Question about Lexus Cars & Trucks
This is on my 1999 gs300 lexus
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Posted on Jan 02, 2017
go to auto zone, advanced autoparts, or a certified mechanic and ask if they can reset the codes, it should be free
Posted on Jun 17, 2009
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.
Posted on Jul 08, 2009
First check and make sure your gas cap is tight, if this does not resolve the problem read below.
A vacuum hose has become disconnected, more than likely due to having your air filter replaced. The VSC and Check engine light typically don't come on until after 150-200 miles after the vacuum hose was pulled out.
The fix: on the right-hand-side of the engine compartment behind the big plastic housing that holds the air filter you will find a black rubber hose that is not connected to anything. Squeeze the finger clamp on the hose and slide the hose back onto the half inch nipple on the back of the air filter's plastic housing.
In order for the VSC and Check engine light to be turned off, you will need to open the fuse box, right-side of the engine compartment, and pull the 20 amp EFI fuse for 10 seconds. This will reset the system. The fuse location is marked on the lid of the fuse box, also I believe the EFI fuse is the only 20 amp fuse
. This will help. Thanks, please keep updated. please do rate the solution positively .thank you for using fixya
Posted on Dec 29, 2009
Its a Oil Control Valve most likely. Get the valve. Its like 100 from Lexus. Mine did the exact same thing with that code. GS300
Posted on May 19, 2010
SOURCE: the VSC and Check engine
Toyotas and Lexus cars have some unique feaures. If your fuel cap is loose or the O2 sensors on the exhaust are faulty this results in an emission problem and the engine computer unit (ECU) engages the check engine light and disables the VSC (the VSC light comes on to warn you that it has been disabled). However you have p0500 code which says the car has no speed sensor signal. The seed sensor is located on the side of the final drive from the transmission and its job is to measure the speed of rotation of the output shaft. The ECU will compare the signals from this shaft along with the speed sensors in the wheel hubs. If there is a difference between these signals the VSC is engaged to apply braking effort to which ever wheel is slipping (running faster) than the other or that the transmission speed sensor would warrant.
So you either have an emission fault has fed back to the VSC and speed sensor missing (p0500) condition, or you have a faulty sped sensor which has tripped the VSC light and in turn the CEL.
Check your fuel filler cap is on tight, turn radio off and disconnect the negative lead to the battery for 5 minutes (this should clear the ECU memory of the code error). If p0500 error and CEL and VSC lights come back on then check the electrical connection to the speed sensor. Ensure it is clean and making a good contact, check the wiring for continuity. If everything else looks good consider changing the speed sensor.
Posted on Sep 14, 2010
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