talltrini1

Hi all, hoping someone can point me in the right direction here.
I was driving my SC yesterday when all of a sudden I noticed it wouldn't accelerate. Idle was fine, but I did get a check engine light. I pulled over, popped the hood, all looked fine, no obvious leaks or anything. Pulled the throttle cable, no response. I shut the car off, then started it again, and I was able to drive a little ways normally, but then it happened again. The only way I was able to get the car moving again was to completely floor the pedal - like past the kickdown point - and even then, I wasn't getting full power.
I got it towed to a shop near my house, and what they're telling me is that I need a whole new throttle body assembly because of failed sensors - which would cost me $1900!!! If that's the case, I'll be buying a new car asap, lol. I asked him if the sensors couldn't be replaced, but he seems to think they don't sell them separately.
I'm going to get a second opinion, but does this sound legit to anyone?

t2d2

iTrader: (8)

Isn't the only sensor on the throttle body the TPS? You can buy used ones for under $50. I don't know about the '99 setup specifically, but it can't be that different.

gerrb

iTrader: (34)

Tell them to stop guessing, lmaol. You have an odb2 car so reading the error codes should be easy. If it was a sensor it will throw an error code. What error code did they get that tells them a sensor is bad ?

Depending on whether you have traction control , there are three or four components on your throttle body has electrical connections .. TPS , Sub-TPS, IACV and Traction control Motor.

You should have a CEL light with an error code.

Check your cat converters that the honey combs haven't collapsed inside which restricts exhaust flow that can cause you not revving higher and have power.

t2d2

iTrader: (8)

I forgot the SC300 places the IACV on the throttle body, but that isn't considered a sensor, is it?

I don't know what the Sub-TPS is; woulda thought that's just another name for TRAC, which I was thinking had gone away by '99 but wasn't sure.

olmytsi

iTrader: (2)

Even if you need a tb, just get one from a junkyard...$50 max.

talltrini1

I took it out from that shop and took it to a dedicated Lexus guy (he's factory trained). Cant remember the exact details, but he said this is not an uncommon issue, and he thinks cleaning out the throttle body and potentially replacing the sensors should take care of it. He did pull the codes - when I speak to him again I'll get the exact details and update the thread

talltrini1

Ok, update. Cleaning out the throttle body fixed the issue, but apparently I have a bad accelerator pedal position sensor, which is apparently $505. A lot better than the $1900 I was quoted, and they assure me that that'll fix all that ails me. Anyone know where I can potentially get one cheaper?

gerrb

iTrader: (34)

ebay but make sure it is guaranteed to be working .

talltrini1

Is this it?

gerrb

iTrader: (34)

If I were you I would ask them for the part number so you are sure of what they are referring to .

But yes it looks like it since that is the lever for the throttle cable . There is a sensor there which is the accelerator pedal sensor. It tells the engine ecu how much have you pushed the accelerator which determines how much the throttle body plate is opened.

zneubauer

iTrader: (2)

That's not right at all. I'd get it towed home and do the troubleshooting myself if I were you. Less cost and you get to learn a few things, any one of us would be happy to give you advice regarding where to start.

99scMMGT

I had the same exact issue. I have a sensor that works if you need it. The accelerator pedal position sensor, the $500. Message me if you still need it. We can work out a fair price, I just want what I paid for it. I also have a complete throttle body if you need it.

talltrini1

Already got it fixed, it was the APPS. Thanks for the follow up though guys - the car drives better overall now, and in hindsight, it had been on the way out for a while, because I'd always noticed a dead spot in my pedal travel previously

Scott79

My '99 SC 300 throwing the P1120 code in limp mode. This thread helps. Will save me a bundle if I can change the part myself.

Yamae

This video may help you in case the problem is caused by the cracked soldering joints. Mine was so and without replacing the APPS, I succeeded to fix.