Thermo King SR-2 SmartReefer2, Diagnostic Manual

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Section 5 – SR-2 Diagnostics
52 CHECK HEAT CIRCUIT
Page 1 of 2
Alarm Type Check or Shutdown Alarm (Pretrip Only)
Associated Alarm
Codes None
Component Description and Location
The pilot solenoid is located in the condenser section adjacent to the receiver tank.
Circuit Description
The pilot solenoid circuit is a two wire circuit. The 26-01 wire connects the interface board connector J7 pin 3 to
one side of the pilot solenoid. The CHPS wire connects the other side of the solenoid to chassis ground at the
ground plate near the unit battery. The solenoid is not polarity sensitive. The switch wires are routed in the Main
Harness. An Smart FET on the interface board supplies power to the 26-01 circuit.
How Alarm is Set
1. This alarm is set if the measured shunt current is incorrect during non running Pretrip Test. Current is
measured with the output on and off.
2. The alarm is set as a Check alarm if the current is not within specifications when the solenoid is energized.
3. The alarm is set as a Shutdown alarm if the current does not return to 0 when the device is de-energized.
How Alarm is Cleared
This alarm is cleared manually.
Diagnostic Procedure
1. Check the operation of the pilot solenoid circuit using Interface Board Test Mode. Be sure the heat LED 8
lights.
2. Use the HMI control panel amps gauge to check the current drawn by the pilot solenoid, while operating the
high speed solenoid with Interface Board Test Mode. The current draw should be approximately 0.5 amps.
3. Energize the pilot solenoid using Interface Board Test Mode and check for battery voltage on the 26-01
circuit. If voltage is present at the pilot solenoid, and no current was measured in the step above, replace
the pilot solenoid coil.
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02 February 2005