Toyota Repair: 99 Camry lower brake lites failure, bulb failure, mr ted

Question
Mr. Ted, sir.  I replaced r.r. tailight bulb to correct a rapidly flashing turn signal.  Two days later the rear light warning on the dash illuminates and stays on as soon as brake pedal is pushed.  The only brake light working is the upper brake light on the package shelf"".  I've tried switching bulbs from side to side.  I've opened up the trunk lid compartment and tested those bulbs on 12V and they light.  I will be rechecking all wiring, connectors, and grounds today.  The generic schematic I have indicates that possibly the rear bulb failure sensor might be checked as well.  I read also in earlier posts the wire bundle that runs along the left rear trunk hinge is prone to failure.  Any suggestions from your experience and expertise on these vehicles is much appreciated.  The key here seems to be that (1) the upper brake light works and (2) that other tailights (backup, turn, running) work.  Thank you very much.

Answer
The first thing I recommend is that you replace all the bulbs with new ones, regardless of whether they look or test good.
If after that there is still the same problem make sure that all the ground connections next to the bulb sockets are tight, if that doesn't resove the problem there may be a problem with the wire harness or the tail light failure relay in the trunk.