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Everything You Ever Wanted To Know About Throttle By Wire

Posted in General, Mechanics, Recalls, Toyota by Kurt Ernst | February 26th, 2010 | 2 Responses |

I’m not aware of a vehicle sold in the US today that doesn’t use throttle by wire technology. What is it? The videos below will explain that in as much detail as you could possibly want. To briefly describe it, throttle by wire uses sensors and motors to open and close the fuel injection’s throttle body. Previously, on both carbureted and fuel injected motors, this was done via a cable linkage between the accelerator and the carburetor or throttle body. Why go to throttle by wire? Theoretically at least, it’s more reliable, more precise and allows greater monitoring capabilities of emission control systems and engine performance.

Where did throttle by wire originate? In aircraft, where it was originally called “fly by wire”. As any DC3 pilot will tell you, muscling a big plane with cable activated ailerons, elevators and rudder takes some strength and endurance. As planes got bigger, heavier and faster, it became necessary to develop flight controls that used servo motors to do the hard work.

So if they’re used in aircraft, where safety is paramount, they should be bulletproof in other applications, right? The car manufacturers, Toyota especially, would like you to believe that. I have a friend who’s a flight control engineer on military aircraft, and he’s less than convinced. In his words:

“ To be honest, I’ve always thought it to be the height of arrogance by the car companies when they claim that (failure) COULDN’T be electronic. I work with aircraft flight controls. We use quad redundant electronic systems (when you take into account internal modeling, it is more like 8x redundancy) and monitor hundreds of parameters in clock cycles measuring in ms. We STILL get cases where we have failures that cause strangeneess in the air and our fleet is measured at around 1500 aircraft.

Take a car, with far less rigorous maintenance, working on a dual redundant system and tens, if not hundreds, of thousands of copies and I’d be shocked if there weren’t annunciated electrical failures.”

In any case, here are the videos, courtesy of Toyota. While produced by Toyota, they’re still relevant to other manufacturers, who use the same technology, albeit with slightly different hardware and software. Hat tip to Brad for the heads up on the videos.

Electronic Throttle Control Overview

Electronic Throttle Control System Animation

Electronic Throttle Control System Animation: Diagnosis

Electronic Throttle Control System Animation: What If?

Still have questions? Still want answers from Toyota? The following webinar, source of the above videos, was held on February 22. It goes into a bit more detail about Toyota’s testing process to counter RF and EM interference, and includes a Q&A session with the press. It’s about an hour in length, so make sure your coffee cup is full before you hit play.

Toyota Throttle Control System Webinar

Source: Toyota

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2 Responses

  1. Elizabeth says:

    I think that Toyota should be responsible for inspecting vehicles related to the malfunction of the trottle body. How accurate is a diagnostic machine? Can an electronic malfunction read incorrectly if it is damaged? What other methods of testing are available through Toyota? Safety should be a priorty! I own a 2001 Toyota 4Runner and I have been advised to replace the entired Trottle body due to a malfuntion. The cost $1500.00 and toyota can not guarnteed that will fix the problem. Toyota is relying on diagnostic machines, but how reliable are these diagnostic machines? It is extremely costly for the consumer.

  2. Kurt says:

    First, don’t confuse throttle by wire with throttle assembly components. If I remember correctly, Toyota was using a conventional, cable actuated throttle on 1991 4Runners, so your issue isn’t at all related to Toyota’s current troubles.

    Parts wear out, especially on a truck that is nearly ten years old. How many miles are on it? Has it ever been submersed in water?

    That said, $1,500 for a throttle body replacement sounds steep to me, especially if the dealer isn’t sure that it will fix the problem. My advice would be to find another dealer and get a second opinion.