2004 S model, 6 cylinder Key FOB works perfectly for 15 or 20 minutes after the car is switched off. Then it does not respond...as if it is dead. I have to use the key to open the door and the alarm sounds. I use the key to shut off the alarm Then the key FOB works great again.

Replaced the key FOB. That did not solve the problem.

Anyone have any ideas?

 

I don't know the answer but the first thing I'd want to look at is the cars battery voltage after engine shut off.
I'd check it at:
30 Seconds
5 minutes
10 minutes
15 minutes
20 minutes
25 minutes
30 minutes

Try to establish a trend and see if its (for some reason) loosing voltage.

 

+1

in case it drops, it may then cause the relevant module to go into power save and it then stops listening for a fob. (Usually this happens after a week or so and can be a surprise at the airport on return from a foreign holiday.)

 

I would also clean the internal circuitry of the key fob with electrical contact cleaner spray or just plain rubbing alcohol....

 

Sorry to ask a basic question.. you used a new battery right?

 

Many TSBs for locking faults.

bob