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VSC and VSC Off Lights - Limp Mode

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Old 02-28-13, 08:30 AM   #361
rapper3314
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Went to Lexus to get my tps adjusted and they did not. they give me the car back idling at 2 rpm smh and told me I need a new tb smh lol
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Old 03-02-13, 06:14 AM   #362
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I got me a scanner with live data and set the tps. car has been running good one whole day .
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Old 03-04-13, 11:04 AM   #363
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Another example of a person being treated poorly by Lexus Customer Service.

At some stage this will catch up with Lexus in general....its sad to see this type of fraud (yes thats what it is - FRAUD) coming from dishonest dealers trying to milk people for money rather than EARN business.

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I got me a scanner with live data and set the tps. car has been running good one whole day .
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Old 04-30-13, 04:35 PM   #364
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Hey AZ-Dave. I replaced all sensors. Even got a new MAF sensor. Double checked the gears on the TB. When I start the car up it sounds like it starts fine but when it gets to idling it shuts off. Your thoughts kind sir?
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Old 04-30-13, 04:36 PM   #365
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Another thing I noticed is when I step on the gas it just completely shuts off.
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Old 05-01-13, 03:22 PM   #366
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If the engine itself is stalling and shutting off, then you could have a host of problems.

At this stage you must scan the OBDII port for codes and see what they are...

You could be having loss of fuel pressure, or the TPS is way out of adjustment. Sorry I cant help more without being there in person on this one.



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Another thing I noticed is when I step on the gas it just completely shuts off.
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Old 05-01-13, 05:30 PM   #367
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only code was p1129. But I put in a new TCM already.
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Old 05-07-13, 01:23 PM   #368
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Here is my story...

For the last several months, my car has had a rough idle while stopped an in gear. (Low idle and has even cut off before). The check engine light comes on and off every few days or so. Also I have had the car go into limp mode in which the CEL, VSC and VSC off lights came on. I had no response when pressing the gas pedal. (I have a video). The lights eventuall went off and I havent really had any problems with limp mode since. I do want to mention when it was in limp mode it was super hard to change gears....

Now the CEL comes on and off every so often on the way to work.... I had my codes pulled and there is a list... I have an exhaust leak around my passenger manifold so I know its throwing a few codes for it....
The codes are,,,P1121
P0430
c1223
c1252
c1228
c0256
c0246
c0236
c0226.

I know all of them are not related to the the throttle control, but I know I have many of the same symptoms and it seems to be getting worse as the weather gets warmer... From what I read from this thread, it seems my APS is going out... However, did anyone else get any problems with their ABS system codes as well? My ABS system works for sure as I test it out pretty often =D...

Any ideas let me know... Im about to buy the APS tonight...
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Old 05-14-13, 05:13 PM   #369
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My car went into limp mode a year ago. i posted all the info on this thread . (along time ago) I replaced the throttle control valve( at the top of the engine ) held on by 4 screws ( around $250.00) for part. and it fixed the limp mode.

about 3 months ago my cars vsc lights came on and the car stuggled to go and had a very low idle. found out that my spark plugs were loos and had oil in them.<<< weird but when i replaced all spark plug and wires , it fixed the problem. a week later, the low idle started happening again. so i just adjusted the throttle control valve to where my idle was closer to 1000 rpms. and now the car runs smooth..

to rap this up,,, i wanted to add that my lexus has seemed to go into limp mode everytime there was an engine problem... so it could be anything. but i hope my comments have helped. and look back in the thread for what happened to me in the past.
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Old 05-15-13, 11:40 AM   #370
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When the ECU detects multiple misfires (oil/fouled plugs = misfire), it goes into a slightly different limp mode in order to protect the Cat Converters and the other systems.

It can also do this when it detects severe pinging (pre-detination) to prevent burning the pistons or valves.

The Limp mode specific to the Acel Pedal Sensor is pretty specific, in that the car will run perfectly good, then the throttle will start cutting out, and suddenly go into full limp mode. Many times the limp mode will turn off upon turning engine off and re-starting.

And when in the Limp mode related to the Acell pedal sensor, the idle will be perfect, and when flooring the pedal, it will start to drive without any rough engine, just slow to go.

The bottom line: If engine is running rough, pinging, bad idle, adn it goes into limp mode, there is a good chance is more related to ignition or Air/Fuel than the throttle body.

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My car went into limp mode a year ago. i posted all the info on this thread . (along time ago) I replaced the throttle control valve( at the top of the engine ) held on by 4 screws ( around $250.00) for part. and it fixed the limp mode.

about 3 months ago my cars vsc lights came on and the car stuggled to go and had a very low idle. found out that my spark plugs were loos and had oil in them.<<< weird but when i replaced all spark plug and wires , it fixed the problem. a week later, the low idle started happening again. so i just adjusted the throttle control valve to where my idle was closer to 1000 rpms. and now the car runs smooth..

to rap this up,,, i wanted to add that my lexus has seemed to go into limp mode everytime there was an engine problem... so it could be anything. but i hope my comments have helped. and look back in the thread for what happened to me in the past.
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Old 05-19-13, 05:59 PM   #371
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replaced APPS on Daughter's 02 GS300 today. Everything she explained said early stage limp mode. The car never threw a code so I am confused about it. She has been driving it today and no limp mode so far. Any idea why the code never displayed?
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Old 05-21-13, 11:40 AM   #372
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Different errors have different pre-requisites to throwing a code in the ECU, sometimes they can be instant if there is possibility fo damaging engine, etc...sometimes the ECU needs to see a system out of tolerance for a given period of time before throwing the code.

Keep in mind, when the Limp mode would go-away, there was no check engine light...lights would only occur when in limp mode.

Did you actually scan the ECU, or just relying on engine light?

My hunch is it simply wasnt out of tolerance for long enough period of time for the ECU to throw and store the code.

If replacing the APS worked, then I wouldnt stress about it.

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replaced APPS on Daughter's 02 GS300 today. Everything she explained said early stage limp mode. The car never threw a code so I am confused about it. She has been driving it today and no limp mode so far. Any idea why the code never displayed?
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Old 05-21-13, 04:04 PM   #373
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Except for the error code (P1121 only) I had exactly the same symptoms with my 99 GS 300 as described in the first article. My local Lexus dealer recommended a new throttle body for approximately $1,900. As the code pointed to the accelerator postion sensor, I replaced this myself at a cost of $260. After six weeks and 800 miles, so far, so good.
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Old 05-22-13, 01:02 PM   #374
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The dealers outright refuse to replace anything except the TPS concerning the entire throttle body.

Kinda Ironic....so greedy, or so wrapped with red-tape, that they forego making SOME profit by replacing the true faulty part, and will only accept the job if you agree to dump almost $2K into a car thats maybe worth 5-7K

Typical problems with business these days imho :-)

Glad to know you too have solved the problem.

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Except for the error code (P1121 only) I had exactly the same symptoms with my 99 GS 300 as described in the first article. My local Lexus dealer recommended a new throttle body for approximately $1,900. As the code pointed to the accelerator postion sensor, I replaced this myself at a cost of $260. After six weeks and 800 miles, so far, so good.
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Old 07-02-13, 12:43 AM   #375
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Quote:
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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:
===========================================
"THROTTLE CONTROL Motor", which is the long-larger electrical object next to the TPS on a 98 GS300. Problem is solved.
Lexus Part: The Lexus OEM Part NUmber:89672-30020 = $293.54 from Lexus Dealer (Confirmed Arrowhead Lexus of Arizona, Aug 28, 2009)


The Codes I got were P1120 and P1121 - Accelerator Sensor problem. However it wasnt really the Accelerator Sensor, it was the 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 voltage, 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 thru a set of internal gears, 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.
1. Would like to request a download link for the full service manual for a 1999 Lexus GS300. I know some members have access to this service manual, so please PM me if you would like to help.

2. Had the same symptoms as the OP. Problem occured after warm up (10-15 miles). Gas pedal became unresponsive. RPM bounced around then went to idle speed, and car would only run when pedal fully depressed (partially opened throttle plate via the throttle cable...limp mode).

3. Turn off the engine and wait for cool down will always restore control of the throttle plate, but problem will recur when warm. I don't have OBD II code checker so I just cleared the ECU. There is a buzzing sound from the throttle control motor when I put the key to ON without engine running. Rotating the accelator pedal position sensor by 2 to 5 degree will result in louder buzzing sound from the throttle control motor. This noise remains constant regardless of the angle of the accelerator pedal position sensor. The only way to restore the quieter buzzing sound from the throttle control motor is to put the key back to OFF.

The throttle plate moves when I rotate the accelerator pedal position sensor. I connect a volmeter to each of the two output signal wires (the two middle wires) on the throttle position sensor, and see a smooth change in output voltages (output one changes from 0.7V to 4.0V, output two changes from 2.5V to 5.0V). The other two wires are ground and +5VDC input from the ECU.

I also checked the outputs of the accelerator pedal position sensor. Again the two output signal wires put out 0.5V to 3.5V, and 2.0V to 5.0V, respectively. The other two wires are ground and +5VDC input from the ECU. The output signals smoothly follow the input from the throttle cable attached at the accelerator pedal position sensor.

I see a lot of noise in the +5VDC inputs from the ECU and outputs from the accelerator pedal position sensor, once the throttle control motor buzz loudly...yes, I use a scope to view the output waveform. If I disconnect the throttle control motor plug, then the noise goes away, but there is no more change in the outputs of the throttle position sensor because the motor is no longer moving the throttle plate. This tells me that the accelerator pedal position sensor and throttle position sensor are OK when the engine is OFF. A hot engine or one that is subjected to vibration could result in unstable output signal.

It appears that the noise seen is cause by the throttle control motor when it receives signal from the ECU.

Accelerator pedal position sensor resistance...1532 ohm
Throttle position sensor resistance...1374 ohm
Throttle control motor resistance...2.9 ohm
Throttle control motor cluch resistance...5.0 ohm

These readings are within spec for 1999 GS300.



Questions for those with a good working GS300:

Has anyone scoped the output signals of the accelerator pedal position sensor and the +5VDC input from the ECU with the throttle control motor connected and see abnormal noise? Do you hear a buzzing noise from the thottle control motor when you turn the switch to ON with engine OFF? Does this noise increase when you move the accelerator pedal position sensor by a small amount?

I think my throttle position sensor is OK.

The accelerator pedal position sensor (APPS) is probably OK at room temperature and no vibration since the output/input look good. Only unknow is the sensor resistance value of 1532 ohm. The input and outputs from this sensor look great with the throttle control motor unplugged. The fact that I see a lot of noise with the throttle control motor plugged in is a big concern. I don't think that the acceleration pedal position sensor can introduce noise into the circuit, but an out-of-range output signal from the APPS could cause the ECU to go crazy and send bad feedback to the motor.

Is the buzzing noise from the throttle control motor normal? If this unit does not buzz with a good GS300, then I would think that I have a bad throttle control motor.

I would love to know if anyone with a good working GS300 could scope the signal going into and out of the APPS with the throttle control motor plugged-in. I have access to some test equipment in S Cal.

Right now, I'm leaning toward the throttle control motor, with the APPS being next in line.

TIA,
F

Last edited by furballi; 07-02-13 at 09:28 PM.
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