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?
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Bob wrote:

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.
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Brian Nystrom wrote:

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.
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Bob wrote:

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
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Brian Nystrom wrote:

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.
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