2009 honda accord ex-l. tail brake lights don't go on when I step on brake pedal but 3rd light works. have tested the following - cruise control works. horn works. bulbs flash when I press on key fob to lock doors. flasher and back up lights work. no warning lights on control panel. any ideas?

 

1. Have you checked that the bulbs are actually okay? They are dual filament bulbs. One filament for the taillight and one for the brake light.

2. If you have a voltmeter, you can test if there is power on the Lt Grn wires with the brake pedal depressed.

3. Both brake lights share a common ground. The ground is G602, located on the left side of the trunk area. You'll have to remove the plastic trim panel.