My detailed info doesn't go back that far, but I believe it likely that your coach has a brake controller connector under or inside the dash. The hard part is finding it.
Look under or inside the dash for a 3 x 2 (six pin) connector, with blue, red, green, white and brown wires. In some cases, you'll find the pigtail instead, which has tags on each of the wires. Follow the pigtail into the dash and you'll get to the connector.
It's very likely that the aft end of the brake controller wire is not connected to your hitch connector, for a coach as old as yours. You can find it, though, and extend the wire to the connector.
2008 Holiday Rambler Admiral 30PDD (Ford F-53 chassis)
2009 Honda Fit Sport