[Toadie]

Sooooo, apparently I missed labeling these two wires and can’t figure out what they go with. This area is on the passenger side behind the glove box. There are two mystery wires: one with a brown harness and the other a black thin harness.
Turn signals work…can’t figure it out.

Also, where does the glove box light connect?

 

[Airfido]

Maybe the brake light relay for one of them? Our ‘71 has the relay located right behind the glove box. Not sure about the light.

 

[Klutch]

Those look like factory radio connectors, but being on the passenger side would suggest otherwise. Are you sure they are located where they are supposed to be?

 

[HoustonGlock]

IIRC, there should be a buzzer module that plugs in there for seat belts, to make an audible noise unless belt is buckled with occupant in the seat.

Most were removed as no body wanted that noise.

 

[Hemikiller]

This should help you out.

The glove box light switch plugs into the convenience group harness. If you don't have the option from the factory, the connectors may not be there.

Link to wiring diagrams - 1971-1973 Mustang Wikipedia – Everything about the 1971, 1972 & 1973 Ford Mustang

 

[Toadie]

Maybe the brake light relay for one of them? Our ‘71 has the relay located right behind the glove box. Not sure about the light.

Yeah the brown one does appear that way per the diagram that Ken sent me. Can’t figure out where it goes though unless I’m missing an entire relay. SMH.