I was bored and decided to poke around. Powered the scheme from lab supply and looked at DATA pin with logic analyzer. It turned out the scheme reacts to all buttons but "Unlock". Found one bad transistor, took a good one from donor pcb. That fixed the reaction to "Unlock", but the fob still didn't work overall.draser wrote:True, provided the carrier frequency is the same for all cars.
Next there was at least one short ceramic capacitor. Resoldered all 4 from donor. Didn't work. I don't know why did that, since the main HCS chip didn't work on a good donor pcb
Oh well, maybe, donor was dead as well.So now I'm more or less sure the circuitry is Ok, besides RF chip, which I can't check without RF counter.