Cooling fan
Common VFD, drive, UPS, and cabinet overheating failure point.
Sun Hydraulics Fault Codes - Quick Reference
Sun Hydraulics (now Helios Technologies) manufactures screw-in hydraulic cartridge valves and Enovation Controls (Murphy) electronic systems for mobile and industrial hydraulics. Faults appear on MurphyLink displays or CAN bus diagnostics.
| Fault | Meaning | Quick Fix |
|---|---|---|
| Supply Voltage Low | Battery or supply below threshold | Check supply voltage at module |
| Supply Voltage High | Over-voltage on power input | Check alternator or power supply |
| Solenoid Open Circuit | Valve solenoid disconnected or failed | Check coil and wiring |
| Solenoid Short Circuit | Valve coil shorted | Replace coil |
| Sensor Signal Low | Pressure or position sensor below range | Check sensor supply and wiring |
| Sensor Signal High | Sensor above range | Check sensor and calibration |
| CAN Bus Fault | Communication lost on CAN network | Check CAN wiring and termination |
| Temperature High | Controller or oil temp exceeded | Check cooling, reduce duty cycle |
| Calibration Required | Setup procedure needed | Run calibration routine |
| Output Overcurrent | Output channel drawing too much current | Check load wiring |
Most Common Faults
Solenoid Open Circuit
The most common electrohydraulic fault on Sun/Helios systems. Vibration, moisture, and heat cycling cause solenoid connector failures. Check the DT or Deutsch connector pins before replacing the solenoid - bent or pushed-back pins are the leading cause of open circuit faults on mobile equipment.
CAN Bus Fault
Sun Hydraulics controllers on CAN networks require proper 120-ohm termination resistors at both ends of the CAN bus. A missing or failed terminator causes intermittent or total communication loss. Measure CAN HI to CAN LO - you should read approximately 60 ohms (two 120-ohm resistors in parallel) with power off.
Sensor Signal Low/High
Sun proportional hydraulic systems often use 0.5–4.5VDC ratiometric pressure sensors. A reference supply failure causes all sensors to read low simultaneously. Check the 5V sensor supply pin at the controller connector first before replacing sensors.
Temperature High
In mobile equipment, hydraulic oil temperature control relies on adequate fan cooling of the reservoir and cooler. Check for air dam obstructions, bent cooler fins, or a failed thermostat that prevents the cooler from activating.
Parts Often Needed
| Part | Notes |
|---|---|
| Deutsch DT connector pins | Most common fault location |
| Solenoid coil (12VDC or 24VDC) | Replace on short/open |
| Pressure transducer | Replace on signal fault |
| CAN bus termination resistor | 120 ohm |
| Murphy display module | Replace on screen or power faults |
Need Replacement Parts?
Before ordering, match the commercial equipment part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
Enovation/Murphy controller calibration for load-sensing systems and proportional valve flow tuning requires factory documentation. Incorrect calibration causes erratic machine motion.