As stated I my horn, wiper and power seat control at the same time. I checked all fuses in the 12 gang fuse box in the right console? Is there another fuse box somewhere? Everything else is working fine. Any idea's what the problem could be?
Where is the seat switch? Are all the affected accessories on the switch panel at the helm. That area would be my first guess as to where the issue is. You may have a loose connector or perhaps a broken common wire on the panel breakers
You may have lost the common power on the panel breakers for the horn and wiper. Check for power on each breakers.
Power seats are on the Fues block. Are they switched on the panel too?
Get a voltmeter out and start checking. Frequently the spade connectors loosen up. Give them a gentle squeeze with a pair of pliers and slip back on.