I thought I'd post me experience with repairing a key for a commodore. The key I repaired is for a VX, but I understand that the VS, VT, VX, VZ, VY are all similar.
What prompted this repair was that one of my car keys stopped working one morning. I figured that it had a flat battery. However, these keys are not designed to be repaired or have their battery replaced. Replacements cost about $80 plus.
With nothing to loose, I thought I'd have a go at a repair.
Note: I actually repaired two keys using two different battery replacements and two different ways of fixing the case.
Battery replacement - Jaycar battery (cost $2.45)
I'll start with how to replace the battery using a battery available from Jaycar.
Here is how it starts off:
Remove the two screws and separate the key blade from the transponder
The transponder is glued together and the two shells have to be broken apart. Start by inserting a broad flat-blade screwdriver in the slot that held the key blade and carefully lever it until the glue starts to crack.
Carefully keep the cracking going by progressively moving the screwdriver around the body as the crack opens. DON'T push the screwdriver in to the body of the transponder or else you may damage the circuit board inside.
The two halves will separate.
The nearest battery that is available from Jaycar is this one. Cat No. SB1762. It is a CR2032 intended for vertical circuit board mounting. We really need a horizontal one, but this one at least has tabs.
The old battery can be seen on the board. The new battery is in the foreground.
To remove the old battery, wedge a small screwdriver under it to provide a little upward pressure (but not too much).
Turn the board over and heat the two solder tabs one at a time and "walk" the battery up and out of the board. It is best not to try and fully free it side on one go, but rather just bring each side up a millimetre (or so) at a time.
Now we need to somehow make the replacement battery fit the horizontal mounting holes. Here is how I did it. Firstly, I bent the large tab on the positive side fully back on itself. See the lower battery.
The negative side is very easy. Just carefully bend the tab. See the lower battery again.
To complete the positive terminal, I carefully broke part of the positive tab from the old battery. DON'T tear the spot welds as the case may rupture - and lithium burns spontaneously in air! I have soldered the battery in by the negative terminal here too.
I found that I could make the old positive tab sit neatly into the new battery. I have chopped one of the 'pins' off the new battery as it was too close to the switch.
Things got a little messy here. I initially tried to simply solder the old tab to the new tab. The tab wouldn't plate very well with standard solder. I thought I'd try bend the remaining pin towards the old tab and try soldering that. It sort of worked, but it wasn't very strong.
To bridge the tinned bits of the two tabs, I thought I'd use some wire instead. I started by stripping a piece of wire.
And then soldering it across the tabs.
And then trimming it.
You will need to trim off the negative tab on the solder side of the circuit as it will protrude too far and will not allow the case to go back together. This completes the "Jaycar" battery replacement.
Battery replacement - Element14 battery (cost ~$3.50)
If you are prepared to spend a little time and a little more money, you can source yourself a 'horizontal' mount battery that will 'drop in'. I purchased a Cat No. 129-8346 from Element14. I got three batteries for a whisker over $10 with trade discount. Expect to pay about $3.50 plus delivery (~$10).
Here is another key with the better fitting battery.
Opening the case and removing the board is as before. These things are like walnuts - some are easy to open, some are hard. this one was hard.
"Walk" the battery out of the board by carefully applying pressure while heating each pin with a soldering iron.
Install the new battery. You might need to "walk" it down if you haven't got the right gear to clean off the old solder. Make sure you put it in the right way around. Don't even 'touch' it in the wrong way - it will probably damage the board.
The tabs will protrude from the underside of the board.
Carefully trim them off.
The battery replacement "element14" is complete.
Reassembling the case
Test your transponder. You should be able to lock and unlock the car using the bare transponder board. If you are happy it is working, you can reassemble the case.
If you are happy the case is in reasonable condition, you can simply throw away the gasket and glue the case back together. You will then need to reinstall the key blade and you're done.
If the case is broken or the buttons have gone (like this one).
I thought I'd try a new 'screw together case' I sourced via ebay.
in goes the circuit board...
Screw the case together...
Refit the blade, and done!
Getting the case to go back together and have the buttons work can be fiddly. With the screw-together case, I had the glue the buttons on to stop them coming out.
I'm also going to try some other cases from ebay to see if they are better or not.
What the hell has this got to do with renovation????