Newell Gurus

Pressure Relief: I know you said to turn the dial to 5 but that would barely be out. I know that 3 times around (open) had let the slide out before so I’m pretty sure that is correct.
Current to HWH bay/computer board - I tested EXTEND (yellow wire) and no current was found. RETRACT (black wire) showed about 10amps if I am reading the tester correctly. So that means I’m not getting current/voltage to the Extend wire.
We did verify that when the Extend button is pushed the slide room 2 pins go UP and when we push the RETRACT button the slide room 2 pins go DOWN.
I made video while we were doing both operations and will check the LED lights.

Ok will trust your judgement on the flow control valve.

You said you had current on the retract solenoid. Was that with the EXTEND button activated or the RETRACT button activated?

THE REAR SLIDE ROOM 2 CAME OUT! (And in and out and in again!)…
I had the pressure relief valve knob set to 3 full turns out from closed and the slide did nothing. I tried the other things and was in the car about to head home and wait for more advice when I thought ‘What would Richard do?’ He would not give up this easily! So I got my wife to go back in and start the coach - this time I screwed the pressure relief knob all the way IN and then out to about 5 on the dial (which is barely out). Wife clicked the EXTEND button and VOILA!!! The room slid out! Then we tried it a few more times including shutting everything down, including the engine and doing the process all over again in/out. It seems to be working perfectly!
Now here is the odd part: Before I turned the knob to 5 I tested the current and the RETRACT button when activated showed current and the EXTEND button activated did not show any current that I could tell. I got excited and forgot to check the current with the knob set on 5 rather than 3 full turns - I will test that when I go back to the storage building.
THANK YOU RICHARD for all your patience and helpful advice - you are a great asset to this forum and a tribute to Engineers everywhere :-)
Thank you to all the others that chimed in to help also!

Fantastic !