Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to DC Volts Set meter to measure DC Volts
Gain access to PCB (use Insulation Mat as required)
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Rotate the CH temperature control knob to the OFF position
(This will allow you to see the current system pressure)
Measure the DC voltage between pin 1
and pin 2 on connector X9.
The voltage measured will vary according to the system pressure (refer to the pressure on the display) but should conform approximately to the table below;