MikeDubb

Can a faulty TPS cause my '90 LS400 to keep from downshifting at full throttle? I'm getting an error code 41 which is telling me that the Throttle Positon Sensor is faulty but I'm idling just fine. The funny thing is, is that it is not a constant problem. At random times, the TRAC light comes on and when it does, the car doesn't downshift. I'm also getting poor gas mileage (15-17mpg) and I drive 25mile each way on the freeway to work each day. I've read in other posts that a dirty mass airflow sensor (MAF) will sometimes cause this problem as well. Any thoughts?

After more research, I found that one is the main throttle position sensor and the second is the sub throttle position sensor.

Thanks VBdenny, I ran a diagnostic and am receiving a 41 error code. This is for a faulty throttle position sensor. I looked on lexls.com and found how to replace this item, but on the website it shows that there is only one TP sensor. My 90 ls has what looks like two??? I researched the web for the TP sensor and it does show that this part does effect the Trac system. I'm hoping by replacing this part, it will solve my problem. At this point, I am still confused though, as my throttle body has two identical sensors that look to be TP sensors and on lexls.com the picture only shows one. The part #'s on the two sensors are different, so when I get a chance, I'll give the dealership a call to find out the difference. If anyone has any additional info on Throttle Position sensors, please respond. Thanks for everyones help. I'll post a pic of my throttle body and the one from lexls.com tomorrow.

I have a 1990 LS400 with 125,000 miles. I recently had the engine steam cleaned. Shortly after this, I notice that the Trac light would sometimes come on. Usually only on really hot days. Although the light would be on, I didn't notice any performance issues...until today I've always loved an opportunity to utilize the power of this great V8, so as I was going to pass someone on the freeway, I stomped on the gas pedal, and nothing happened . The car would not downshift. It started picking up speed, but very slowly because it would not downshift on its own. I manually downshifted, and it took off like normal. The Trac light was on. Later in the drive I noticed that the Trac light had finally turned off, so I stomped on the gas, and low and behold, it downshifted like it should and it took off. I called the dealership, who with all of their wisdom, told me that the Trac system must be malfuctioning (duh) and that I would have to pay them $95 for a diagnostic. (Does anyone know of a good Lexus mechanic in Seattle, Washington). I'm at a loss as this is an intermitten problem. I'm hoping that this is not a progressive problem. Any ideas?

I have a 90 ls400 with 125,000miles. I'm having a similar problem. When it is really hot out, my trac light comes on. Once the trac light is on, the car will not downshift when I hit the gas hard. I can manually shift to a lower gear, but it will not downshift on its own. I called the dealer who said the trac system is not working properly (duh)...$95 just for a diagnostic.

I also have a 90 ls400 but I'm looking for a double DIN kit. Does anyone know where to get one or has anyone put a double DIN in there 1st gen LS400? Looking to install a double DIN deck or possibly a TV screen with navigation CD.

what is the offset on your new rims?

Just purchased a 90 ls. I'm looking to get some new rims. How much do you want for them? What offset are they? I'm in Seattle as well.