ttyR2

What's the black plastic sensor for in the right dashboard defrost vent? Doesn't appear to affect headlight operation (thought it might turn them on when it's dark.)

The engine appears to like to stay at about 1300 RPMs when in gear, so driving under 30mph in town isn't really possible with your foot off the gas, and on anything other than an uphill means the car continues to slowly accelerate. In Park, the engine idles back down to 700 RPMs or so.

Does having the temp gauge flipping between normal temp and hot even with the engine not overheating fall under the "normal" instrument cluster issues the LS400 has a reputation of having?

Harky

The plastic sensor turns the lights on when it's dark. That's all.
If the ECU can't figure out how hot the engine is, it can't properly set the idle air valve. This will mess up your idle.
Check the connections at the coolant temperature sensor near the thermostat. The connection may be dirty or the sensor may be bad...

ttyR2

What position does the light control on the left steering column stalk have to be in for the automatic light control to function?

LiCelsior

iTrader: (32)

set it to "Auto"

ttyR2

Not sure what I'm missing, but I don't see an "auto" setting. There is off, parking lights, and headlights, plus the seperate collar switch for the fog lights. The only auto button I see is for the column "tilt-away" function on the side.

lexie

1990 LS has no automatic headlight. Lexus added the auto light in 1993 I believe.

ttyR2

So what's the sensor for then?

kwikrnu

I'd like to know as well. Thanks.

ttyR2

No one knows what the "sensor" to the right of the defrost vent is for on this year of LS400?

Update: Looks like it's an "A/C Solar Sensor" according to the Toyota wiring diagram. How exactly does the sensor affect the A/C system functions?

PureDrifter

iTrader: (10)

basically takes interior temp to cycle the AC on/off