Brake lights and turn signals don't work (but head and tail lights do) on 1998 Ford Expedition

Question

A friend of ours just bought a 1998 Ford Expedition.

Not working:

• Hazard flashers
• Turn signals
• Brake lights

However, head and tail lights both work when they're turned on.

We tested the brake light switch, there's continuity when the brake is pressed. The plug that plugs into the switch has ~12v current. However, in the fuse box neither the 15A or 5A fuses that are supposed to deal with brake lights/turn signals are getting any kind of voltage. There is also no voltage at the brake lights (which was expected, given that they just changed the bulbs).

Also looked through the fuse boxes in the engine compartment as well as under the dash, nothing was obviously blown.

The person they bought it from removed the stereo... is it possible that is causing the problem? If not, what are the other possible causes?

Answer 1

On the Expedition the hazard, lower brake lights, and turn signals all route through the multi-function switch.

Gain access to the multi-function switch connector and back probe the light green wire while pressing the brakes.

Does it have power? If it yes back probe the light green/orange and orange/light blue wires while pressing the brakes.

Does it have power? If yes there's a continuity issues between the multi function switch and rear lights. If no it needs a new multi-function switch.