TRW Keyless Entry module

[White93z34]

Basically the 2 big ICs are the biggest areas of concern.

For me over the long run reflowing the joints is a temporary fix, I've had more success in adding some good solder. Recently I've purchased a proper desoldering tool and I'll just clean out the solder and start over with fresh

[GnatGoSplat]

I originally did the 2 ICs, but then had to do it again not too long after (can't remember if months or years).  So I ended up just reflowing every single joint and that kept it working well over a decade.  I added flux to every joint and added a little new solder, but I didn't remove any old solder.  If you plan to desolder first, then I'd recommend finding vintage 60/40 solder (with lead).  If all you can get is RoHS solder, then it'd be a good idea to keep the old solder as it still has lead.  Leadless RoHS solder are famous for solder joints going bad over time.

Checking the caps is a good idea.  I didn't do that at the time, but I've had to change out enough electrolytic caps to know they have a finite life.