchased it, and get a proper alternator. A genuine Lexus re manufactured unit is your best bet here. Not only is is going to be of the correct amperage rating, it also carries a one year/Unlimited mileage warranty. If for some reason it would fail, it would be replaced for free for an entire year. Most aftermarket alternators do not provide this kind of excellent warranty.

Expert:  Toyota Service replied 1 year ago.

If you have any questions, please feel free to reply.