Marquis - 2000 Recreation Series - Troubleshooting Spa Low Speed Failure

[Catrock]

220v.

2-Speed motor.

Problem:
Low speed/circulation mode - doesn't turn on.  When spa circuit breaker is turned on - I hear relay click.  Top-side control panel displays 00 - then displays the spa water temperature.  The Spa heater does not turn on.
Pressing the spa jet top side turns the jets on high speed-2.  The spa heater turns on - and does heat the water.
This problem started a few weeks ago.  The 20A SC fuse would blow.  Checked the heater with a multimeter.  It was faulty. The spa heater was replaced.

The low speed still doesn't operate.
The pump was replaced in 2011. It is an UltraJet -
PUUPC2202582F 56Fr 8.0-8.8A 230V 2-spd 2" SD/CS Ultima Plus.

I am not sure what to do next to determine if the pump is faulty or if the controller PCB could be faulty.

Any help in areas to troubleshoot next is greatly appreciated.

[Catrock]

Greetings.   I have now replaced the pump.  The problem still persists - the low speed does not engage.  The PCB board is a Balboa 52149 (Marquis Circuit Board 600-6273). 
Is there a way to test to board or relay(s) before replacing it or at this point is it a certain failure point?

Thank you

[cranbiz]

Do you have a multimeter and if so, do you know how to use it?

When low speed is selected, check the output of the relay. You should have voltage. If not, bad relay or bad trace on the board. You might want to pull the board to inspect the back side.

Being as you have replaced the pump, I'm leaning to the low speed relay. Relays can be replaced by someone with soldering experience and are not overly expensive.

[Catrock]

@cranbiz  Thank you.   I will check out the relay power and inspect the board.

[cranbiz]

@cranbiz  Thank you.   I will check out the relay power and inspect the board.

Also try swapping the high speed and low speed connections. If the problem moves, you know it's in the low speed power circuit and most likely the relay or traces.

[Catrock]

@cranbiz - I swapped the high speed and low speed connections. Once I flipped the breaker on - the relay flickered (non-technical term but that's what it seemed to do)  Then the high speed and low speed were both operational.  I turned off the breaker and put the low and high power connections back to their original relay connectors.  Powered the breaker on. 
Whatever happened the motor now operates properly low and high speeds and circulates the water while heating to temp (102) then the motor stops as it should under normal operations.
Sounds like the low speed relay had - for lack of technical term - stuck.  Swapping the power leads flushed out the stuck..
The spa has been running normal now for over a day. 
If the problem happens again I will know it's the relay or traces.
Thanks for your help.

[Catrock]

~Well.  My spa ran for a few days.  The motor seemed to run too long - even when the heater was disengaged.   I pulled the PCB.  No signed of a burnt backing or traces  Probably going to replace the PCB.

[cranbiz]

I would go ahead and find an electronics guy and replace the relays. Should be far cheaper than buying a new board.