98 hotsprings w/IQ 2000 control center .looking for electronic diagram .History, 230V heater,new circ. pump, heater works if bypass 2nd relay ,relay okay .what tells second relay to open /close?get power to second relay but none out ?? can't get diagram from Watkins manufacturing.
Thanks any info would be appreciated

I have the schematic for an older model, maybe this historical data will offer some clues..

On my older '93 model w/o any solid state circuits, there are two heater relays, the over temp relay is fed by the 240V AC mains, and is controlled by a DC circuit with two over temperature switches and the door interlock switch - all three in series.
The over temp relay feeds power to the heater relay, which is controlled by a DC circuit fed directly from a bridge rectifier. The source of power for the bridge rectifier is the interlock relay which is connected in series with the adjustable water temperature thermostat.

If my spa had that a similar problem, it would be one of three components, the water temperature thermostat, the bridge rectifier or the relay.