I drive a 98 LS 400 with 300K miles on it. No significant repair work has been performed apart from regular routine maintenance.

I have developed a fault in the VSC system. If I drive round a freeway clover leaf ramp (tight 180 deg bend) at 30 miles per hour in the dry the VSC alarm sounds and the yellow alarm light illuminates. I am no where near the tires' adhesion limit nor anywhere near an oversteer or understeer condition. The factory "Repair Manuals" have no useful information that I can find on the subject.

This problem has developed recently. The last time the VSC alarm sounded I was on hard packed snow, summer tires and the system was detecting that I was loosing traction and needed to slow down, go home and install the snow tires that were sitting in my garage. That was last winter here in Wisconsin.

Does anyone have any ideas as to how I should correct this issue?

 

if you have just wheelspin the light will blink only and the traction control function will kick in.

if the roll sensors detect large amounts of body roll in relation to speed/steering angle, and (i think) detected slip) the light will go on AND the buzzer will sound, and the stability control and traction control will kick in.

so your 300k mile shocks are probably due for replacement and causing an undue amount of roll.

 

There was no wheel spin. It happens on dry pavement. I have the light and buzzer turn on. The shocks were replaced at 250K. I did not realize that the ride height sensors were inputs to the VSC algorithm. My car does not have air suspension and I assumed they were only used for HID alignment.

A few years ago the coupling ball joint on one of the ride height sensors seized and broke. Lexus only sell the complete sensor with the coupling attached. I fabricated a bracket to reattach the sensor arm to the suspension. I will look and see if my bracket is still intact.

 

a-as i recall the yaw control is g-sensor based, not suspension height (there are only 2 sensors and can ONLY determine front/rear height not across the axles. used for HID leveling).

no wheel spin is required to trigger the stability control, and vice versa.

 

BUT the FIRST thing to do is go have the codes checked and then we might be able to help you.....

 

I plugged in my OBD2 monitor. Zero fault codes recorded. 1998 LS 400 Elect. Diag. page 244 show deceleration V11 and yaw sensor Y1. Y1 is RHS rear and V11 appears to be below the radio forward of the ash tray.

Does anyone know the exact position of these sensors or where I might find the information?

 

maybe this will help....