SERVICE HANDBOOK

ULTRA HIGH EFFICIENCY POWER VENT/POWER DIRECT VENT - SERVICE MANUALFAULT MESSAGES (CONT)DISPLAYED MESSAGECONDITION/INDICATES“Gas Valve Failure”The control system has not detected any currentthrough the gas valve after it has been energized.“Communication Failure”Loss of communication between the CCB and theUIM.CHECK/REPAIR• Turn off power - check all wiring and connectorsbetween the CCB’s J6 Socket (page 35) pins 2& 15 and the Gas Valve’s solenoid coil. Repair/replace anything worn or damaged as necessary.• Perform close visual inspection of the pinsinside the CCB J6 plug and socket - ensureplugs and sockets are mating properly and providinggood contact. Repair/replace anythingworn or damaged as necessary.• Turn off power - disconnect the Gas Valve wiringplug on top of the Gas Valve solenoid coil.Check Gas Valve solenoid coil resistance withan ohm meter at the solenoid coil terminals.Normal resistance is approximately 7 millionohms. If the Gas Valve solenoid coil is an opencircuit - replace the Gas Valve.• Check for 24 VAC at CCB’s J6 Socket pins 2 &15 during the Ignition Activation operating state(the Gas Valve status icon will be visible on theUIM display during this period.• Call the technical support phone number shownon the water heater labeling for further assistanceif the problem has not been correctedafter performing the procedures outlined here.• Turn off power - check the communication cableconnections between the J2 Socket on the UIMcircuit board (page 27) and the CCB J16 Port(page 35).• Try a new communication cable (standard categoryV network cable) between the CCB and theUIM.• Call the technical support phone number shownon the water heater labeling for further assistanceif the problem has not been correctedafter performing the procedures outlined here.Technical Literature Department 52 of 52 Ashland City, TN © 2008Servicing should only be performed by a Qualified Service Agent