So my 2003 Lexus Is300 died tonight while driving 50mph with my husband and 2 little girls in the car.
The trigger was the turn signal.
I went down and ran diagnostics on it, but no alternator malfunction is showing. I’ve noticed the gauge on the dash seems a bit lower than it should be... hovering above the line over 9.
I learned that the halogen lights pull a lot of power from the battery, so my assumption is that my alternator is on its way out.
Thoughts? Suggestions? Am I right on, or way off?

Thanks in advance for any input guys!
Sincerely,
Christa

 

You can use a DMM to check for voltage across the battery terminals then from the alternator to battery negative to see if you are loosing power through a corroded cable. Check your terminals. Make sure they are not corroded and tighten down all the way. The Alternator can't charge the bat through crappy connections.

So say for example you jump start it and find that while running it shows 12ish volts, but 13-14ish at the alternator. Then the alternator is good but it's not making it to the battery.

 

Thanks so much for your response! My battery is 12 volts, but did the battery alternator test thing and it lost power using various things... lights, AC.
So I had a test done in the battery and alternator and they think the alternator is bad also... the terminals are clean and good...and it’s a good battery, fully charged...

So um yeah ... damn alternator is failing me 🙁

 

It could be your crankshaft pulley. When the car is hot and idling, voltage and power steering goes down with a side of belt noise. Was about to replace the alternator but figured to test all the pulleys. My crankshaft pulley was split.

 

Sorry I missed that it tested bad. Thought it tested good so you were wondering what else could be going on. Well a bad alt is a bad alt. My suggestion: Replace it

 

Did you ever replace the alternator? Did it fix your issue?

 

We just had a hurricane and money is tight, so it will have to wait until I can afford it.
Promise to update whenever that time
comes.

 

whatever you do, don't replace it with anything other than a denso. I rebuilt mine for 75$. they just don't like to die so they show the smallest of symptoms, first time I had a low voltage I just disconnected it, cleaned and bolted it back up and ran fine for another year, then it finally **** on me. rebuilding it is so much cheaper and better than buying a **** aftermarket

 

Batteries now a days suck! They are expensive and often last for squat. Just because a battery reads 12volts means zip, its the load, and how many amps you are putting out.

 

Tomorrow “Lucy” gets a new alternator and they are going to change out the belt since they must take it off anyway... since I have no idea when the belt was changed last... figured kill two birds with one stone... and the shop isn’t charging me extra for replacing the belt, just the part cost.
I am unable to do this work myself.... not the right tools, experience and I live in a condo at the beach... so no work area is available here... and besides I think the old people would frown upon that level of car repair (other than what I have already done here)

so so wish me luck!!!