Purpose and Applicable Part/Model Numbers


This document addresses issues with LEDs lighting up and premature alarms.


Troubleshooting Steps 

Reported issue: No lights on the DCX panel

Possible Causes

1. The two GMT fuses on the board are blown

2. The return cable is not wired to the bottom pin of the green terminal block

3. The jumper at the bottom right hand corner of the board is not set properly

4. The return cable is not wired to the battery stack correctly. It should be wired to the opposite end of the battery string as the termination plate.


1. Visually ensure the return cable is terminated to the bottom (pin 5) of the green terminal block, see below diagram

2. Test the voltage between TP1 and the return line. It should read -54V. TP1 is located near the bottom of the board under the right hand corner of the EPO enable/disable switch.

Fig 1: Point 1 is the voltage selection jumper. Point 2 its Test point 1 (TP1).

DCX issues cont.

TRD Problems

Premature Alarms

TRD units are tested with the temperature sensors they are sent with. If the TRD is replaced but the temperature sensors are not replaced there may be a calibration issue. A short of one of the legs on the temp sensors to the lug can cause the issue. A failed temp sensor can also be an issue. 

Temperature sensor with shorted legs: 

If you are experiencing problems, please contact Comm/net Systems Support


Comm/net Systems Inc. Support


(206) 282-8670

or submit a support ticket through this portal.