Rinnai RHFE-551FA Service Manual page 63

Troubleshooting
RHFE1001FA/VA
(PS) Pressure switch:
Brown - Ground 13 - 18 VDC n/a 6 - 7
Check from both brown's to ground to ensure circuit is complete.
Room Temperature Thermistor
Yellow - Yellow 10-100 kΩ
Flame Rod
0.8 µA or greater
Rinnai Direct Vent Service Manual 63