TM 5-3810-307-24-1-2
Table J-2. Fault Codes (Continued)
Fault Code
Fault Description
Cause/Corrective Action
050
Too many no start attempts
The coolant heater control unit is interlocked after it
has switched on ten times in succession (i.e., twenty
failed starts) without flame detection (fault code 052).
Check the fuel supply, glow pin, exhaust piping,
combustion air piping, and flame sensor. Cancel the
control unit interlock and clear error memory by
pressing both "L" buttons simultaneously.
051
Faulty flame recognition
Flame sensor signals a temperature greater than 176
F (80 C) after four minutes of cooling air. Impedance
at flame sensor is > 1300 ohms. If no combustion,
using multimeter set for ohms, check the flame
sensor. Flame sensor values: 900 ohms at -13 F (-
25 C), 1100 ohms at 77F (25 C).
052
No start safety time exceeded
No flame was detected during startup phase. Flame
sensor value less that 194F (90 C) 1350 ohms.
Check the fuel supply, glow pin, exhaust piping,
combustion air piping, and flame sensor. Flame
sensor values: 900 ohms at -13 F (-25 C), 1100
ohms at 77F (25 C).
053
Flame cutout in boost mode
Coolant heater has started (flame detected) and
indicates flame loss in a given power setting. Check
054
Flame cutout in high mode
fuel flow rate, combustion air blower speed, fuel
supply, and exhaust/combustion air piping.
If
055
Flame cutout in medium
combustion OK, check flame sensor. Flame sensor
mode
values: 900 ohms at -13 F (-25 C), 1100 ohms at
77F (25 C).
056
Flame cutout in low mode
059
Water temperature rises too
Check coolant circulation (012) and temperature
quickly
sensor (060/061).
Control sensor signals a temperature value outside of
060
Temperature control sensor
the measurement range. Check the connecting wiring
interruption
to temperature sensor (0.35 yellow) as follows:
061
Short circuit temperature
Remove the control unit and disconnect the internal
control
connector B5.
Using multimeter set for ohms,
measure impedance between pins 9 and 11 (yellow
wires) of B5: greater than 10K ohms (fault code 060)
and less than 100 ohms (fault code 061).
Temperature sensor values: 650 ohms at -13 F (-25
C), 1000 ohms at 77F (25 C).
Change-1 J-41
