Lately I've gotten lucky at some local LKQ yards and picked enough parts from a D1 to either replace some things on mine or sell to support the habit. On my last visit, I grabbed a key and remote fob still in the ignition, figuring I could use the fob. I did the same with new blank keys and my LAUNCH tool on my D2. Many times I find myself asking whether something can simply be done and scouring forums for my specific problem. This one was a bit of an odd duck so I thought I'd share it here in case anyone else comes into the situation.

The fob in question was the Lucas 3TXB remote. Upon inspection it appeared to have some corrosion from the old battery. I pulled that and cleaned in IPA. Without an LED on the board, though, I couldn't tell if it was working. I have a couple of radio antennas and USB adapters for some other things around the house (FlightAware, reading smart meters for home automation, etc) and tried using the command-line tools for RTLAMR to see if the thing was producng a signal. I knew it had to be either 315 or 433 MHz. Tried both, no results. Tried the same with my working D2 key fob. No results either.
So then I read that the burst is so short, some sniffers won't pick it up. I found another Linux-based radio sniffer called URH, installed it, and set to 433 MHz. Nothing. Then I tried 315 MHz. Success! Both my D1 and D2 fobs operate at 315 MHz. I confirmed this when looking up the FCC ID of the D1 fob.

Next step...program in the LAUNCH tool. I got to the Alarm/Security menu, told it to learn a new Plip, and followed the instructions. Success again. Cleaned up the fob housing and now my D1 that once had a fob has one again.

PSA: be careful going to self-service junkyards. I like going to antique shops and it triggered my antique bug. Now I'm getting alerts anytime a D1, D2, or P38 RR rolls into a local yard.