Considering that a replacement smart key for a Prius can cost anywhere up to, and over $100, we’re going to show you a step-by-step guide on how to change the battery in one. If you have problems with yours, then this might be a good place to start. It's not guaranteed to fix your problems, but considering a new battery is much cheaper than a new key, it’s worth trying before investing in a new one.
What You’ll Need
Before you start taking things apart, there are a few things you’ll need. Firstly, the replacement battery. This is a 2032 button cell battery. Invest in a good brand, they do tend to last longer. And even though it isn’t too tricky to change, the less often you have to do this the better. A four-pack of these from Amazon will set you back just over $7.
Secondly, you’ll need a micro Phillips screwdriver. If you don’t have one, I recommend this kit from Amazon. It’s similar to a kit I bought for repairing iPhones and it has everything you need. The screwdrivers are magnetic, so the screws will attach to them. It makes the job a lot easier and the whole kit is less than $7.
Not really necessary, but incredibly useful is a magnetic tray. Use this for keeping the screws in. Again, you can get one from Amazon for around $7. You can use anything to keep the screws together, but I have in the past knocked dishes over and thrown screws everywhere, never to be seen again. Just a handy pointer.
Remove the key from the rest of the housing. To do this, slide the mechanism at the bottom to the left (with the key facing you and the Toyota logo the correct way around) and pull on the key. It should uncouple itself without any issues.
Now you need to remove the back covering to the smart key. This is the side with the Toyota logo. To do this, you again slide the mechanism at the bottom to the left whilst applying some pressure to the covering. It may take some effort depending on how old your key is. If you have trouble, there is a seam at the top, above the Toyota logo, where you can slide something to give you a bit more purchase. If you bought the screwdriver kit linked above, there are two plastic triangular tools designed for this purpose. If you didn’t, a credit card or guitar pick will do the job just as well. Make sure you don’t use anything metallic to pry it open as this will damage the plastic casing.
Once the casing is off, you have four screws to remove. Use the micro Phillips head screwdriver on this and remember to be gentle. The last thing you want to do now is to strip the heads of the screws. Once they’re removed, use a plastic tool, or small flat head screwdriver to lift the covering you took the screws from. It should come out with no real issues and reveal the battery.
Apply a slight amount of pressure to the old battery towards the flanged edge of the holder and it should protrude out. Remember to take note of which way the battery is facing so you fit the new one correctly. Take the old battery out, and slide the new one in place. Remember to put it in the correct way, the positive terminal should be facing out towards you.
Replace the plastic cover and the four screws on the internal housing. Don’t over-tighten the screws as this can cause damage or issues when you need to change the battery again. Put the outer casing (the one with the Toyota logo) back on. Slide it into place, and make sure to press the slide mechanism at the bottom to the left, this will make it click into place. Put the key back in place, again by sliding the mechanism to the left.
Check that it works by pressing one of the lock buttons. You should see a red LED blinking if it is.
Celebrate a job well done.