EV Mod kit in 2022.

With an older Prius it may not be a good idea since the could stress out the hybrid battery. You might be fine if it is just to back out of the driveway or move short distances. In my experience in a 2008 even just running your car in Neutral will tend to send a warning for the hybrid battery protection as it doesn't charge in Neutral, but does in Park.

Here is a DIY tutorial:
http://www.eaa-phev.org/wiki/images/0/09/Prius-evbutton-install.pdf

Here may be a place still selling a kit for $30:
Ev (Electric Vehicle) Mode switch for Prius 2004 - 2009

 

duplicate post

 

any on ebay or craigs list?

 

I did this mod several years ago on my 2005. As noted, it's not terribly useful, but it is clever and sometimes it's nice to be able to move the car to another parking spot without the ICE coming on.

The author of the instructions used a two conductor wire (as I did in my project), running the wire from the push button to the ECU so both connections are on the ECU plug. You could run a single wire to the ECU and a different one to a good ground near the push button, but it's cleaner and might be more reliable to have that ground point close to what you're grounding to prevent any loose ground conductivity between the ECU and the remote ground point from keeping the button from pulling pin 27 all the way to zero volts.

One more thing; I didn't have an anti-bounce push button so used a regular momentary contact push button. Quite often, it didn't work because the contacts would bounce and the car would see it as two pushes on the button instead of one. Your best results will be with an anti-bounce button.

And remember that driving in EV will reduce your MPG and the lifetime of your hybrid battery. Use it only for moving the car a few feet without running the ICE.

 

I did a little Googling and could not find a switch for sale that has built-in de-bouncing. But a simple RC circuit can filter out the bounces.
https://www.allaboutcircuits.com/technical-articles/switch-bounce-how-to-deal-with-it/

There are lots of other articles on switch bounce and some have pretty sophisticated circuits.

 

Wow, I would've thought that there would be a number of no-bounch switches for sale. Especially with all of the Raspberry-Pi and Arduino microcontrollers development systems out there. Btw, the ~$50 Raspberry-Pi boards can run Linux (what Android and Apple are based on), and even Windows (since it's an ARM processor - like the ones used in cell phones, Chrome-books).

Here is a switch no-bounce switch (/circuit) that is ~$15 with S&H:
https://www.logiswitch.com/shop/nobounce-switches/pushbutton-switches/ls-6-s/?attribute_color=Red

LS-6-S 6mm NoBounce Pushbutton Switch – Screw Terminal Connector
$7.30
Comes with three separate clean, debounced outputs, including two momentary selections: Normally High (low when pressed) or Normally Low/Handshake NL/HS (high when pressed) (see User Guide) and a Toggle (push on-push off) output. Toggle changes state each time the switch is actuated.



I would not recommend using a simple "RC" circuit.
There are many issues that can happen with an output like that.
I doubt that the input to the controller is specifically designed to handle an "analog" input. With the slow rise time of an "RC" circuit, the time that the voltage is between "on" and "off" voltages is "massively long" (in circuit terms). That can/does cause high currents on the input buffer. Over time, the input buffer will fail.
How long? Hard to say. Maybe the first time, maybe it'll last for millions of cycles. Imho, it's similar to asking how long a tire low on pressure will last - literally hundreds of factors.


I'm still surprised that I couldn't find a lot of these types of switches/circuits available from China.


Here seems like a decent quick look through:
Debouncing Contacts and Switches

Imho, the following graph of test results using various switches is likely the most useful thing for non-techies:
http://www.ganssle.com/images/debouncetimes.jpg



Good Luck!

 

Thanks. I missed that one. They do seem to be few & far between.

 

No, the ECU is looking for a momentary contact closure. Just a pulse from the 12V on pin 27 to the 0V on pin one. As soon as you release, it needs to return to 12V. Then, to take it out of EV, do the same thing.