Gmach

I have engine code 41 which is the throttle position sensor, which I want to change. All the video information i can find shows a single TPS on the manifold. My car has two indentical sensors side by side on the manifold. I can't find any pictures or videos of this setup. Which one is the TPS...why are there two on this car...1991 LS400. If there are two sensors how do I know which one to change...or do I change both? Thanks.

CELSI0R

Both sensors are TPS sensors. One is used by the Traction Control system, and the other is used with the throttle cable.

Some cars have only one TPS sensor, if they come without TRAC, such as my 91' LS.

I could be wrong, because I don't have TRAC; however, on the cars with TRAC, I believe the sensor closer to the manifold is the one used with the throttle cable. The outer one, further away from the manifold, is for the TRAC system.

See this tutorial on LexLS.

Bprakash

Looking at the engine bay, the TPS on the right is for engine idle control and the one on the left is for Traction Control. I changed both 4 months ago.

dicer

A tps is not for just idle control. It is there to tell the ecu the position of the throttle either from full open to anyplace between down to idle. Thus it is called a TPS which means Throttle Position Sensor. And the one that is farthest away from the intake plenum, or the first one the incoming air see's is the one for TRAC, or the one that is closest to the passenger side or right side of the car.

Gmach

Thanks for the replies....very helpful.
Now, with a code 41....which sensor is the bad one?

dicer

Using the correct jumper terminals on data connector it is for the tps and not for anything to do with trac. So that is the one closest to the plenum or towards the driver side.

Gmach

Since this car has 2 TPS sensors (idle and trac) how do you set the Trac sensor?
I know how to adjust the idle value using the idle TPS (according to lexusls.com) but what is the procedure for the Trac sensor?