racer_acks

Hi I have a 1992 Lexus SC400 and I am having problems with the headlights. When I go to turn them on when it is dark, the headlights won't come on. Then when I click on the high beams, those don't come on either and the high beam indicator doesn't come on either.

When I turn the lights on, all the parking lights do go on however and the brake light works. It is just the high and low beam headlights that won't come on. When it first started happening all I had to do was drive the car for a half a mile and then the problem would be solved! It kept coming on after driving for a little while but now it is to the point where the headlights won't work at all.

I don't think it is the bulbs because how they would come on after a little bit of driving. And I checked the four fuses in the engine bay and they were all good. The only other component I could find was the relay which I don't think is the culprit because I changed it for another one out of my other car and still no lights. The relay was not the exact same but it worked again in the original car.

Can any one help me with this? It is pretty urgent because I am trying to sell it. I looked through all the headlight(s) threads (search tool is not that great) and only found one other guy with the same problem but no answer.

It's some switch that is switching on and off, I don't think it is the relay. PLEASE HELP!!! Thank you!

racer_acks

I am almost positive that it is not the relay because I used the LS relay in my other car and it worked fine.

I am trying to think what other system has to do with the headlights and shutting them down. There is something switching them on and off from another system I think. Please help!!!!

racer_acks

When I said LS relay I really meant my SC 400 stock headlight relay. There are no fuses related to headlights in the drivers kick right? I am pretty sure of this.

soarer13oy

iTrader: (13)

maybe the headlight switch?

racer_acks

Thanks a lot for your response! It is a 1JZ. The switch itself seems to be functioning fine. I guess there could be a short in the headlight switch somewhere. Is there any way to diagnosis this with ohm loads and such, also could it be a ground somewhere?

Some of the cartridge type big block fuses look a little iffy and old. Do you think any of these big block cartridge type fuses under the hood in the fuse panel might be the culprit?

If I can I'd like to test the headlight switch with a voltmeter and keep my mind open for other culprits. The way it acts it seems like it is not the headlight switch but I am not sure.

PLEASE any advice is really appreciated!!! I am in desperate straites.

kyoso23

Seriously, try the bulbs first. When a bulb is "burnt out", it is the fillament that is broken. After hitting a few bumps and getting the fillaments to swing around a little, the can make a connection with the other pole inside the light and will stay stuck due to electromangnetic charge from the switch being on and they will work until you shut it off again. Does the little green light turn on on your dashboard when you turn the switch to the on position?

racer_acks

THANK YOU!
No. No green light comes on when the headlights are turned on with the car off or running. Also no blue light comes on when the brights are turned on car on or off. This leads me to believe that there is some sort of electrical problem that is not the bulbs.

I understand your theory kyoso but that makes sense for one bulb and not both the headlight circuit and the bright light circuit, unless they all are connected like that. I would be driving with lights not working with brights on, not working, then all of a sudden all 4 lights would come on and the blue light bright indicator in the dash would also come on.

I checked the filaments of each 4 bulbs and all appeared fine. I jiggled them all around too, to no avail.

Thanks for the help everyone! I am still searching and really need to get this fixed. THANKS!

racer_acks

It seems like this should be a common problem. I can't believe that no one knows exactly what it is. Like I said there was one other guy with the same problem but there was no solution. If anyone could help me please.

racer_acks

Well I am trying to sell the car and I have to drop my price a grand because they don't work.

Hasn't one of you sc gurus or moderators heard of this?

I don't mean to sound desperate, BUT I AM!!!!!!!!!!!!!!!!!!!!!!!!!!

racer_acks

well, no one seems to know about this issue. I was wondering if it might have to do with the daylight sensor.

Anyway I just rewired the brights to a switch inside with a fuse and ground and the brights is what I used to use as headlights anyway because the real lights are way to clouded and dim. So I hope that this might help someone that might come into this predicament.

Thanks Anyways!!

blackmagz

Did you ever find a solution? I’m having the same exact problem with my sc400. Running lights work , turn signals , hazards work. But the headlights and hi beams won’t turn on. And I had it on auto this morning and they randomly popped on about a mile down the road . Now tonight they won’t come on again ! It’s sucks not being able to drive past 4 pm because it gets dark so early this time of year ! Lol

AyyyP

[QUOTE=blackmagz;11196315]Did you ever find a solution? I’m having the same exact problem with my sc400. Running lights work , turn signals , hazards work. But the headlights and hi beams won’t turn on. And I had it on auto this morning and they randomly popped on about a mile down the road . Now tonight they won’t come on again ! It’s sucks not being able to drive past 4 pm because it gets dark so early this time of year !

KahnBB6

iTrader: (5)

I am not sure of the ultimate culprit in this situation myself but if you have checked/tested your low and high beam fuses and the headlight relay then it may be an issue related to your lighting control stalk's internal switch or it could be related to a faulty "solar" sensor (the round thing located in your dashboard top on the very edge of the driver's side) which is there in order to detect light or darkness for the auto-on system.

You can test that solar sensor by shining a flashlight directly onto it at night in order to simulate the daylight it expects in order to turn the lights off automatically when your "auto" switch setting is engaged.

However it sounds like you are having an issue getting the lights to come on even manually in the "ON" position on your control stalk.

For reference, here is the official Lexus TSRM diagram for the headlight circuit on 1992-1994 models. It should be identical to all other model years apart from 1995-2000 models having the addition of a fog light circuit (and Canadian models which have a factory Halogen style DRL circuit that U.S. models do not have).

AyyyP

After testing everything I found a bad headlight relay. I found a new replacement at a local Autozone about $28 part number 200004