Ihave a 86 mustang lx and my tail lights will not work my fuses are good i put new bulbs in the tail lights and marker lights.my blinkers work but my insterment lights don't around the speedomiter & r.p.m. guage. could it be in the main light switch.

 

could be the switch or then agian wiring problems can be a bitch to chase down.

 

make sure all the connector piece jawns are connected under the dash, someone on here mentioned that one of them controls the brake lights. try that.