What is not shown on the ford diagram is a red wire on the switch which goes to the blacked out pin on the switch side of the diagram steering column wiring. A 1968 mustang turn signal switch has 10 wires not 12 there is no brn or yel blk as on that drake switch. Troubleshooting sequential turn signals this guide covers troubleshooting 1969 1973 mercury cougar 1969 1971 thunderbird and 1969 1970 shelby mustang sequential turn signals.