tom steele

I have been reading up and this seems to be a problem with both the models thats because they use the same throttle drive motor assembly I dont think it's the motor itself I think it the electric clutch thats on it that goes out over time but there's no way to even get into that clutch system to service anything.
parts numbers for all the sensors
tps 89452-30140 price $80
throttle control motor 89672-30020 labeled for gs300 $230.31
throttle lever assembly $234
so how the hell does Lexus charge $1400 for a throttle body it's only $550 in parts? and really i think you only need to change the throttle control motor but i am throwing in a tps sensor for 80 buck it worth the insurance. not going to change the throttle lever assembly i see no need. i ordered the throttle control motor to put in mine took mine out and looks just like the 300 one so i will be the guinea pig if i am right and it the same this will save a lot of gs 400 owners a lot of money. i took the whole throttle body apart to paint while its off painted it black make the polished parts pop more. then painted all the heads of the screws silver. should look good we'll see...the pics below are the start of my painting the body and the stock gs400 throttle control motor you be the judge? just look up the part number to compare pics.

GS4_Fiend

iTrader: (22)

After changing it, the ECU might need to be reprogrammed because you are introducing a new component.

tom steele

no it will go thru a learning process but you do have to make sure your tps is set correctly and i am running a piggy back tuner as well spilt second ftc1. but none of that matters if it was a regular servo motor i would say yes it would have to be calibrated but this has like a electric clutch that locks up when needed. the motor spins freely till the clutch engages. i work on electronics for work and have been for 15 years. i think people just make things so much more difficult than they really are.

toy4life86

iTrader: (4)

I think mine is bad too what is the symptoms? i hear this noise from under the dash and today i seen the pedal moving and hear some type clattering

tom steele

mine the throttle would go in and out sometime work great then other times nothing it could move the pedal but i wouldn't say it was that it could be the cruise control computer maybe malfunctioning mine never moved on its own.

tom steele

damn i need to stop writing things when i am tired what i was trying to say was my throttle just would not respond some times. one time it left me dead in the middle of the street for like fifteen minutes then started to work again and i stumbled home. i wouldn't say your problem is the same issue though. yours might be the cruise control computer which has control over that motor and might be sending false signals to the motor.

speedaddic

iTrader: (10)

believe it or not, mine got stuck and i had to throw the car in neutral and shut down off the ramp on the freeway. My family and kids were with me...

Good info Tom. I wanna see the finished product

tom steele

the paint did not turn out the way i wanted. but i guess it will do for now. it started to wrinkle in a few areas. but the black looks good though just need to get it powder coated so its a nice smooth finish. then get some stainless hardware to replace outer screws maybe some cap head allen screws might look nice. just thinking ill try some cap heads i have from work see how that looks. just waiting on the control motor to come in the mail.

tom steele

that sucks i had it die out with me once when i had my son with me but freeway is far worse place. i got the motor i ordered today and installed it was going to take pics but both my batteries for the camera were dead but they are the same motors the only difference i could find was the rubber grommet is a little shorter than ours no big deal though nothing a little black silcone wont fix

tom steele

did have to clear out my engine codes because i started the car without the dash and didnt have the abs/vsc computer in so it thru a lot of codes

tom steele

i have been doing this because a friend has a 98 gs 400 as well and his the throttle wont respond at all it will start but no throttle control i swapped out his motor as well as a tps. still nothing so i took mine that i know is fine because i drove the car out there and swapped with his and still his car did the same thing popping codes saying the throttle control motor is bad but i know its not. could this be the ecu has anyone come across this before?

tom steele

little update on this figured out its in the ecu have sent it in to be rebuilt came back twice already with same problem just sent back for a third time :/ if they dont fix it this time will have to find one doese any one know how to program the keys to the ecu what does it take? and i know the dealer does it but was wandering if theres a diy for it.

ElitistK

iTrader: (4)

it might be the wires going from the throttle assembly to the ecu. there's only 3: pedal ps, tps, and motor power/sensor.

especially with a compressor under the hood, going through more extreme heat cycles overtime will eventually kill your electronics.

ThomasGS4

iTrader: (19)

Tom, will I have to readjust the TPS after changing the throttle controller motor out?

Also, how difficult is this to change? Does the throttle body HAVE to come off? Thanks!

ThomasGS4

iTrader: (19)

Just a quick follow-up, yes the throttle body comes off and yes the TPS needs to be adjusted. I was able to adjust mine perfectly.