My lexus ls400 1990 keeps turning off on me - 1990 Lexus LS 400

STOPPING THE ALARM Turn the ignition key from the "LOCK" to "ACC" position. The alarm will be stopped but the starter circuit will remain disabled. Stopping the alarm in this manner will keep the alarm from being reactivated when any of the doors, trunk or hood is opened.
https://drivers.lexus.com/t3Portal/document/om/OM24405U/pdf/1-7.pdf

check belt for damage or wear ---check all pulleys a bearing maybe bad and causing a wobble or not turning --check the tension pulley if no tention belt will be to loose

It's just the annoying light because you are due for service soon. Lexus programs all of their cars to "tell you" when service is due. To turn it off, hold down the odometer reset button and press the start engine button WITHOUT your foot on the brake. Keep holding the odometer button for about 5 seconds until you see the mileage flash. Then it will go off.

push odo buttom and keep pressing ,turn ing key on w/o start engine few seconds

2002 security light keeps coming on, is there any permanent fix
besides turning key on for ten minutes

Look for a small electric motor near the accelerator cable and near the top of the valve cover.

It's call IDLE AIR CONTROL (IAC) motor.

It's job is to increase the idle when load is added.
Example: turning on headlight,turning on AC.

Testing it is simple.

Warm up you car for 10 minutes.

Locate the IAC motor

turn on loads.....AC,headlights,etc


The motor should move the idle up


If the motor does not increase the RPM then it can be stick.

Try to give it few gentle taps to free up the gears.

It can be clean if your are up to it.


This electrical motor is very expensive. Please handle it with care.

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The other trouble spot are

old accelerator cable

TPS Throttle position sensor

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I will do a simple tune up and gas treatment before starting to replace any parts.


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When a repair shop performs the maintenence, they should be able to reset it for you. usually you have to hold the trip reset in and then turn the key on, keep holding the button until it resets.

you will need to replace the unit. the only way to make it stop is to turn it off .

Yes, there are aftermarket chimes, and there is also a battery level shutoff, when voltage under 8V is sensed, it will stop the battery from working until you put a key in the ignition.
The IS 300 should have a lights on chime minimally. Is the radio a factory one?

How many miles on the GS?