Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
Gain access to PCB (use Insulation Mat as required)
Disconnect connector X4 at the PCB
Disconnect connector X4 at the PCB
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Observation:
If boiler is in lockout reset it then turn mains power OFF then back ON
so that it starts the appliance self check. (AP shown on display).
Measure the voltage from pins 4, 5 and 6 to pin 7 of X4
using the test points on the connector.
Voltages should be approximately as below:
so that it starts the appliance self check. (AP shown on display).
Measure the voltage from pins 4, 5 and 6 to pin 7 of X4
using the test points on the connector.
Voltages should be approximately as below:
| Test | Expected Voltage |
| Pin 4 to Pin 7 | 20V DC |
| Pin 5 to Pin 7 | 22V DC |
| Pin 6 to Pin 7 | 17V DC |
Isolate as per TOPs P4
and refit as necessary