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.