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UBXC-UDXC-IOM (01-24) 1042980-0
Unit Troubleshooting Using DSI Control Module
NOTES:
• If troubleshooting indicates that repair of the DSI control module is required, note that its only
replaceable part is the fuse (see Figure 18), which is a type ATC or ATO 3A fuse, color code
violet (PN 201685).
• IMPORTANT: When using a multimeter to troubleshoot the 24V circuit, place the multimeter’s test
leads into the connectors located on the ignition control. Do not remove connectors or terminals
from the electrical components. Doing so can result in misinterpreted readings caused by the
control module’s fault mode monitoring circuits.
• Remove and reapply power to the control module to view the last five fault codes stored in its
memory. The most recent to least recent fault codes will be displayed.
The SSD on the DSI control module (refer to Circuit Board (DSI Control Module) section) may be used to troubleshoot
the unit. The control module monitors the operation of the heater, and the display indicates normal operation and
various abnormal conditions. If the heater fails to operate properly, check this display (refer to Table 26) to determine
the cause and/or to eliminate certain causes. Remove and reapply power to the control module to view the last five
fault codes stored in its memory—the most recent to least recent fault codes will be displayed. See Figure 27 for a
flowchart for troubleshooting the unit using the DSI control module.
Table 26. Circuit Board (DSI Control Module) Display Codes
Display Code Status Display Code Indication
Steady
— Normal operation—no call for heat
0 Ignition sequence active
H Normal operation—call for heat (strong flame)
Flashing
2 Normal operation—call for heat (weak flame)
L Lockout from failed ignition or flame loss
3 Pressure switch is not closed within 30 seconds of venter motor energizing
4 Pressure switch is closed before venter motor is energized
5 Limit switch or rollout open
6 Undesired flame
7 Polarity reversed
Steady Off Internal fault/power failure
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