Set Appliance State:
Set Multimeter to DC Volts 
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
CH potentiometer set to minimum
Remove the programmer cover or programmer (if fitted)
Disconnect brown and green plugs from gas valve
CH potentiometer set to minimum
Remove the programmer cover or programmer (if fitted)
Disconnect brown and green plugs from gas valve
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Allow fan to run and ignition sequence to commence.
On the test pins behind plug ST16 measure the voltages
using the long shrouded probes as below:
Test 1: Across pins 12 & 13 (brown wires on connector).
Test 2: Across pins 19 & 20 (green wires on connector) .
Expected voltage greater than 15 Volts DC for both tests.
Notes:
Voltage will only be present for approximately 10 seconds before lockout will occur. This can be reset by pressing and holding the reset button (flashing) for a few seconds.
On the test pins behind plug ST16 measure the voltages
using the long shrouded probes as below:
Test 1: Across pins 12 & 13 (brown wires on connector).
Test 2: Across pins 19 & 20 (green wires on connector) .
Expected voltage greater than 15 Volts DC for both tests.
Notes:
Voltage will only be present for approximately 10 seconds before lockout will occur. This can be reset by pressing and holding the reset button (flashing) for a few seconds.
Isolate as per TOPs P4
and refit as necessary