Prius EV Switch

And now for something totally different:

I installed an Electric Vehicle switch into my Toyota Prius!  For some reason, even though this ability to switch one’s Prius into a mode where only the electric motor is used is a standard feature in the Japanese and European edition of the car, it was removed from the US edition.  Thousands of American Prius owners have questioned this decision by Toyota, and started to seek ways to overcome this crippling limitation.  And of course, where there’s a will, there’s a way.

Here’s my pristine dashboard on the passenger’s side, before the dangerous operation.

Here’s the dash again, with the side air conditioner panel removed, and glove compartments gutted.  See the onboard computer starting to peek out?

98% of Prius owners will probably never get to see the guts of their car.  It’s not the most comfortable thing to see when you have no idea what you’re doing.

You can see that the A/C grill really isn’t very sophisticated, especially when compared with all those wires behind it.  Now do I snip the red wire, or the blue wire?

This is the unimposing EV switch-enabling circuit board that I had to splice into the car’s computer connections.  I honestly don’t really know what it does, so for all I know, it’s stealing my identity and sending it back to its home base.  Oh well.

This is the bundle of cables with the wiretaps in place, after I finally managed to snap the bundle connector back into the main computer assembly.  After about five minutes of tinkering, I had started to get worried when I was having trouble plugging everything back into its appropriate slot.

This is the gash I gave myself when I got too hasty trying to coax a cable lead into a tight slot.  The little red thing in the photo is a sample of the two wiretaps I had to install in the onboard circuitry.  I already broke the spare one accidentally, so this served as a backup in case I destroyed another wiretap with my bare hands.

This is the moldy rotten shrunken apple pear that I discovered under the driver’s seat when I dropped my screwdriver and had to feel around down there.  “Hmm.. that doesn’t feel like a screwdriver…”  This had to be from last summer, when I was picking apple pears with Steph and her mom in their backyard.

This is the bike I absentmindedly backed into in my excitement to try out my new EV switch.  The EV mode worked!  The bike still worked too!  Note to self: Never park your bike behind your car, especially if you don’t have the 2006 Toyota Prius, which at least has a rear view camera.

Well, that was a fun one hour activity!  What else should I mod next?

  1. nice DIY!  congrats!

  2. that only took you an hour? awesome!

  3. man that’s some seriuos DIY project! ur next one should be installing a rear view camera on ur prius! 😉

  4. whoaa you DID install the switch. good job… but after reading your post, i feel like my initial safety concerns are even more legitimate. the crazy wiring inside a prius evokes mental images of a bomb.
    and… you might not have a rearview camera but you DO have three rearview mirrors 🙂

  5. Oy.  Nice job.  Does it work?

    But you shouldn’t post pics of your real license plate number online.  Leaves it open to hostile web-surfers.

  6. man, you sure had guts to tinker with the insides of your car!  how fun, though! =)

  7. Did your switch just close the circuit between the two wires?  I’d like to do it too but what reference did you use?  I don’t want to damage the vehicle electronics.  Great post though, thanks & regards, John

  8. For those who are interested:

    I bought the EV switch described at

    It works great! By default, the EV mode is off until you activate it. I don’t use it a whole lot, but it’s great for the occasional demo or when I need to be extra quiet. I didn’t buy a physical switch. It’s just activated with the cruise control stem.

    Good luck on your own mods!

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