2007 cadillac dts passenger side rear brake light is not working

Has it got power

I would try measuring for 12 volts at the socket while the turn signal is on.

faulty earth wire on the wiring cluster for the heat light check with a meter and fix the earthing point.

Fast flashing dash signals mean there is a bulb issue-DEFINATELY!

Your right rear turn signal bulb is blown.Replace the bulb and the fast blinking will stop.

Hello! The Right Stop/Turn Signal are the same bulb...The most obvious answer is to replace the bulb...But if you have done that without success let me know and I'll find the fault....Guru....saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

I have a 2007 Chevy Express with the same problem. Just happened. Brake and turn signal not working on left side. Fuses good, bulbs good (dual element lamp, turn signal and break are same element) running lights work (other element) Relay blinks fast and not getting voltage at light for blinker or brake. Is there something else in the circuit I need to check. Took it to an ASE mechanic and he couldn't or didn't want to fix it. THANKS Let you know if I fix it tomorrow.

Change the bulb on the passenger rear.

You have a bad connection at the rear passenger side turn signal. It is either the connection is corroded or a wire is loose on the ground side of the circuit.

Usually that fast blink is a good warning that one of the signals is out. Double checked that bulb is same # and all that ? What number is on the bulb? if it's 2057 or 3057, try pulling wires on side of bulb with fingernail, outward to make better contact, to see if that helps.