If you have an XV10 (or other Toyota of the era) with a factory immobiliser, here’s a run through of replacing the soldered battery in the “sealed” immobiliser/keyless entry fob. My local Toyota dealership gave me a handful of faulty NOS units, to see if I could find a use for them. The plastic cases were useful to me, to re-shell one of my battered remotes from 1997.

Warning: Ensure that you are familiar with your programming procedure before doing this job, and make sure you have a spare working remote in case the worst happens!

First of all, order yourself some of these batteries, as many as you require depending on the number of the remotes.

https://console5.com/store/panasonic...nes-saves.html

Otherwise, you’ll need:
- A bench vice
- Your mum’s hairdryer (borrow it when she’s not home, then you can’t get yelled at)
- Some adhesive (pretty much anything with Selleys written on it will work)
- A soldering iron, some solder, and some de-soldering braid
- Painters tape
- A measurable amount of patience

Start by placing the remote in the vice, with some rubber or packing as not to damage the plastic too much, especially if you are re-using the case. Give the case a squeeze while applying some heat with a hairdryer, the seal will eventually pop and allow you to open the remote. Take your time with this step, as it will be a neater (and barely noticeable) reassembly if done properly.

Next, remove the circuit board, noting that the gasket and communications pins (if fitted) stay in their designated spots.

Then, de-solder the battery from the board, ensuring to take note of the polarity (positive terminal is closest to the button). Solder in the new cell, making sure that it is positioned correctly and will allow the case to close.

Now, mask up the remote in case of any skills with some painters tape, apply some glue (without gluing your fingers together) to the positions that were previously plastic welded, and apply some light pressure in the vice to aid in bonding. Wait a few hours, and that’s it!

Interestingly, the memory appears to be non-volatile, so the remote retained the programming without battery power, while I swapped the cells over. Ensure that you are familiar with your programming procedure before doing this job, and make sure you have a spare working remote in case the worst happens!

(Pictures coming)