Hi all,

I cannot find a thread with my conditions so I thought I would start a new one. I recently tried to get my 2009 C6 out of winter hibernation only to get the honking alarm when I attached the battery (never happened before). None of the buttons on the fob would stop it. After that stopped on its own, I tried to start the car but I was getting the "No Fobs detected" message. The car still made all the same clicking noises as usual. I checked the batteries in my key fobs and they are good. I was able to put a key fob in the glove box slot and start the car.

After a bit of research, I came across posts that said the RCDLR commonly fails, likely due to cold solder joints or blown relays. I took mine out of the car. The connectors and wires all look fine. I re-flowed the solder on all pins from the two connectors used (both sides of the board) and a few others that looked dull or lean. I uses a magnifying glass to ensure they all were done fully and there were no solder bridges/shorts. I also tested and measured all four relays. They are all good, and as I mentioned it makes the same clicking noises it always did.

I plugged it back in and no change. I then found the long auto-learning procedure so I did that. This is the process, in case I got it wrong.
- Turned the physical key in the trunk lock 5 times within 5 seconds.
- Got the "Off/Acc to learn" message
- Pressed the bottom half of the start button and watched it count down from 10 minutes.
- Repeated the same thing two more times.
- Got "Ready for Fob #1" so I put the first fob in the glove box slot.
- After a few seconds, got "Ready for Fob #2". I took out the first fob and put my second fob in the slot.
- After a few seconds, got "Ready for Fob #3". Pressed the bottom half of the start button. The message disappeared and went blank.

I then tried to start the car and still got "No Fobs detected" after the clicking. I tried the acc or on states as well with no change, so I just unplugged the RCDLR and disconnected the car's battery. I realize now that I didn't try pressing any of the buttons on either key fob. I wish I had tried that before disconnecting power again.

Does it still sound like my RCDLR is bad, or could it be something else?

Thanks for your time.

 

The procedure does say to press the buttons on the fob to complete the process so I’d program them again. If that doesn’t fix things, best guess is that there is and was nothing wrong with the fob or RCDLR. The fob batteries are another story. Just because they seemed to test good doesn’t mean they are. Get a new Panasonic or Eveready lithium ion battery from some store that sells a lot of them so you’re not getting one that’s sat on the shelf and expired. To make sure, check the expiration date on the packaging. A new coin battery should read 3.3v. When you put it in the fob, check that the contacts are clean, not corroded, and grip tight. And make sure the battery is the right way up.

 

I didn’t think my answer above though. The fob needs power in order to complete its programming if a final key press is required. So replace the batteries in both fobs as I described above. Then see if they work. If not, then you can try reprogramming them, including pressing the required buttons at the end for each fob.

 

Wow, you must either be psychic or a genius (or both)! The fob batteries test 3.2V open, but I found a 120 Ohm resistor and put that across them. They dropped under 0.9V under load. I found new ones in a package and tried it again. Car worked right away. Thanks so much! Glad I didn't wreck my RCDLR messing with it. Now hopefully I can get everything back together again without breaking anything (or dropping a screw down the back ...).

 

I too suspected my RCDLR was failing.
Through a lot of support here on the forum, as well as a friend who is very knowledgeable when it comes to electronics in general, we found it was nothing more than a communication failure between the RCDLR and the TPMS sensors.
I was close to pulling out the RCDLR but didn't have to as issues cleared up once we were able to program my new TPMS sensors.

 

Well, I’m neither, but I do remember what I read. You’re not the first to be tricked by a coin battery which has good enough voltage but is close to being discharged. Good catch by testing it under load to prove it. You’d also be surprised by the number of owners who reprogram their fobs needlessly thinking it will fix a “no fob found” problem. The car doesn’t forget what fobs are programmed to it, unless deliberate steps are taken to erase it from memory. There’s only one way I know of in which the fob can get out of sync with the security system incorporated in the RCDLR, and you’d have to work at it to make that happen. Then it would need to be reprogrammed.

 

There's no replacement for experience! Thanks again! I'll get everything put back together tonight and confirm it all works.