OJ SCE-120 (ETO 2) Control Troubleshooting Procedure


Customer calls to complain that a snow melt system being controlled by the SCE-120 (ETO 2) is not performing as desired.  Please verify that all software settings and connections are correct.  If everything appears to be OK with the system, follow the procedure outlined below.

OJ had a run of Sensors (SLAB-SS) that may exhibit a failed temperature sensor section of the SLAB-SS.  

A Tech Support Rep will forward the test procedures for these sensors to the customer. These test procedures are attached to this bulletin. Doing these tests can get us the answer as to what is causing the issue with the systems. These units may fall into a range of sensors manufactured by OJ Electronics that had a bad temperature sensing circuit in the slab sensor, or they may not. There is a chance that these sensors may have been damaged by hot asphalt as a result of incorrect installation procedures not in compliance with our Installation Instructions. The testing procedures will give us an indication of what is really the issue with the system. 

If there are NO proper readings at all from the sensor, the unit has probably failed because of improper installation (hot asphalt damage to the sensor or the sensor cable).  This situation fwill not be covered by WarmlyYours or OJ.

If we find the SLAB-SS sensor is part of the suspect manufacturing run with the bad temperature sensing circuit, we will forward the results to the OJ and we can provide the customer with either replacement slab sensor or an ambient air sensor for the OJ-prescribed work-around at no charge, whichever one the customers prefer. Please see the attached troubleshooting guides describing the tests and work around procedures. 

If the sensor readings indicate a manufacturing defect as described by OJ, please forward results to Technical Support Supervisor or Manager.




The voltage for the sensor heating, supplied by the ETO2 is 28 Volt DC.  Until August 2010 the same voltage was 24 Volt.

With “Sensorheat” set to “AUTO” and “Moist crtl” set to “ON”: The supply for the sensor heating will only be present if the measured temperature is below the setpoint temperature – but not when the relays are closed.

Screw Information (form OJ) to hold the sensor in the housing:

The screw is a 5x40 mm stainless steel screw with countersunk head.

It is included in the package at ETOK-1

Written by Scott Rosenbaum
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