How to add SKS to the hatch and passenger door on a 1 door SKS Gen III Prius

I am proud to present the complete writeup for adding the SKS sensors and antenna to the passenger door and rear hatch on a Prius that originally came with 1 door SKS. For a bit over $300 and a few hours of your time you can get pretty close to the same functionality as the factory installed 3 door SKS system.

This took me about 4 hours to do and some of that time was spent taking pictures and figuring out how to install and connect things, so I expect that if you're comfortable taking apart your car and connecting wires that this could probably be done in 3 hours or less... if you're a bit less comfortable with that then it can still be done, but you may be looking at more like 4 or 5 hours. There's nothing really terribly complicated here... just a lot of steps.

Also, I know there were a few people looking at adding SKS to the rear passenger doors on a car that already had 3 door SKS. I think this will definitely be possible and you should be able to glean most of the info you need from this document. If you want to try that, let me know and I can provide a few other tips.

Finally, many thanks to a number of people that contributed on this thread.... http://priuschat.com/forums/gen-iii...ding-smartkey-door-handle-rear-pass-side.html, especially pEEf who contributed quite a bit without any gain for himself... he doesn't even have a Gen III Prius, as I understand it.

If you see any errors in the guide or you attempt this yourself and get stuck, please let me know and I'll try to make things a bit more clear.

Actually, if you attempt this yourself, let me know how it goes even if it does go well... I'll be happy to know that spending the extra time documenting my install and writing this guide has actually been helpful for someone.

Brett

 

Technically it may be possible, but I would hesitate before doing it on a car that was deisgned for 1 door SKS... that would be connecting 5 antennas and 4 touch sensors to a system that was originally designed to handle 1. I'm not sure if you'd have much antenna range and I'd be afraid that the touch sensors may draw too much current and cause a problem.

However, if you have a car that originally came with three door SKS then adding the two rear doors by piggybacking them off of the two front door connections should certainly be possible and safe.

 

If you look at the first page of the document you will no longer be curious

Brett

 

That's an interesting thought, but honestly I don't know how much of a difference it would make. Toyota definitely does use unshielded wire and I suspect that most of the range loss is not due to the wire, but rather the fact that we're connecting three antennas to a system that was designed for one and the fact that doing so results in an impedance change. The original 3 door SKS system has three seperate circuits for the antennas.

It certainly won't hurt to try and you might gain a bit by using coax, but I question whether it will be significant.

Good luck either way,
Brett

 

Glad to hear it's working for you. Maybe I need to revise my time estimate a bit. It was hard for me to tell because I did the project over several days and stopped to take pictures and such, but I had thought that it could be done in a bit less time than it took you.

I saw this once or twice over the past few weeks since I did this mod and I wasn't sure if it was a result of the mod of it it was always that way, but this certainly suggests that it is a result of the decreased range. Maybe I just normally approach my doors a bit slower so I see it less frequently

This is definitely true and a portable soldering iron could have been handy. I did the entire thing with wire taps and frankly I would have been worried about soldering some of the connections in such tight spaces because I'd be afraid of dripping solder or burning something with the iron. But each to their own and whatever works for you is the best option.

I agree here... there's not much extra wire to tap into and it's much easier to just cut off the connector. No matter what you use here, though, make sure it's weatherproof as these connections wind up under the bumper on the outside of the car.

Speaking of which, did you pull the whole bumper or just pry back the top like I did?

It really is and even after doing it twice (once for the mod and once on the drivers side when I was testing) I really don't have any good tips for getting it back there... you've just got to keep working at it and eventually it'll fall into place.

I didn't really have any trouble removing the plug from the outside, but this seems like a good idea if you do have trouble.

There is very little space to work with up there. The other option
is to try to run your wire through the rubber tube into the hatch and tap into the green wire within the hatch, but that still requires lowering the headliner a bit and also removing more trim from the hatch. As much of as pain as it is I think doing the tap in the headliner is the least difficult option.

Good idea. I may buy some myself and install it next time I feel like disassembling something

I guess I didn't mention it in the document, but I unplugged everything before I did my wire taps as well... that way you can move the wires into a little better position and get some slack as well.

True... plus, of everything you need to do, removing the glove box is one of the easiest

I never even noticed the second gray wire. When I get a few minutes I'll try to update the doc to make it a bit more clear about exactly which wire needs to be tapped.

Thanks again for your thoughts... I'm sure they'll help the next ones who dare to take this on

Brett