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If the resistance of the Temperature Sensor is below 390 ohms the Control System will lock out and display
Temp Probe Short on the UIM. If the resistance of the temperature sensor is above 56,000 ohms the Control
System will lock out and display Temp Probe Open on the UIM. The electrical circuit breaker that serves the
water heater must be turned off and on again to reset the Control System. Note; the Control System will not
reset unless the condition has been corrected.
TEMPERATURE SENSOR TEST
1. Turn off the circuit breaker that serves the water heater.
2. Remove the top cover on the water heater.
3. Disconnect the four pin plug/socket connection from the Temperature Probe outside the CCB enclosure
in the middle, see Figures on next page.
4. Using an ohm meter: set the ohm meter range to a scale just above 30,000 ohms.
5. Check resistance between the two inside pins (black wires/Pins 1 & 4) of the plug end from the
Temperatures Probe, see Figures on next page. Compare the measured resistance to the values given
in "Temperatures" Table below. Temperature Probes are very reliable and should only be replaced when:
• The resistance is above 56,000 ohms (open) or below 390 ohms (shorted).
• The nature of the service problem is temperature control and the resistance readings are considerably
(± 25%) different than the values in Temperatures Table below at the given temperature.
CELSIUS
4°
21°
38°
49°
55°
60°
71°
82°
ECO CONTINUITY TEST
1. Turn off the circuit breaker that serves the water heater.
2. Remove the top cover on the water heater.
3. Disconnect the four pin plug from the Upper Temperature Probe, see Figure on Page 30.
4. Ensure tank temperature is less than 100°F (38°C) - dump water to lower tank temperature if necessary.
5. Using an ohm meter set the range for continuity testing.
6. Check continuity between the two outside pins (red wires/Pins 2 & 3) of the plug end from the Temperature
Probe, see Figure on Page 30 pin layout.
TEMPERATURES
WATER TEMPERATURE
FAHRENHEIT
40°
70°
100°
120°
130°
140°
160°
180°
Servicing should only be performed by a Qualified Service Technician
TEMPERATURE SENSOR
RESISTANCE IN OHMS
26,435
11,974
5,862
3,780
3,066
2,503
1,698
1,177
29
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