Gs300 brake line schematic

SOURCE: Replacement brake pads for 06 Lexus GS 300?

go with standard pads.they wear a little faster than ceramics.but they dont wear down brake rotors.ceramics pads are hard and they cause brakes to squeak.also your car is under warranty with lexus dealership.i would use what they said. because you have future brake problem. they will void out warranty for not using their brakes.

SOURCE: 98 lexus gs300 codes p1120 p1121

I wanted to start a thread specifically about failures within the throttle body concerning the GS300 (1998 in my case)

My symptons were:
VSC, VSC OFF, and ENGINE Lights would come on, followed by my car going into Limp Mode, where only that last 25% (if that) of the throttle would respond (basically have to floor the pedal to even move at all).

During the mornings, or when the engine was COLD, the throttle operated normal...then once the car warmed up, usually at about 10 mins, the problem would start...it happened intermitantly at first...1 or 2 days over the course of a week, then it became more consitent, until last week it became a daily problem.

The first part I tried was the Throttle Position sensor, which is on the front side of the throttle body, and the easiest thing to replace...this didnt help at all. $300 part from Lexus, $80 part from RockAuto.com (exacly same part toyota OEM)

THE PART THAT FIXED THE PROBLEM:
===========================================
"Idle Valve Motor", which is the larger electrical object next to the TPS on my 98 GS300. Problem is solved.

The Codes I got were P1120 and P1121 - Accelerator Sensor problem. However it wasnt really the Accelerator Sensor, it was indeed to actual electrical Motor that controls the opening of the Butterfly valve inside the Throttle body.

I found the problem by good old trouble shooting, and using an ohm meter to see if the throttle electric motor was getting elev, I found that the elec motor just to the left of the TPS was basically freaking out and shutting down. The Accelerator Pedal Sensor is on the Back-side of the throttle body where the throttle cable connects to, and has a spring on it. It was fine.

GS300's are indeed "drive by wire" concerning the throttle...the cable triggers the Accel Pedal Sensor, which sends a signal to the ECU, the ECU then sends power to the Idel Valve Elec Motor (next to the TPS), which opens and closes the mechanical butterfly valve, then the TPS sensor detects how far the elec motor is actually opening the butterfly valve...its a closed-loop feed-back system, meaning any failure in any sensor will cause the entire systm to fail.

The throttle cable apparently is ONLY there to allow the fail-safe of having that last 10-25% throttle when the electronic system fails...there is a gearbox inside the throtle body which allows the tail end of the throttle to manually engage the butterfly valve...the rest of the time, the butterfly valve is 100% opened and closed via the idle control motor.

SOURCE: lexus gs300 dash lights ,sunroof,gear lever,windows, not working

hello freddy - the good news is that your lexus has a self diagnosis system built into it. this is what you need to do.

drive to an auto zone or similar autoparts store and have them put your lexus on their computer to scan for trouble codes. they offer this as a free service. with a little luck this scan will isolate the problem and the fix will be quick and easy.

if this doesnt fix it for you get back and let me know what codes popped up.

here is a link to the lexus trouble codes so you will have added insight. good luck.

http://www.troublecodes.net/Lexus/

SOURCE: TRYING TO CHANGE MY FRONT BRAKE PADS ON MY GS300

Frank, you are correct, as long as you don't disconnect a brake line at the caliper, or somewhere else, you shouldn't have to bleed the brakes. HOWEVER, you seem to have other issues with the brakes, besides just replacing the pads. Is the master cylinder filled to the correct level? Do you have to add fluid at all, and if so how much and how often? If you are adding brake fluid, you have a leak, which would explain the brake pedal 'like it has air in it' you describe. If you add fluid, check the back of all 4 wheels for any evidence of leakage. It could also be the master cylinder is shot. They can leak where it mounts to the firewall, resulting in fluid inside the car, above the pedal, which goes unnoticed. If you don't add fluid, and there are no leaks, it's either a master cylinder problem, or air is somehow in the lines, which will require bleeding. If you replace the master cylinder, 1st fill it with fluid and bench bleed it, which will save time in bleeding all the wheels. I also recommend bleeding the system to flush out the old fluid whenever you replace the pads/shoes. Fluid absorbs moisture, and contaminated fluid can ruin calipers and brake cylinders. A tip for removing brake pads, open the bleeder valve a bit will help to free them. You will need a large clamp to re-seat the caliper pistons, as the new pads will be much thicker than the old, and need the piston to be pushed in all the way. Make sure you siphon off some brake fluid at the master cyl. before you do this, as compressing the calipers results in fluid being pushed back into the system, and there has to be room for it in the master cyl. I would also recommend having the rotors turned (cut to eliminate any high/low points for smooth operation). Check the pricing on new rotors, as some cars replacements are about the same cost as having the auto machine shop turn them. Good luck!

Testimonial: "THANKS, NO I DON'T HAVE A LEAKAGE MY LEVELS ARE SHOWING PERFECT. THIS JUST STARTED A WEEK AGO I WILL REMEMBER THE HELPFUL TIPS YOU HAVE GIVEN ME. "

SOURCE: WHAT IS CODE P0715 ON A 2001 LEXUS GS300

P0715 Input/Turbine Speed Sensor Circuit Malfunction

It seems that you may have a problem with your sensor on or in your transmission.