I have an AQUALINK RS 4 with the optional Spa Side Switch, for a pool and spa. The light in the spa came on by itself without the pump running or attempting to turn it on. It came on and off intermittently. I was able to turn the spa light on from the inside control as well as the side switch with no problem. All other functions work as well from the side switch and the inside control. To keep the spa light from coming on I popped a gfi switch on an outlet that keeps it from coming on. I noticed that the red light in the middle of the spa side switch is constantly onů barely illuminated, which is not supposed to be, unless of course you have one of the elements turned on, such as the light. This started during an evening of heavy rain. The unit has been in place for 10 plus years with no problems.
Any suggestions to trouble shoot would be much appreciated.