Every Toyota Prius that rolls off of the assembly line has the programming built into the computer to enable “EV” (”electric vehicle”) Mode. EV Mode tells the computer controlling the Prius to turn off the gas engine and use only its batteries until one of the following things happens:
- the batteries get too discharged (down to 2 bars on the Prius’ Energy display)
- the vehicle speed hits 35mph
- the driver asks for a lot of power (climbing a steep hill or getting onto the highway)
- the drive disengages EV Mode
When one of the above conditions is met the gasoline engine will turn on and the Prius will be out of EV Mode and back into its normal driving mode.
Because of reasons no one quite understands the Prius that you buy in the United States is missing the button on the dashboard to initiate EV Mode (but we all know that it’s somehow because of lawyers, right?). The computer in the US-market Prius knows what EV mode is and what it’s supposed to do when it’s in EV Mode — it’s just that there’s no way to tell the it that you want it to engage EV Mode. Unless you hack your Prius a bit.
I bought a kit from Coastal Electronic Technologies that uses the cruise control stalk to tell the Prius that you’d like to initiate EV Mode. Other people have figured out other solutions using normal momentary switches to accomplish the same result. I chose the cruise control solution because it seemed like an easy installation (it was) and because I didn’t want to have to install another switch onto my dashboard and run the wiring for the switch.
The kit came with very detailed instructions complete with plenty of pictures. The installation involves removing the glove compartment and installing a few wire taps into one of the harnesses which run behind there. The taps connect to the cruise control wires and to a spot on a connector where the EV switch would’ve connected if the people at the factory had installed it. Some people have reported problems getting the taps to make contact properly but I didn’t run into any such trouble. My total installation time was about 30 minutes.
Once the kit is installed you’ve joined the rest of the Prius-owning world and can initiate EV Mode by pulling the cruise control stalk towards you for 2 seconds. You’ll stay in EV mode until you disengage it (pull the cruise control stalk for 2 seconds again), until you meet one of the conditions mentioned above, or until you turn the car off.
I have to say that I installed the EV Mode kit because I thought it would be a fun gadget to play with but I find that it really is a useful thing to have. It’s nice to be able to pull the car out of the garage to park it outside or to drive from one store to another without having the gasoline engine start. And, when used in the right situations, it can improve the Prius’ already-fantastic gas mileage.
So, if you’re a Prius owner in the U.S. give EV Mode a shot. Think of it as installing optional standard equipment on your Prius.
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15 responses so far ↓
1 Thane // Jun 14, 2006 at 7:27 am
Very interesting. I understand how EV mode can help keep your fuel costs down. Thanks for sharing that.
2 Sam // Jan 15, 2008 at 1:47 pm
I’m thinking about doing the same. Just wondering if it will void my factory warranty if my Toyota dealer finds out during my regular maintenance services. Any thought? Thanks!
3 Ed // Jan 16, 2008 at 8:51 am
Hey, Sam,
That’s kind of a gray area. Some people say that you’ve voided the warranty because you’ve made some sort of change. Other people say that you really didn’t make a change, you just activated a feature which was already built into the car. Personally, the latter makes more sense to me.
I also don’t think I’ve ever heard of a dealer voiding the warranty because of the EV mode hack. Then again, I’m sure that if you have a dealer who is looking for a way to mess with you he could probably try that route.
I will say that I use my EV mode much more often than I thought I would, probably 2 or 3 times a day, so I’m glad that I went through the “operation”.
4 Alex // Mar 23, 2008 at 12:34 am
Hi. Thanks for your review. Can you tell what year is your Prius and what kit exactly did you buy from Coastal Electronics? Lockpick 1 or 3? Thanks!!
5 Lawrence // Apr 3, 2008 at 10:34 pm
I don’t have cruise control in my base model 2008 Prius. How do wire up the pushbuttons?
6 Brent // Apr 6, 2008 at 5:01 pm
What about a Canadian Prius? Any differences to know about? I heard there was a hack that can always tell the computer to leave the engine off until it hits 40kmh, true?
7 Ed // Apr 12, 2008 at 5:25 pm
Hey, guys,
Sorry that I didn’t get back to you sooner, but I’ve been out of the country for a few weeks.
Alex: I have a 2006 Prius and this is the URL to the kit I bought: http://www.coastaletech.com/electric_only_mode.htm
Lawrence: I’m not 100% sure but I would guess that you can’t use this kit without having CC. You can send an e-mail to Coastal Tech to be sure:
support@coastaletech.com
Brent: The URL I showed Alex says that it’s for the North American Prius, not just for the U.S. model. Still, I’d ask the guys at Coastal first to be sure. Oh, and this kit will tell indeed the computer to keep the gas engine off until certain conditions are met (see the post above).
8 Vince // May 15, 2008 at 9:58 am
Hi,
I installed the EV-mode kit from Coastal on my Canadian 2007 Prius and it works great. The Prius in Canada is the same as the one in the US.
And as far as I know, the basic Prius comes with Cruise Control since 2004. Look it up in your owner’s manual.
Problem with CoastalTech is that they won’t ship to Canada. They say it’s international and they won’t ship international. Tell me how that makes sense! I was pretty upset but I wanted the kit so bad that I had a friend in Georgia buy it for me and send it up.
Depending on battery charge and driving conditions, you can go between half a mile and 2 miles on the battery alone. Not much - but lots of fun. You can go to about 1/4 of the accelerator. The power in EV-mode is limited to about 28 hp (that’s 20 Kw - the maximum power output of the Prius battery).
Of course, this gadget makes you wish for more. I’d like to have more power and more range on EV-Mode. And be able to recharge the battery when I feel like it by plugging-in at home.
Guess what? People have converted their Prius to do just that! They’re called Plug-in Hybrid cars. Look up http://www.hymotion.com and http://www.calcars.org.
Have fun.
9 don m // May 16, 2008 at 3:16 pm
Im rebuilding a wreck so I don’t worry about warranties
10 Bobbe Ruch // Jul 7, 2008 at 1:18 pm
Hello,
I just bought an Electric Mode Kit for my 2007 Prius. Do you know of any certified mechanic who can install it? I live in San Jose, California. HELP!!!
Thanks,
Bobbe
11 Ed // Jul 14, 2008 at 12:03 pm
Hi, Bobbe.
It’s really not a very hard to do but it can be a bit nerve-rattling to take apart part of the dash. I don’t know if you’ll be able to find a mechanic who will do it “officially” since it’s not really a Toyota-sanctioned procedure but I’m sure that you can find someone who can help you out with it. You may even be able to find a mechanic to help you with it “on the side”.
Good luck,
Ed
12 Vince // Jul 17, 2008 at 9:59 am
There’s a guy who made a video of how to install the Coastal kit. You can watch it here: http://video.google.com/videoplay?docid=5377826536782014996
I found it helpful and a good complement to the paper instructions that come with the kit. It gave me the confidence to do it myself. It took me about 45 minutes and I went very slowly checking everything at least twice.
Good luck.
Vince.
13 Ed // Jul 28, 2008 at 11:19 am
Hey, Vince,
Thanks for that link. The procedure really is as easy as the video makes it out to be, but it’s always nice to actually see the steps in addition to reading about them from an instruction sheet. Nice find!
Ed
14 billtech // Sep 25, 2008 at 12:07 pm
Interesting.
I am an automotive tech, deemed Master Tech by my peers before ASE testing was available. I also have a background in electronics, as a hobby.
I own my own auto repair business, since 1985, and want to relate some things that need to be known.
1. The batteries used in the Prius are able to maintain steady voltage & therefore power output at a steady rate, but then this voltage/power drops off suddenly. As opposed to most batteries, which gradually lose voltage & power over a longer period of time.
2. Toyota, with the intention, I am told, of optimizing the LIFE of the battery, chose to maintain the charge level of these batteries at anywhere between 40% and 60% charged, and NO more.
This puts it in that critical point, in my opinion, where it is always suddenly dropping. this is why it will only go at maximum, about 2 miles on batteries alone.
3. In any circuit (or powertrain, in this case), when voltage drops, amperage will rise, which can damage wiring in motors not designed for that higher amperage.
4. One of my customers found out about this when his car ran out of gas, and he drove it on battery power alone, less than 2 miles, at which time, the car died, was very difficult to start when he did fill the gas tank, AND he now found he had a loud whining noise from the left front.
5. This turned out to be, diagnosed by the dealer, as a burned drive motor, requiring a new transmission. Estimate to fix was $7600. In this case, after some difficulty sorting out the details, was finally covered under warranty.
So, I have thought about some alternatives, but the bottom line is:
Be cautious when modifying or altering this particular hybrid, due to the vulnerability of the system described above.
15 Randy Richards // Nov 4, 2008 at 5:10 am
Hi, Does anyone know where the video http://video.google.com/videoplay?docid=5377826536782014996 went to? I’d like to figure out how to access it.
THanks
Randy
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