I got a new truck bed and decided it was time to finally fix my rear lights. Both blinkers work but only one brake light. It has really got me stumped. Also the rear running lights don’t work and never have. When using a multi meter I get continuity between the running light positive and the common negative but only when the rear light harness is plugged in which means the short is somewhere on the way back or under the dash? Any tips would be appreciated about tracking this stuff down.