Sometimes when the weather is cold or damp, or I haven't driven the car very far before I park, the red square around the"P" doesn't light up and I can't turn the ignition key enough to remove it (even with the break pedal depressed). Also, sometimes when I start the car, the "P" isn't lit up and I can't get the car out of park even with the brake depressed unless I use the shift lock release (I keep a spare uncut key in the car for this because it is really annoying!)

Sometimes if I wait a few minutes, the light comes on, but sometimes not....

This doesn't seem to happen when the weather is warmer and drier but I live in the north west so that kind of weather only happens for about 3 months of the year.

I haven't figured out if this is an electrical or mechanical problem. The car is 18 years old and things are wearing out.....

Can anybody help?

 

That sounds like an electrical problem since you can still use the mechanical release. Also, with my 99 accord when I was messing with the steering wheel and ignition switch I was unable to get the key out if power was disconnected. I would get the electrical troubleshooting book and service manual for your car and start testing. You might be able to find them at the library. You will probably have to replace an electrical switch or two. Heat and moisture eventually affect the contacts inside the switch and cause them to sporadically fail.