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Customer Concern: Lower brake lamps are inoperative. Center High Mount Stop Lamp (CHMSL) functions correctly. Rear turn signals function normally. New brake switch tried. No voltage to the Yellow/Black wire with the brakes applied. Tried another CHMSL relay in the Underhood Bussed Electrical Center (UBEC), fixed.
Tests/Procedures: 1. Test for 12v from the brake switch on the White wire.
2. Test for 12v at column connector, Yellow/Black wire, pin A10 at C211.
3. If OK, replace the turn signal switch.
4. If not OK, test operation of the CHMSL relay in the UBEC.
Potential Causes: Center High Mounted Stop Lamp (CHMSL) Relay
Turn Signal Switch