Honeywell 7800 Series Product Data page 19

Table 4. Fault Message and Recommended Troubleshooting (continued) .
Fault Code
Fault 54 Combustion pressure
Comb. Pressure switch fault (Fulton pulse).
Fault 55 Purge fan switch is on when
Purge Fan Sw. On it should be off (Fulton
pulse).
Fault 56 Block intake fault (Fulton
Block Intake pulse).
Fault 57 Purge fan switch is off when
Purge Fan Sw Off it should be on (Fulton
pulse).
Fault 67 L1 and L2 mis-
AC Phase wired/exchanged.
Fault 68 Preignition interlock fault.
Preignition ILK
Fault 105 Relay Module self-test
Internal Fault failure.
Fault 106 Relay Module self-test
Internal Fault failure.
Fault 107 Relay Module flame signal
Internal Fault cross-check failure.
Fault 109 Negative cycle test failed,
Internal Fault earth ground absent or line
voltage phasing improper.
System Failure
1. Check wiring; correct any errors.
2. Inspect the Combustion Pressure Switch to assure that it is
functioning properly.
3. Reset and sequence the 7865. During standby or prepurge,
measure the voltage between terminal 20 and G (ground). 120 Vac
should be present. If not, the combustion pressure switch may be
defective and need replacement.
4. If fault persists, replace the relay module.
1. Check wiring; correct any errors.
2. Inspect the Purge Fan Switch terminal 18 and connections. Assure
that the switch is functioning correctly and is not jumpered or
welded.
3. Reset and sequence the 7865.
4. If the fault persists, replace the relay module.
1. Check wiring; correct any errors.
2. Inspect the block intake switch and assure that it is functioning
properly.
3. Reset and sequence the 7865. During prepurge, measure the
voltage between terminal 7 and G (ground). 120 Vac should be
present. If not, the block intake switch may be defective and need
replacement.
4. If fault persists, replace the relay module.
1. Inspect the Prepurge Fan Switch terminal 18 and connections.
Assure that the switch is functioning properly.
2. Reset and sequence the 7865.
3. If fault persists, replace the relay module.
1. Check L1 and L2 for proper line phasing.
1. Check wiring; correct any errors.
2. Inspect the Preignition Interlock switches and assure that they
function properly.
3. Check fuel valve operation. Valve must close within five seconds.
4. Reset and sequence the 7800. During standby or prepurge,
measure the voltage between terminal 17 and G (ground). 220 -
240 Vac should be present. If not, the preigniton interlock switches
may be defective and need replacement.
5. If the fault persists, replace the relay module.
1. Reset and sequence the 7800.
2. If fault reappears, remove power from the device, reapply power,
reset and sequence the 7800.
3. If fault persists, replace the relay module.
1. Reset and sequence the 7800.
2. If fault reappears, remove power from the device, reapply power,
reset and sequence the 7800.
3. If fault persists, replace the relay module.
1. Reset and sequence the 7800.
2. If fault reappears, remove power from the device, reapply power,
reset and sequence the 7800.
3. If fault persists, replace the relay module.
1. Assure that a good earth ground connection exists at the installation
site and that all earth ground connections are complete and correct.
2. Assure that the 7800 and all loads operate at the same line voltage
phase.
3. Reset and sequence the 7800.
4. If fault persists, replace the relay module.
7800 SERIES S7800B DISPLAY MODULE
Recommended Troubleshooting
19
(continued)
65-0219—1