What else does fuse #3 do?

While troubleshooting a radio whose display is stuck on, I've been inside the fuse panel on my 1993 Caprice Classic station wagon. This car is equipped with one of the more basic sound systems, specifically the UM6 radio/cassette player. It doesn't have the Bose audio system.

Yet there is a fuse installed in the fuse block at position number 3, which both the car's manual and the (factory!) service manual say is used only for the optional Bose sound system's power amplifier. The schematics in the FSM only show fuse #3 going to the Bose amplifier.

Pulling the fuse out didn't result in anything obvious failing to work. Any thoughts?

does that fuse have power to it, or is it in there as a spare

DROLDS2U wrote:

does that fuse have power to it, or is it in there as a spare

It's got power coming to it, a 10 amp fuse and contact pins in both parts of the fuse socket. Unlike the unused sockets (such as #7), it is not an empty place in the molding.

I did see it marked somewhere as "AIR/LP" (or some such thing--trusting my memory to correctly recall what I saw in a cursory glance is not a good idea) on the printed legend inside the fuse panel cover. This car does not have an air/auto leveling suspension on it. Nor did I observe the air conditioner to stop working when it was pulled out.

According to my 91 OCC manual, fuse 3 goes to the overvoltage relay which is part of the electronic brake control module.