In case you ever wondered what a new throttle body looks like, and a rant about it.

Personally I think the entire Gen 2 throttle body design is goofy as hell. Why?

The throttle body in a Gen2 Prius is pretty much the same throttle body as the 1st generation, and of a somewhat similar design as the one used on the 1997 JDM version that never made it to the US.

I believe it's Toyota's first ever electronic throttle body, and by that, I mean no cable between the throttle pedal and throttle body.

The 1998 Lexus GS300, SC300 and SC400 had a somewhat similar setup, with a similar looking throttle control motor, but the linkage from the gas pedal to the throttle body was still a cable. I believe the motor was used for "fine idle adjustment" and perhaps cruise control (not a Lexus expert).

But there is a fault. A pretty bad one.

For starters, the 2nd gen Prius didn't really receive much of a redesign in that department over it's predecessor. If you look at both throttle bodies, there is a multitude of adjustment points. The most critical being the throttle position sensor itself.



But you can't adjust it. Sure, you can loosen the screws and wiggle it, but it will ruin the readout sent to the ECM. The only way to adjust it, that I know of, is using Toyota's proprietary software Dealer Tech's use.

As far as I know, the ECM will "relearn" things, but it has to be within the scope of a certain range.

Even worse, if the throttle position sensor is worn out, you will be "chasing ghosts" trying to get it all to link up. In fact, that's what happened to mine. I know the sensor is a solid state design with no wearable electronic parts, but resistors and things can drift over time.

There are other adjustments as well, the two throttle "stops". You can see them here:
1 on the left marked with yellow paint, and one on the right above the little pipe.



If someone who owned the car before you fiddled with them, it too can cause problems.

Again, all in all a very idiotic design. Why make an adjustable TPS on something that isn't adjustable to most mechanics without Toyota Techstream?


But here is where it gets interesting. Around 2003, Toyota went to a fully non adjustable design on some of their models. The throttle position sensor and motor incorporated into the same shell and used the same connector.

Here is a throttle body of a 2003 Land Cruiser:



Here is one off a 2004 Corolla:



No adjustments AT ALL. Not at the throttle plate, not at the TPS.

Now by Gen3 (2010) Toyota switched to the 1.8 engine, and it was finally given the non-adjustable throttle body.

Sorry for the rant, it just makes little sense. Toyota obviously had the tech to make a upgraded design for the Gen2 throttle body, as evident from the 03 Land Cruiser.

The Gen2 Prius throttle body seems more like a prototype. Like they put all those adjustment points to refine it, but never made a new design out of it.

The Hybrid system wasn't new. The 1997 Prius debuted in Japan 7 years prior to the introduction of the Gen2.

The adjustments aren't needed due to a hybrid power train, as made evident by the non-adjustable throttle body on Gen3 Prius and the earlier 2005 debut of the Highlander Hybrid and later Camry Hybrid.

When you think about it, the Prius for many years was Toyota's leader in innovation. It would be interesting to interview some of the Gen2 engineers and try to figure out what the hell was up with the throttle body. The only thing I can think of, is maybe for whatever reason their was no time to switch the tooling to make a new design of throttle body for the Gen2, so they just reused the same tooling and parts from the Gen1.

Again, it would make sense if these adjustment points existed because over time you NEED to adjust them, but you don't.