My handbrake warning light remains on all the time even though the handbrake is fully released and the master cylinder fluid reservoir is fully topped up. I have a '98 LS400.
Any help would be appreciated, thanks.

Check your brake lights. There's an undocumented feature that you'll get a warning light when one of your brake light bulbs fail.

Wow, thanks! It did turn out to be the stop light bulb, that'll save me hours of investigating!
Thanks again!

Phew! Had this happen to me this afternoon, thank goodness for this thread.
I just wonder how many people have looked in the owners manual, checked their fluid levels, seen there was nothing wrong and taken the car off to Lexus for investigation.
I straightaway thought that it must signal a bulb is out, and you can imagine my horror when it nowhere mentioned it in the owners manual.
The owners manual says that it signals the hand brake is on, or brake fluid is low, otherwise there is a problem with the braking system and the car should be taken to a Lexus dealer immediately !
Lexus may build the best car in the World but their owners manual.....Mmmm...Thats a different story !

It this feature in just 98 models or earlier ones too?

[quote name='Seb Harvey' post='631491' date='Jan 31 2009, 05:44 PM']It this feature in just 98 models or earlier ones too?[/quote]

My '94 LS has a separate warning lamp for a problem in the brakes (red exclamation inside a circle with brake shoes) to the parking brake (P on a red background). The owners manual is similarly unhelpful, though, suggesting that if it's lit there is a "serious problem" with the brakes (i.e. a bulb is out, or fluid level is too low - one is a real problem, the other isn't...)