Southern California Edison is upgrading facilities in Chino Hills in the vicinity of Soquel Canyon Parkway.
Nighttime work, between the hours of 8 p.m. to 6 a.m., began Friday, Aug. 9 and will continue to Saturday morning Aug. 17.
During the upgrade, traffic signals on Soquel Canyon Parkway at Pomona Rincon Road, Butterfield Ranch Road, Slate Drive and Elinvar Drive may go dark Friday, Aug. 16 between 9 p.m. to 5 a.m. Saturday, Aug. 17.
Motorists are advised to treat a dark traffic signal as a four-way stop.
SCE has placed changeable message boards on the roadway to notify motorists.