I ordered a new capacitor. It is a 161-193 uf 110VAC, so I think you are correct and it's only used on the LO side. Makes me a little skeptical that this will resolve the problem, but much less than the $450 for a new motor. I don't think it could be a configuration thing, unless someone snuck into my backyard and started messing with the controller, but I will check.
The relay has two top terminals that Omron labels as 0 and 1 where the two small 24 VDC (volts DC) coil wires connect. When the board sends 24 volts DC to the relay coil, it powers an electromagnet and closes the contacts.
There are 4 terminals along the bottom that Omron labels as 2, 4, 6 and 8. See the Omron picture below.
When the coil closes the relay contacts, terminal 2 connects to terminal 4 and terminal 6 closes to terminal 8.
I was calling the bottom row terminals 1,2,3,4 from left to right. Using this description, terminals 1 and 3 get the line power wires. When the coil closes, terminal 1 and 2 connect and terminals 3 and 4 connect.
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You might not be able to see the top coil terminals.
The Aux 2 relay is usually filter low speed.
Using my notation of the bottom four terminals being called 1, 2, 3, 4, terminals 1 and 3 should be powered with 240 all the time and measuring from terminal 2 to 4 should be zero volts when the relay is off.
If you turn off all breakers, and measure the resistance between terminals 1 and 2 and then 3 and 4, there should be no connection. The meter should read O.L, which is open line or over limit.
I received the new start capacitor and installed. I get the same symptoms.
Looking your notes not the relays, I was trying to figure out the leads on the relay on the motor, housed under the cover. I performed the measurements on the two Relays in use (Filter Pump and Aux 2). The terminals (1 & 2) and (3 & 4) where open (meter read OL).
Aux 2 relay is defiantly the low speed on my installation. It matches your picture in the previous post.
With the system energized, I get 120VAC at terminals 1 and 3 on both relays. I get 0VAC on terminals 2 and 4 on both relays. I think this test indicates that relays are not stuck closed. I suppose one could be inoperative and does not close.
I have previously checked the programming and it was setup for 2 speed operation.
This was a working system. I replaced the motor/pump in April of 2019. I have not touched anything electrical since then.