Solenoid and relay-- same thing.
NO, the solenoid(relay) does NOT ground thru its mount
You have 4 connections on the relay. Large Battery positive posts and 2 small posts. 1 large post goes to the battery pos. 2nd goes to the actual pump motor
BLUE wire is POS when inside panel is turned ON connected to small post
White is the negative to activate the solenoid(relay). Copnnedted to the other small post. This comes from the Joystick.
Now, this is why I state to NOT use an Auto part "similar" solenoid. You mentioned, does not the solenoid ground thru its mount? NO. But, most Auto part store solenoids(while not high amp rated for continuous long operation), DO ground thru the mount. AND have 2 large posts and just a single small post activated by a POS 12 volt signal. In this case, IF the solenoid grounded thru its mount, then anytime the BLUE wire had 12 volt power the Solenoid would close and the pump would run. THIS HWH Solenoid(relay) is designed to NOT ground and the completed circuit happens when the White wire small post had a ground(neg). So, does your new solenoid have the 2 small post connections? Did the OLD solenoid have the 2 small post connections? Doug
8600 is white ground
6820 is the blue wire pos
These numbers designate the wires in the HWH schematic
https://www.hwhcorp.com/ml16035.pdf