Auto-Drain Valves on waste tanks

Hi
The auto-drain valves for the waste tanks on my 2002 29ft Cruiser are not working
There is no light displayed when the switches are operated. Are there fuses or breakers in the circuit which could possibly be the problem and where are they located? Unfortunately living in the UK there are very few dealers who are able to assist including the company that imported the RV into the country for me!
Thanks in anticipation
Chris

me again
Oops the Cruiser is a 2007 model, the 2002 is my Grand Vitara toad. A 'senior moment'
Chris

I had the same problem on my 2006 PC.  For about 12 dollars each, I replaced the electric valves with manual valves. Took less thanb an hour to make the change and they really are not that much harder to reach and open... Plus, we sometimes use our unit in winter and electric valves seem to be 'iffy' at best during cold weather.
Alan Jarand