treimche

I've got a 98 GS300 with 130K miles on it, and have 2 CELs that come and go at random. The CEL, VSC, and VSC OFF warning lights all come on when this happens. I know it's a common problem, but searching brings up too many questions, crap, and not enough answers. There is no Lexus dealer local to me, and even if there was I wouldn't go there because I despise dealerships and their money stealing ways. I can do the testing and work myself.

The 2 trouble codes I'm getting are:
P1120 - Accelerator Pedal Position Sensor Circuit Malfunction
P1121 - Accelerator Pedal Position Sensor Range/Performance Problem

I went off of All Data's website to see what to test, and I tested the resistance between 2 pins of the APP sensor, that checked out fine, then also tested the voltage with the throttle open, and closed, of the other 2 wires, those checked out fine. Tested resistance of each wire between the sensor and the ECU, and those were all fine. Then tested voltages at the ECU and that checked out fine. So now I'm in a pickle. Another thing I noticed while testing things, was the throttle motor was making a slight buzzing noise, which went away after I unplugged that, and plugged it back in. So I'm looking for some more things to look into here.

I don't know if it makes a difference, but the most common time when I have the warning lights come on, is when there is really wet weather, like when it first starts to rain, but it also does happen at other random times.

Thanks for any help in advance!

Carguy34

I know this is an old post, but I am having same problem. The only difference is that mine is a '99 GS400. I have also tested the same components with the same results. Mine is now bad enough that I cannot clear the code. Does anyone have any experience with this and what else should I test?

Thanks!
Brandon

treimche

I'm going to just replace the accelerator pedal position sensor on mine. I can easily tell when it's going to throw the code because the car will just start to slow down, even though I don't change the throttle position. Then I can give it more throttle, and it won't respond until I just floor it. I'm really hoping that will fix the problem.

treimche

Well I finally got around to ordering the part and replacing it, and it works perfectly now. The part I ordered was "Lever assembly, throttle" # 22060-46010. It was a little over $200, took me about 15 min to put it in, and I can't beleive I waited this long to do it. Problem solved.

sleeper408

iTrader: (6)

Treimche: I was having the same problems as well. The first time it happened a couple of months ago, the car was in "Safe" mode. It happened again today, the CEL and VSC On/Off indicators came on. I went to my girlfriend's house and turned off the car. Went back out 5 minutes later and the car did not have the indicator lights on this time and was not in "Safe" mode. I drove to Autozone to see if I could pull any codes despite everything feeling "Normal." I did in fact get codes: P1120 and P1121. Is the part you ordered-- "Lever assembly, throttle" # 22060-46010 the same as a TPS sensor? Also is that the Lexus part# and did you get it from Carson or Sewell?

treimche

No this part is not the TPS sensor. It sits on the back side of the throttle body, the TPS is on the front side. Yes that is the Lexus part number, and it came from Carson.

sleeper408

iTrader: (6)

Should I take it to the my shop (Exact) and have them check the voltage etc to see which one needs to be replaced? It shouldn't be difficult for them should it?

Still not sure whether I need to replace the TPS or APP. I've been driving around with the code for about 4 or 5 days now. Are those codes something that should be addressed immediately? I just ordered some parts before this happened and would like to push back replacing the sensor if it's not a big deal as compared to say... a snapped timing belt.

treimche

Well I don't know for sure, but I would guess that if the TPS was bad, that it woudl be throwing a TPS code. The only problem I found while driving w/ the car having the CEL on, was that most times, the tranny would shift really hard, and that didn't feel very good at all.

sleeper408

iTrader: (6)

So the codes P1120 and P1121 actually means I have a bad APP sensor and not TPS?

OBatsetswe

im having problems ordering this part, can you help out

treimche

Try calling Carson Toyota and ordering this part??

deadgirl

Hey people...

I'm having a similar issue and would like some more info on how to determine as to whether or not my problem is my throttle position sensor or the lever assembly throttle...

(2001 GS300 170K miles, all scheduled and necessary maintenance, replaced TPS already)

I'm about to go get my codes read, AGAIN (i'm going to write it down this time) but i'm fairly certain I only had one code pop up, which is the P1120... I also have the VSC light on.

Interestingly, not only are my lights on, but my car is not functioning properly either. I live in the LA area and for the past two weeks, my car has carried me around this area for 4.5 - 5 hours each day. Usually, it worked fine on the morning commute, but when I was driving around in the field in the evening, after the 60th mile and 5th hour of cumulative driving for the day, the TPS would totally crap out. Lights on, throttle body in manual overdrive, pedal to floor and hitting 50mph max. I'd let the car rest overnight and hold my breath in the morning to see if the sensor was working again. Sure enough, it was. This continued until I finally had the time to go to Kragen and get a new sensor (70.00) and installed it. (Now, I installed it myself with no prior knowledge.) I took the car out on my commute the next day and started jamming it down the freeway during my evening commute and the damn sensor went out on me again.

Is there anyway that I just didn't install or tweak this sensor properly? I'm going to try to reset the throttle body (taking the advice of a friend) by turning my key to the 1st on position and waiting 10 secs, then turning it to the 2nd position and waiting 20 secs, etc...
What's this I heard about testing to see if the circuit is open?
Could I have some other problems with my wires or throttle body itself (by the way, the throttle body is so clean it looks new, and the butterfly valve is operational)?

Your help is appreciated. You're saving a mechanic from a punch in the nose (I can't stand the way they try to rip chicks off! Grr!) and helping me with my new fave project.

deadgirl

Update --

Cleaned my air mass flow sensor which was caked with residue and got rid of the rough idle.
I bought a can of AMF cleaner... don't use anything else. I removed the sensor from the air intake hose area. The sensor is right on top staring you in the face between the air filter and the throttle body. Not a great description, but I'm new to this. I sprayed cleaner on the solenoid and the part that your plug together... (don't know the name).

On to the throttle position sensor issues
I went to a mechanic and he was nice enough to run a computer diagnostic on it. He found that my accelorator position sensor (which is on the back side of the throttle body, on top, between the throttle body itself and the butterfly valve) was grounded. He said this is because the sensor itself is wearing out. It makes sense, because the problem is worse as the day progresses, indicating the wiring inside the sensor is getting hot and brittle. Either way, I bought a can of sensor cleaner and sprayed off the area that the sensor plugs in to. I drove about 5 miles without a problem and it sure does feel better. If this doesnt fix it, I'm definitely replacing the accelerator pedal position sensor after my next pay day. I'll keep you all posted.

newgsman

iTrader: (4)

This happened to me a little over a week ago (CEL, VSC, VSC off lights), right in the middle of rush hour in the left lane. Fortunately somebody let me crawl across to the right hand shoulder. I continued of the freeway and stopped at a light. Turned the car off and back on. The lights were still there but the throttle response was basically back to normal.

On the weekend I took the throttle body off and thoroughly cleaned it using carb cleaner. I also took the pedal position sensor off but it look real clean inside. I couldn't get the screws of holding the throttle motor so I left it alone. Sprayed a fair bit of the carb cleaner around the ends rod holding the throttle plate. I also turned the throttle body on end so the cleaner would run downthe rod into the throttle motor area and the other way into the pedal position arrea. I also took the little plate of the top of the throttle body and gave the little pin holes a real good spray cleaning.

I must say after I put everything back together the throttle response seems to be noticeably better. Very smooth and much quicker response. I had reset the check codes before doing the cleaning but nothing has come since last week.

I clean my throttle body maybe once a year but always on the car. This is the first time I took it off and I got to clean the edges of the throttle plate much better. Plus I think getting cleaner into the ends of the throttle rod might have made a difference.

Going on 5 hour road trip next week. Hopefully all will be good.

BTW mine is a '98 GS400.