09-29-2025, 01:09 PM
The Bobcat T590 and Its Electronic Control System
The Bobcat T590 compact track loader is part of Bobcat’s M-Series, introduced to meet the growing demand for versatile, electronically enhanced machines in the compact equipment market. With a rated operating capacity of 2,100 pounds and a turbocharged diesel engine producing around 66 horsepower, the T590 is widely used in landscaping, construction, and utility work. Its advanced control system includes multiple electronic modules that manage engine performance, hydraulic functions, and attachment operations.
Bobcat, founded in North Dakota in 1947, pioneered the skid-steer loader and has since sold millions of units worldwide. The M-Series marked a shift toward integrated diagnostics and CAN bus communication, allowing for real-time fault detection and streamlined troubleshooting.
Understanding the M4404 Warning Code
When a Bobcat T590 displays the M4404 warning code, it indicates a failure in communication with the auxiliary hydraulic control system. This typically means that the machine cannot detect or interact with the module responsible for managing auxiliary functions—such as powering hydraulic attachments like augers, grapples, or trenchers.
Symptoms include:
Primary Diagnostic Steps
To resolve the M4404 code, technicians should follow a structured diagnostic approach:
A technician in Pennsylvania encountered the M4404 code on a T590 with under 800 hours. After checking fuses and relays, he suspected a short in the wiring harness but found no visible damage. A dealer suggested the ECU was likely at fault, but without a way to test it, the operator hesitated to schedule a service call.
Another operator in Indiana resolved a similar issue by reseating the connectors on the auxiliary controller. The machine had recently been pressure washed, and moisture had entered the connector housing. After drying and sealing the contacts, the warning code cleared and attachments resumed normal function.
Preventive Measures and Best Practices
To reduce the risk of auxiliary communication failure:
Modern compact loaders increasingly rely on electronic modules and CAN bus systems to manage hydraulic and engine functions. While this improves efficiency and diagnostics, it also introduces new failure modes. Manufacturers now offer remote monitoring and software updates to address electronic faults.
In 2024, a fleet operator in Ohio retrofitted his Bobcat units with moisture-resistant connector kits and saw a 70% reduction in electrical fault codes over the following year. These kits included sealed boots, heat-shrink tubing, and upgraded harness insulation.
Conclusion
The M4404 auxiliary no communication code on a Bobcat T590 is a common but solvable issue. By methodically inspecting fuses, connectors, solenoids, and wiring, operators can often restore functionality without replacing expensive components. As compact equipment continues to evolve, understanding the interplay between hydraulics and electronics becomes essential for efficient troubleshooting and long-term reliability. With proper care and awareness, machines like the T590 can deliver consistent performance across a wide range of demanding applications.
The Bobcat T590 compact track loader is part of Bobcat’s M-Series, introduced to meet the growing demand for versatile, electronically enhanced machines in the compact equipment market. With a rated operating capacity of 2,100 pounds and a turbocharged diesel engine producing around 66 horsepower, the T590 is widely used in landscaping, construction, and utility work. Its advanced control system includes multiple electronic modules that manage engine performance, hydraulic functions, and attachment operations.
Bobcat, founded in North Dakota in 1947, pioneered the skid-steer loader and has since sold millions of units worldwide. The M-Series marked a shift toward integrated diagnostics and CAN bus communication, allowing for real-time fault detection and streamlined troubleshooting.
Understanding the M4404 Warning Code
When a Bobcat T590 displays the M4404 warning code, it indicates a failure in communication with the auxiliary hydraulic control system. This typically means that the machine cannot detect or interact with the module responsible for managing auxiliary functions—such as powering hydraulic attachments like augers, grapples, or trenchers.
Symptoms include:
- Attachments not responding to joystick commands
- No hydraulic flow at the auxiliary couplers
- Warning light or audible alert on the display
- Machine otherwise operating normally
Primary Diagnostic Steps
To resolve the M4404 code, technicians should follow a structured diagnostic approach:
- Inspect Fuses and Relays
Check the fuse panel for blown fuses related to the auxiliary system. Replace any faulty components and test for continuity.
- Verify Connector Integrity
Examine the connectors on the auxiliary controller. Ensure they are fully seated, free of corrosion, and not damaged. Use dielectric grease to protect against moisture.
- Test the Electric Solenoid
The solenoid valve controls hydraulic flow to the auxiliary couplers. A failed solenoid can prevent activation. Apply voltage directly to test response.
- Check CAN Bus Communication
Use a diagnostic tool to verify that the auxiliary module is visible on the CAN network. A missing module may indicate a wiring fault or ECU failure.
- Inspect Wiring Harness
Look for pinched, frayed, or chewed wires—especially near the cab floor, under the seat, and around the hydraulic block.
- Evaluate ECU Functionality
If all other components test normal, the ECU may be faulty. Replacement should be considered only after ruling out simpler causes.
A technician in Pennsylvania encountered the M4404 code on a T590 with under 800 hours. After checking fuses and relays, he suspected a short in the wiring harness but found no visible damage. A dealer suggested the ECU was likely at fault, but without a way to test it, the operator hesitated to schedule a service call.
Another operator in Indiana resolved a similar issue by reseating the connectors on the auxiliary controller. The machine had recently been pressure washed, and moisture had entered the connector housing. After drying and sealing the contacts, the warning code cleared and attachments resumed normal function.
Preventive Measures and Best Practices
To reduce the risk of auxiliary communication failure:
- Avoid pressure washing near electronic modules and connectors
- Use dielectric grease on all exposed terminals
- Inspect wiring harnesses quarterly for wear or rodent damage
- Keep diagnostic tools on hand for CAN bus verification
- Log fault codes and track recurrence for pattern analysis
Modern compact loaders increasingly rely on electronic modules and CAN bus systems to manage hydraulic and engine functions. While this improves efficiency and diagnostics, it also introduces new failure modes. Manufacturers now offer remote monitoring and software updates to address electronic faults.
In 2024, a fleet operator in Ohio retrofitted his Bobcat units with moisture-resistant connector kits and saw a 70% reduction in electrical fault codes over the following year. These kits included sealed boots, heat-shrink tubing, and upgraded harness insulation.
Conclusion
The M4404 auxiliary no communication code on a Bobcat T590 is a common but solvable issue. By methodically inspecting fuses, connectors, solenoids, and wiring, operators can often restore functionality without replacing expensive components. As compact equipment continues to evolve, understanding the interplay between hydraulics and electronics becomes essential for efficient troubleshooting and long-term reliability. With proper care and awareness, machines like the T590 can deliver consistent performance across a wide range of demanding applications.
