Check the relay first. I would then check power at the pump itself. Just use 12v and put the wires to the plug and see if the pump runs.....if not, then you may have a clogged pump. Sometimes the dessicant breaks down and will clog the pump. Will have to pull the pump to clean it up.
If all else fails...the pump is shot and I don't know if it can be rebuilt. I found one on ebay to replace my non-working pump.