1990 Ls400 Dash Light Indicator Problem

[Rob En Cognito]

The light indicating that I have a break light or other light out is always on. If I do find a bulb out and I replace it then the light will go away for a little while, only to return with in a week. I also am finding that my break lights go out very frequently. Any help?

My first thought was that the sensor was bad but now I am beginning to think that something may be making the bulbs burn out quickly. It doesn't seam to be the same bulb again and again but always a break light bulb.

Thanks for any help.

Rob

[don corleone]

the 90 doesn't have a light out switch on the dash. the light labeled (Brake) is for your brake fluid. that is probly low and need a top off. if your tail lights are burning out very fast then you probly have the trunk wire split problem. very easy to fix just search the forums.

[90LS400Lexus]

the 90 doesn't have a light out switch on the dash.

Yeah and I have always thought this was odd, because even my old 1984 Honda Accord sedan and 1987 Toyota Camry sedan had this feature (back light out warning lamp) and amazed that a later higher $ luxury import does not, especially as one as advanced as the LS400 was in 1990.

Rob - I have the same problem too, but my brake fluid is full. My "brake" warning lights intensity is different at times... sometimes it not on at all, sometimes its dim, sometimes its bright. Its been like this for months. I was told it was probably the 1st stages of the alternator failing because of a power steering leak, but I do not see that the alternator is damp with fluid, but my PS is indeed leaking.

The LS has alot of taillights and brakelights, so the occurance of potential failure is higher. I have four out of six working on my car now (brake lights), but all six taillights work.

[don corleone]

you might need to rebuild your brake master cylinder. the sensor could be bad or some other internal issue. if you power steering fluid is leaking then it is going in the alt even if you don't see it coming out. basically it coats the copper slip rings and prevents the charge from coming thru. you will need a new alt in the future. when it does go out you will have 4 lights on simultaneously. brake, coolant, battery and i forget the fourth. just this summer my alt went out but would work when the engine was above 1000 rpms. but stopping at a light or just slowing down would cause the four lights to come on. alt can be rebuilt also but you wanna search or have a shop do this. i was told that all auto parts stores just send the alts to a local shop and have them rebuilt and you can have them do this for you also if you dont mind the down time.

in the attached pdf it shows how to overhaul the master cylinder.

good luck

brake_system.pdf

[1990LS400]

The 1990 LS400 I drove from new until it was 13 1/2 years had a light out indicator in the instrument cluster. It was once on for almost a year until I found a lose connection in the trunk on the wiring harness a hitch company tapped into for a connection for trailer lights.

The cause could be as simple as a bad ground or a corroded bulb socket.

[9779]

Mine comes on all the time also. I did find a brake light out this time though.

[Rob En Cognito]

The 1990 LS400 I drove from new until it was 13 1/2 years had a light out indicator in the instrument cluster. It was once on for almost a year until I found a lose connection in the trunk on the wiring harness a hitch company tapped into for a connection for trailer lights.

The cause could be as simple as a bad ground or a corroded bulb socket.

yeah, this isn't the "Brake fluid light" this is a orange light that looks like a overhead view of a car with the brake lights "shining".

[90LS400Lexus]

The 1990 LS400 I drove from new until it was 13 1/2 years had a light out indicator in the instrument cluster. It was once on for almost a year until I found a lose connection in the trunk on the wiring harness a hitch company tapped into for a connection for trailer lights.

The cause could be as simple as a bad ground or a corroded bulb socket.

yeah, this isn't the "Brake fluid light" this is a orange light that looks like a overhead view of a car with the brake lights "shining".

Hmmmm... orange light? The one on mine is red.

[eatingupblacktop]

The 1990 LS400 I drove from new until it was 13 1/2 years had a light out indicator in the instrument cluster. It was once on for almost a year until I found a lose connection in the trunk on the wiring harness a hitch company tapped into for a connection for trailer lights.

The cause could be as simple as a bad ground or a corroded bulb socket.

yeah, this isn't the "Brake fluid light" this is a orange light that looks like a overhead view of a car with the brake lights "shining".

Hmmmm... orange light? The one on mine is red.

This warning light indicates taillights are out. If the actual bulb burns out regularly, as 1990 suggests, check the wiring to your lights and the sockets for corrosion. Make sure the connection is clean and tight. Also make sure you're installing the correct bulb and that you're not buying cheap crap from china.

[eatingupblacktop]

Forgot to mention, although you're not experiencing any other probs, check the trunk wiring harness at the drivers side hinge. There are many threads you can lookup.