73 Horn issue and dash removal question

My car is a 73 XR7 convertible. Trying to straighten out some wiring issues on my car. The horns are not working. At this point it appears to me that I am not getting power to the fuse panel. I have probed both sides of the fuse location with a test light and am getting nothing, the fuse appears to be ok. The cigarette lighter doesn’t work either and I believe it is the same fuse. The horns will sound if I apply power to them directly. The turn signal switch is new and also have a new reproduction rim bow steering wheel so I don’t think the problem is at the steering column. Where do I go from here?

2nd question, is what is involved in removing the plastic dash frame on this car? Due to some previous vertigo issues I am not real good at laying on my back under the dash. I do have the instrument cluster out currently and cannot see the under dash wiring to my satisfaction.

Appreciate any suggestions and apologies if this has been covered before on the forum. Thanks

Fuse should be the bottom left, with the majority of the underdash harness at the top. Yes, horn and cigarette lighter are on same fuse. Courtesy lights are on the bottom right fuse. If those don’t work, I suspect main line to BAT power (centered clips) is busted (common on these fuse boxes).

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Check fuse with a continuity tester or meter. The filament may be broken inside the end caps where you can’t see.

Just a suggestion, try plugging in 1 horn at a time, when I got my 73 having both plugged in made them inoperable.
Working under these dash’s is truly a pita…some people remove the drivers seat for better access.
X2 as mentioned pull the fuse and test. Just saying, last time I curled up like a pretzel testing with a probe I kept hitting the hot side (unknowingly)and drove myself in circles.
You have the IP out, so are you talking about removing the “plastic dash frame” that covers the IP and rest of the dash? If so the dash pad has to come out, then they are all Phillips screws for the plastic cover. One piece just look in all the holes.

Removing the dash is not easy, but doable on a weekend. First, unscrew the pad and top plate. Next, remove the trim piece below the column, and then unbolt the steering column and just let it founder. Remove the steering wheel (you’ll be glad you did). If you’re intention is to remove the dash as a whole, unplug the main wiring harness at the green disconnect under the dash. Remove the trim plate holding the radio, and heater controls, and unplug the radio and heater control lines. Just to the right under the dash is a brace holding the dash to the firewall, remove the one bolt securing it. While you’re under there, remove the four bolts holding the dash to the right and left sides at each doorway. Now, remove the “A” pillar trim pieces, being careful not to crack or break them. At this point remove the two bolts that are now exposed on the top of the dash. That will be a little tricky, as you are very close to the windshield glass. Use an offset box end wrench for that. By now, you should be ready to remove the entire dash. GET A FRIEND YOU TRUST TO HELP YOU WITH THIS!!! In the course of doing this, you may run across something I missed telling you about, but before starting this job, look everywhere with a strong light as you are taking this apart. Oh, and by the way, chock your wheels, as you will need to put the shifter back in the 1 position because it will be in your way. Hope this helps. Maybe some of the other “keyboard commandos” can add to this.