IRomprey

Hello, new member here.
Hope this was the right place to post about this.

I recently bought a 93' LS off someone and the dash lights were not working. I know this is a super common problem in these models, I assure you this thread isn't entirely about that!
I've already looked into this issue and I'm buying a new dash off a trusted LS dash repairman (Jim Walker) within the next week.
I always noticed my headlights/dash lights (the ones that do work) would dim when I pressed the brake. I went to get food about a month ago and I hit the brake and the headlights went completely dark. Next time I hit the brakes the car shut off.
I took it to my mechanic and he told me I had an alternator that was overcharging my battery. My car wouldn't start and It was out of commission for about week.
Me and my dad installed an alternator and it fixed my cars problem of not starting and it's been running normal ever since.

My car headlights don't dim greatly anymore since replacing the alternator. They do quickly flash off for a second. Really fast, barely noticeable. Same with my dashboard lights, like the "P" for parking brake will dim flash very quickly, just like the headlights.
I figure I would tell the person I am buying the dash off about this issue. He told me the dash lights flashing off real quick is normal but he also said he's never heard of an LS doing the thing with the headlights flashing when the brake is pressed. Oh and the dash dims when the windows are rolled down, assuming that's normal.
So its got me a little worried that I'll get a new dash and there's something else wrong with my electrical that will cause my new dash to go out. Leaving me out like 425 dollars.

Is there anyone with 1993 Lexus that has had similar issue's to this? Mostly the headlight problems are what I'm curious about.
So far the car has run beautifully since the alternator change. I should also mention I'm no expert on cars, I know the very minimum!
Thanks for reading, appreciate it.

Moarpower

Is the battery good? These issues are not normal and are an electrical issue for sure. Im sure Yamae will know the answer. He is the electrical Guru here. He will certainly point you in the right direction if he chimes in.

Spartan536

Going out on a limb here....

This could be that trunk wiring harness issue that plagues LS400's....

IRomprey

After I changed the alternator the old battery was having a sluggish sound when I was starting my car. My dad suggested I got a new battery because the old one might be going bad after being overcharged. I got a new battery and the sluggish sound went away.
So ya, new fresh battery just installed like 2 weeks ago.

Hopefully Yamae stops by

IRomprey

Found something online on that, might be my problem.

http://www.lexls.com/tutorials/lighting/bulbout.html
This what you're talking about ? ^

Htony

Does it do it when car is stationary and you just hit the brake? IMO it is wiring harness or connector issue some where. Talking about DRL or main head lights? How about tail lights? Interior lights?

IRomprey

Yes it does it when the car is stationary.
I believe the little interior door lights dim slighty as well. Don't know about the tail lights.
Also I was unaware of DRL's in this model lexus. Are they the little yellow one's under the main headlight?

Right now I went to the store and when I had my headlights on, the AC lights were flickering, as well as the Time display next to them was black.
Then after I turned my headlights off they stopped flickering and the Time Display light came back on.

Htony

When you have alternator replaced, checked out the condition of battery? How old is it? I think charging system check over is in order if it is not done.
When car is sitting with engine off, measure the battery voltage, and start the engine and measure it again. What is the readings? Over charged batteries
often suffer internal damage such as one cell going bad.

timmy0tool

iTrader: (7)

I second this issue! check this out before doing anything else first.

Yamae

The important first step is to measure the voltage drop at each power distributing points to find out what line has the resistance applying the Ohm's law. It would be better to us an oscilloscope to do so.

The power distribution is done at the FL Box. In that box, there are two big fuses named "ALT(Alternator)" and "MAIN". Check the voltage drop between the "B" terminal of the alternator and those 2 fuses as a first step because the common power distribution points of the brake and the headlights are there. Every load is under those 2 fuses except the starter, you know.

Amskeptic

And let's double-check the grounds from the battery (-) to the engine and engine to chassis. Disassemble each one, a quick visual check won't tell you what is going on underneath.
Colin