Tri-Stepper CAN Fail
system
Description
1-1MSM cannot communicate with 1-2MSM over the CAN bus, and the unit shuts down and alarms.
Activation Conditions
1-1MSM cannot communicate with 1-2MSM over the CAN bus.
Unit Behavior
Engine and Electric Operation: Shut down and alarm. The stepper valve module status LED may be on steady green (not pulsing) or red.
Reset Conditions
Auto reset when CAN communication is restored, alarm reset or alarm may be manually reset by turning the unit off, then back on again.
Corrective Actions
1. Check both active and inactive alarms for other “NO COMM” alarms. a. If more than one alarm, record all and proceed to step 3. b. If this is the only “NO COMM” alarm, replace module. 2. Check CAN Bus a. Inspect connector pins and terminals on 1-1MSM and 1-2MSM. No damaged or corrosion in connections. b. Check for CAN circuits: • CAN Hi: 1-1MSM-12 and 2, 1-2MSM-29 • CAN Lo: 1-1MSM-3 and 6, 1-2MSM-30 • LGC Power (+ 12 VDC): 1-1MSM-10 • LGC GND: 1-1MSM-1. 3. Check system - Clear active and inactive alarms. Start unit and monitor for additional “NO COMM” alarms.