Brake + Turn Signals = Not Working

[litew8]

Anyone got some insight on this type of trouble?

Rear:
Tail lights = Yes
Marker lights = Yes
Brake lights = No
Turn signal = No

Front of cab is working ok.
No power to two of the three wires at the rear connector. Does this sound like a bad brake switch or turn signal switch? Not sure if the rear turn signals go through the brake switch or not. Any help greatly appreciated. We don't think it is a ground issue since there doesn't seem to be power at the plug for two.