Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to DC Volts Set meter to measure DC Volts
Refit connector X2 to the PCB
Remove connector from pressure sensor and make safe
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Test 1:
Measure the DC voltage between the small soldered point marked "5V" just to the bottom left of connector X20 and a suitable earth.
Expect approximately 5 vdc.
Test 2:
Measure the DC voltage between terminals 8 and 9 on the incoming mains terminal strip.
Expect approximately 22 vdc.