Interestingly, both key fobs I got with the car would operate the trunk/boot and the headlights, but wouldn't arm/disarm/lock/unlock the car.

I checked the little door in the ignition switch and lubricated it with graphite based lock lubricant, and behold! the steering column started returning to the "park" position when I removed the key but still no remote lock/unlock.

On the suggestion in another post I opened one of the key fobs to check the graphite pads but my remote actually has four surface mount micro switches. And the lock/unlock ones were yellow where the light/trunk pair were silver. Further invention got a nice crisp action on the silver ones, and no movement on the yellow ones. This was because someone (PO?) must have left the fobs in a puddle of cola, and gummed the two switches so they wouldn't move. Further evidence was a sticky residue on the back of the actual rubber key membrane.

To fix I put the circuit board in a very small baggie and added a generous squirt of WD40. As I massaged the offending switches I began to feel movement. Remove the circuit board, blow it off with compressed air paying special attention to the actual switches and repeat the process in the baggie with the WD40. Repeat until the switches all "click" nicely when pressed. Wash the circuit board off with rubbing alcohol and blow dry with compressed air. Wash residue from inside the rubber membrane with alcohol, and blow that dry too. Reassemble the fob with a new battery and Richard's your Father's brother as they say.

I now have a working key fob and can remote lock/unlock the car, complete with that satisfying little chirp as the alarm arms.

I should have checked the fobs sooner, but made the mistake of ASSuming that because

1. Both fobs exhibited the same symptoms
2. Both fobs would pop the trunk/boot and turn the lights on
3. I had replaced both fob batteries

the issue was not with the key fobs themselves.

Hopefully this might help someone else.

 

Nice investigative work and a good write-up!

 

Nice job, didnt you have to re-program the fobs though after taking the batteries out?

 

No - I didn't have to re-program. And the battery was out for a good 60+ minutes while I cleaned and dried the circuit board. I think on these units the fob is hard-coded with an electronic signature that the car "learns", and I believe the car uses a non-volatile memory to store that information. Therefore, once the fob is "coded" to the car it is almost permanent.

Which leads me to the question, has anyone been able to associate one key-fob with several cars at the same time? Just wondering......