Electrical Issue
Thread Starter
8th Gear
Joined: Dec 2024
Posts: 8
Likes: 3
Electrical Issue
2001 LS430 had dash cluster panel lights all go out, no power to the radio, no power to the AC and no ability to shift out of P. However, the car would remain running. My first instinct was the alternator, I removed negative battery terminal whle engine running and it immediately died. I considered that confirmation that it was in fact the alternator. Replaced alternator and it acted perfectly for 10 minutes while it ran outside. Then it cut off. Now when i charge the battery it will crank but i still experience the loss of dash lights, readio, ac and ability to shift. Only now the engine stalls after 10-20 seconds.
Any help is greatly appreciated.
Any help is greatly appreciated.
Lexus Fanatic
Joined: Sep 2010
Posts: 25,962
Likes: 4,291
From: Alberta
Is your battery good? It's normal for the engine to stall with the battery disconnected, also don't do this again it can fry the alternator. If you bought your alternator at a local auto parts store return it and put the original back in.
Racer
Joined: Jan 2004
Posts: 1,923
Likes: 464
From: North Carolina
In the old days it was common to unplug the battery to check alternator while running but that was before the days of all the electronics in our cars. Electronics does not like pulsating DC and that is what alternator puts out as there is no capacitor inside. The battery is one big capacitor and that is what filters the DC for the electronics. Hopefully none of the modules were damaged when that was done. Are you saying after replacing the alternator everything including the dash lights were working? If so and now have problem again check voltage to make sure alternator is working. Also keep meter on battery to see what voltage is when engine dies. If the battery was fully drained it could be bad now and not hold a charge.
Thread Starter
8th Gear
Joined: Dec 2024
Posts: 8
Likes: 3
Thanks for the replies. I am charging the battery now. I will report back with battery and alternator voltage when it’s done.
Last night I got underneath to check alternator connections just to be sure. Just behind the alternator is a 4 pin connector. It looks to be bracketed on what I think is the rear sump oil pan baffle (stamped Aisin 10020). The wiring is in the same plastic sheath with the alternator wiring and appears to run to either the passenger side VVT sensor, the coil packs or possibly the MAF sensor. Apologies that I cannot be more precise.
Anyway the wiring looks to be worn and I am curious if this could be the source of my problems?
Pics attached in post below (having trouble attaching in this post -pauses at 90%)
Thanks in advance for any help.
Last night I got underneath to check alternator connections just to be sure. Just behind the alternator is a 4 pin connector. It looks to be bracketed on what I think is the rear sump oil pan baffle (stamped Aisin 10020). The wiring is in the same plastic sheath with the alternator wiring and appears to run to either the passenger side VVT sensor, the coil packs or possibly the MAF sensor. Apologies that I cannot be more precise.
Anyway the wiring looks to be worn and I am curious if this could be the source of my problems?
Pics attached in post below (having trouble attaching in this post -pauses at 90%)
Thanks in advance for any help.
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Advanced
Joined: Oct 2014
Posts: 605
Likes: 110
From: New York
2001 LS430 had dash cluster panel lights all go out, no power to the radio, no power to the AC and no ability to shift out of P. However, the car would remain running. My first instinct was the alternator, I removed negative battery terminal whle engine running and it immediately died. I considered that confirmation that it was in fact the alternator. Replaced alternator and it acted perfectly for 10 minutes while it ran outside. Then it cut off. Now when i charge the battery it will crank but i still experience the loss of dash lights, readio, ac and ability to shift. Only now the engine stalls after 10-20 seconds.
Any help is greatly appreciated.
Any help is greatly appreciated.
Pit Crew
Joined: Apr 2011
Posts: 175
Likes: 19
From: Ga
Check 140A fuse , engine bay on passenger side next to battery
you should be able to visibly see if fuse is blown thru clear plastic top, or remove top cap to test with multimeter or test light
you should be able to visibly see if fuse is blown thru clear plastic top, or remove top cap to test with multimeter or test light
Last edited by xtr3me; Aug 11, 2025 at 07:49 PM.
Driver
Joined: Feb 2024
Posts: 63
Likes: 7
From: Ohio
Can you get a clamp or probe at the post coming out of the alternator and then put your ground terminal directly to battery ground? This will be the best way to tell you if your alternator has an issue or if there's an issue in the wiring itself. You could also have an issue with your wires that go to the battery terminals being loose.
Anymore parts are junk and I have gotten bad remanufactured alternators. You can have an auto parts store load test your alternator if you are able to pull it back out.
Anymore parts are junk and I have gotten bad remanufactured alternators. You can have an auto parts store load test your alternator if you are able to pull it back out.
Last edited by Duowing; Aug 12, 2025 at 05:48 AM.
Racer
Joined: Jan 2004
Posts: 1,923
Likes: 464
From: North Carolina
As said the fuse should be checked as the first alternator diode could have shorted and blown the fuse. Also wiring at plug should be checked. The voltage check verifies the alternator is not working.
Instructor
Joined: May 2007
Posts: 808
Likes: 360
From: CA
Best of luck and let us know if you have any questions!
