Last night I tried to follow these instructions, which appear to be the most commonly used: http://www.calcars.org/prius-evbutton-install.pdf To make a long story short, they want you to pull an unused pin out of an unrelated connector in order to add a new wire into a the end of the wire-harness for the hybrid ECU. The trouble is, the pins are not the same. In fact, they aren't even the same brand, one is an AMP and the other is like Molex, I think. The pins are similar in shape and size and it will go in 3/4 of the way before it sticks on something. I could have probably forced it in, but it certainly didn't want to go in like it was supposed to. At first I thought maybe it was just my car that was different, but after careful examination of the close-up photos in the install guide, I would say they are wrong on there too. Again, I could have forced it in, but it might have destroyed the connector and/or might have never come back out again. So I opted to wait and my friend at the Toyota dealership is going to get me the correct pin to use for that particular wire harness. Just FYI to anyone trying to use that guide.
Using the standard molex mating connector from any computer cable (like internal headers that use 2.54mm/0.1" spacings) you can pop the pin out and use. Since you seem to know about electronics (spotting the difference in molex vs. amp), why did you buy the mod? Any radioshack button and copper string would do the trick and give more functionality. I just assumed it was "the masses" that bought the calcars version... Good luck
Your profile says you have a 2002, a different model than the 2004-2009 the instructions are for. I suspect that may have a lot to do with it. I had no problem using those instructions for my 2005.
I didn't buy any mod, these instructions are for doing it yourself. I actually bought a nice pushbutton switch from radioshack and wired it all myself. That is what the instructions are for. But, the pin in the AMP connector aren't exactly easy to find at your local radioshack. That is why they suggest pulling it from this other connector in the car where there are extras...except they aren't the right kind. Actually, I just bought a 2008 Prius this weekend and that is the one I am wiring up. The 2002 doesn't have an EV mode, so there is no way to wire up a switch, one of the reasons I decided to upgrade.
Hmm, I don't know then. My installation was done too long ago and my memory too foggy to think where your issue may lie, other than to say the pin is a tight fit in the ECU plug. Now that I think about it, I did vary the approach of the CalCars instructions slightly there; I used needle-nose pliers to get the pin in, as described here. Congratulations on the new(er) car!
Well, I finished the install last night. I managed to find an old toyota wire harness that used the same pins and chopped one of the wires out and spliced it in for my EV button. To my surprise, I thought the button wasn't working at first. I had been told it would make a beep on the dash when pressed. So I'd hit the power button and then the EV button several times but the engine would start as normal and nothing would happen. Eventually I discovered that I was turning it into EV mode and right back out again. I quickly discovered the car can not go very far, which I already knew but I had heard people say they had driven up to 2 miles in this mode. I was only able to drive about 1/4 of a mile. Granted, by battery was only showing 4 bars. I tried again later on a downhill slope with 6 bars and managed to go an entire mile. But I was coasting a good portion of that. Still, in a few weeks I'll have a plug-in kit and the button will be far more useful.
Regarding the pin. You are correct, it is slightly different, but most people use it anyway for simplicity and cost. Notice that the price of the correct pin is $15. Here's a post I saw on a PHEV forum that explains how to get the correct pin:
