210 chassis rearview remote receiver busted

I have a problem with my 1997 E420 that I discovered soon after purchasing it. The central receiver on the rearview mirror for the remote locks/alarm does not work. I have to be very near the drivers door or the trunk to lock/unlock the doors. The red/green lights in the rearview mirror that signal when the doors are locked/unlocked also do not work.

The red/green lights on the driver's door and trunk work fine. Where should I start on this? I have never been great with electrical.

I noticed now that it works in my garage from up to ten feet away. Outside in a parking lot you have to be within two feet of the sensor to make it work. This is with both keys. Battery in the keys?

[KenP]

... change the batteries in the remotes.
It works in your garage because you don't have all that background IR interfering with the weak remote signal. The remote uses an IR LED for the source.... and they aren't very tolerant of weak batteries.
When my batteries start getting weak, I've got to get right up on the sensor.
Pretty surprising to me how fast the batteries run down in these things... I only get about 10 months or so out of a set... of course its dependent on how often you use the remote.
Good news is that the batteries are only a buck a piece from wholesale places and it only takes about 30 seconds to change them.
KenP

Thanks Ken, I'll replace them today....that's if I can find a parking spot with all the last minute shoppers.

[KenP]

Good luck with the shoppers! Its crazy here on the East Coast...
I think if you get them at Radio Shack, etc, they're about 5 bucks each... think your remote will take two...
Merry Christmas!
KenP

Well, I replaced the batteries and there is no improvement in the range. I'm tempted to start taking apart the rear view mirror the see if the receiver "antenna" is hooked up. Any suggestions.