cluster connector

First, please post your year make and model

Next, what do you have for a service manual

The orange wire is all dimmer controlled dash lamps. The fuse is the small end fuse marked "inst."

THIS IS A bit of a TRICK

The orange wire, and the inst fuse, will ONLY HAVE POWER

When the tail light circuit is good and working and has a good fuse

When the headlight switch is either park or head

When the dash dimmer is twisted "somewhat left"

Only then will the inst fuse "get power" on both ends.

The other wire you mentioned is your "ignition run" wire and supplies power to the cluster with the key in "run."

Might be several reasons why things don't work

Ground issues. Best to add a ground to the cluster PC board run it out and bolt it to the column support

Loose PC board pins. They must be soldered and otherwise repaired

If this is NOT a Ralley dash, the instrument voltage limiter "socket" (spring contacts) may not be making contact with the board traces

The IVR itself might be bad

The gauge stud nuts might be loose / corroded

Lamps........The lamps might be bad, loose, corroded in the sockets. The socket fingers might be loose / corroded as might be the PC board itself.