Recently had problems with the trouble code P0179 which was setting off the service electrical system warning indicator.  Found this to be as simple as re-installing the top brake sensor under the dash just above the brake pedal sensor for the rear brake lights! While some may have a bad wire, connector or switch, for me it was as easy as re-installing the switch into the bore and locking it down. 

OBD Trouble code P0179 - TCC/BRAKE SWITCH "B" circuit signal low/short ended up being as simple as the switch itself coming out of the bore! Once re-installed it turned off the "Service Electrical System" warning indicator that was so annoying on the dash.

Hope that helps, perhaps I will get a photo of it tomorrow if possible.