If it's got a "reset" slot, then it also has an interlock system designed
primarily for prevent morons from confusing the pedals and claiming
unintended acceleration when they drive into a tree while pushing the gas
pedal as hard as they can.

There's three parts: sensors, logic, and actuators.  The first most
important sensor is the brake pedal.  I dunno about what other sensors there
may be.  Unless the system thinks you have your foot on the brakes, it won't
let you put the car in gear!  The logic may be burried inside the engine
control computer, transmission control computer, or perhaps a security
system, or interior lighting logic black box.  Last is the actuator right in
the vicinity of the "reset slot" that lets you put the car into gear.  Check
that it's getting voltage and that it can move freely.

I end up reposting this every winter.  Here is what you need to know.
Keep in mind that this was originally written some years ago so the
prices may be out of date and the old Internet source is out of
business.  

(begin repost)

My friend purchased a (transmission) console switch from
[hparts.com but they are out of business and the current web site is a
new operation and new owner].  The part is Honda# 35700-SM4-A91  and
the price was $31.63 plus $5.62 S&H.  She had a very experienced
amateur install it.  He looked at the manual briefly then went out and
installed it in under 20 minutes. It should be pretty straight forward
for anyone with just a little experience, only slightly tricky part is
to adjust it (if necessary) so that the indicator lights match the
shift lever position.

Results:  In three days of use at temperatures down to -3 F she has
not had any trouble.  Previously the car would always experience the
syndrome until it had been warmed up for at least 20 minutes on even a
moderately cold day.

To recap the symptoms:

- Vehicle is 1990+ Accord with AT (others may be affected also)
- Problem is strongly linked to cold temperatures.
- Key cannot be removed after shifting into P
- Dash indicator light does not indicate "P" even though transmission
lever is positively in P
- Car cannot be shifted out of P after this has happened
- Problem solves itself when the "P" indicator lights which occurs
after a period of time related to the interior temperature of the car.