weak keyless entry-2004 Sonata LX

Lately sometimes when I hit the unlock button on the keyless entry
remote, I hear only a weak "thunk" and the doors remain locked. Normally
there's a loud "Thunk" and the doors are unlocked. I tried the other new
unused remote and it acts the same. Trip to Hyundai dealer? new remote
batteries?

 

If you hear the locks as you do, it indicates that the remote is working
fine. It's only a transmitter and the car either receives the signal or
it doesn't. If you press the unlock button more than once, as necessary
to unlock all the doors, do any of them unlock? If not, The problem may
be the battery in the car or a bad electrical connection or ground. If
only the driver's door fails to unlock, it's likely the actuator in that
door.

 

Thanks Brian. Your logic makes sense that the remote itself is good. My
remote doesn't work that way, it unlocks all the doors when you press it
once. Where is the receiver located in the car? Guess I could check
for bad grounds, etc.

 

The issue isn't likely to be the receiver either, since you can hear the
doors attempting to unlock. If there's a bad power or ground connection,
it must be in the actuating system. Since none of the doors unlock, it
seems like it must be a main connection of some sort or perhaps a bad
relay. You can view the electrical diagrams of the system on Hyundai's
WebTech site: http://www.hmaservice.com

 

Thanks for the good advice on troubleshooting my intermittent "weak"
keyless entry. It's been working normally for a few days now so I guess
maybe it fixed itself...for a while anyway. If it acts up again I'll
check some of the things you suggested.