Billw5300, sorry I did not pick-up on your post sooner. On the older Alpines, as you discovered, the solenoid is located behind the front upper cabinets. Found this out when I removed the above the drive seat TV cabinet and gutted the two to the right. This gave me access to fix the Marker lights, rework some old wiring and rebuild the insides for better storage. At the same time will build an easy access panel for future needs -- such as replacing the horn solenoid.
Tim & Ruth
Alpine Coach 1999 40FDS, 350 ISC