My '09 GT coupe is running great - no complaints EXCEPT, for the last week I'm hearing a click coming from the rear every 11 seconds. It's a two step click. At 9 seconds there's a faint click followed 2 seconds later by a louder click. Sort of a "tick -(1-2)- TOCK" sound. Speed has nothing to do with the timing of the clicks. It sounds like an electrical relay is cycling but I can't figure out where except that it's somewhere aft of the passenger compartment - maybe on the right side. It's not the gas filler door or the spoiler wing and everything is working as it should. When the car is in park I don't hear it. For a few days after being away I had the "Low Battery Start Engine" message even though it had been on a trickle charger but some driving time and more charger time have remedied that. I mention it because the tick-tock started about the same time. The car has about 21K on the clock and the batteries are at least 4 1/2 years old (when I got the car) so I know they're probably near the end of their life. Before I write a blank check to my indie guy to figure it out I'm hoping to find some ideas here. Thanks!

 

Checked out the batteries today - basically, even though the car starts, they're toast. The clicking is most likely the battery transfer relay. I have two new Interstate batteries going in on Monday, an MTX-49 H8 for the main and an MT-47 H5 for the starter battery. These are the exact batteries that the Bentley dealer here uses.

While changing out the batteries I plan to plug a 12 volt alarm/UPS battery into the 'always-on' power outlet in the trunk to keep power to the various systems and presets so I don't have to set up everything again. Anyone know of any reason not to do that?

 

New batteries went in today and the clicking noise is gone. I did plug a small 12v battery into the power outlet in the trunk during the swap and all settings were maintained. Low battery message is gone too.

 

Bruce, different car, but probably the same symptoms. A couple years back I had a failing battery in a C6 Corvette. It reached a certain threshold voltage (It was below 10.5v) and some of the relays in the engine compartment fuse box began clicking. I had to disconnect the bad battery to get them to stop, and same remedy, a new battery solved that mystery clicking.