Defective key card

The key card of my ZOE was slowly giving me trouble (not the keyless entry one BTW, it’s a simple ZOE Life).

It was slightly iffy for a few weeks, but nothing that a bang couldn’t fix. However yesterday I could almost not start her while away from home. As significant other has another good working card, I decided it was worth to give it a tinker treatment. Unfortunately it is friction welded together and carefully cutting it open along the sides was not enough. Unreasonable force (for the un-initiated, bigclive.com) using spudger and chisel was to be applied.

Remote control antenna and chip is top left, transponder for the slot top right. It’s a flat, probably ferrite brittle core, with hair-thin exposed copper wire wound around it. That thing had come off. The problem probably was a somewhat dry solder joint that had gone bad under regular stress and making an iffy contact. I assume it broke off completely under said unreasonable force. Long story short, I soldered it back on the PCB using leaded solder and put it back together. For now with Scotch tape to make sure it works again, which it seems to do indeed. I will carefully glue it shut again if it keeps up a few more days.

Bottom line: if you decide to open this thing up, be very careful when cutting around that coil area, and be prepared to use quite a bit of close-to-destructive force just below the open/close button pair and around the coin cell area, all to be applied carefully with a blunt chisel tool not to kill the thing. At least you now have a layout.