MSM-1 in Low Sensor Voltage
electrical
Description
MSM sensor voltage is below 4.5V, and the unit gives alarm only.
Activation Conditions
The voltage supply for the sensors on the MSM is below the low voltage limit 4.5V
Unit Behavior
Engine and Electric Operation: Alarm only.
Reset Conditions
Auto reset when voltage is correct, alarm reset or alarm may be manually reset by turning the unit off, then back on again.
Corrective Actions
1. Check System Pressures - Install manifold gauge set and check and compare compressor discharge, evaporator outlet and suction pressures with those shown in Unit Data. Refer to Section 8.8.11 for instruction on comparison. 2. Check Wiring - If a transducer reading is not within a reasonable range of gauge reading, check wires to sensors for short • For CSP: 1-3MSM-21, 1-3MSM-9, and 1-3MSM-32 • For EVOP: 1-3MSM-11, 1-3MSM-9, AND 1-3MSM-22 • For CDP: 1-3MSM-20, 1-3MSM-9, and 1-3MSM-31 • For ECOP: 1-3MSM-10, 1-3MSM-9, AND 1-3MSM-33 3. Check Power Supply Enable Circuit - Check wires to sensor for short. Check wiring from DM-7 to 1- 3MSM-35 (including SP-31). 4. Replace Main Stepper Module - Download data and replace Main Stepper module. For complete Main Stepper module replacement instructions refer to Section 5.5.2.