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Understanding the intermittent loss of auxiliary hydraulics on the Case TR320 requires a blend of electrical diagnostics, hydraulic logic, and knowledge of the machine’s design history. This article explores the issue in depth, expands on missing technical context, and provides practical solutions supported by real‑world experience.
Background of the Case TR320
The Case TR320 compact track loader was introduced as part of Case Construction Equipment’s push into Tier 4‑compliant, high‑efficiency machines in the early 2010s. Case, founded in 1842, has a long history of building agricultural and construction machinery, and by the time the TR‑series was released, the company had already sold millions of machines worldwide.
The TR320 was positioned as a mid‑frame track loader with strong hydraulic performance, boasting:
Symptoms of the Auxiliary Hydraulic Failure
Operators reported a very specific pattern:
Key Components Involved
To understand the failure, it helps to break down the relevant components:
Why the Failure Happens
Based on field experience and the machine’s design, the most likely causes include:
Detailed Diagnostic Approach
1. Inspect Joystick Wiring Thoroughly
Even if continuity appears normal, flex the harness while testing.
Common failure points include:
Use an inline jumper to monitor voltage at the solenoids.
If voltage drops to zero instantly on both sides, the module is shutting down.
3. Check All Grounds
Clean every ground point and inspect inline ground fuses.
A corroded ground can mimic a short and trigger module shutdown.
4. Inspect Connectors for Water
Dry them thoroughly and apply dielectric grease.
Snow‑service machines often show moisture‑related failures.
5. Test the Handle Switch Assembly
Some operators reported that replacing the joystick handle permanently resolved the issue.
This suggests internal switch or wiring degradation.
Additional Technical Notes
Real‑World Example
A contractor in Alberta reported that his TR‑series loader would lose auxiliary hydraulics whenever he operated a snowblower attachment. After months of troubleshooting, the root cause was found to be a single joystick wire broken inside the insulation. The wire made contact when the joystick was tilted forward but separated when centered—exactly matching the intermittent failure pattern.
This mirrors the behavior described in many field cases.
Recommended Solutions
Preventive Measures
To reduce recurrence:
Conclusion
The Case TR320’s auxiliary hydraulic failure is rarely caused by the PWM module itself. Instead, the issue almost always traces back to wiring fatigue, grounding faults, or moisture intrusion—especially in machines used for snow removal. With systematic diagnostics and attention to the machine’s known weak points, the problem can be resolved permanently.
Background of the Case TR320
The Case TR320 compact track loader was introduced as part of Case Construction Equipment’s push into Tier 4‑compliant, high‑efficiency machines in the early 2010s. Case, founded in 1842, has a long history of building agricultural and construction machinery, and by the time the TR‑series was released, the company had already sold millions of machines worldwide.
The TR320 was positioned as a mid‑frame track loader with strong hydraulic performance, boasting:
- Operating capacity around 3,200 lbs
- Hydraulic flow options up to 32.4 GPM (high‑flow)
- Electronic‑controlled proportional auxiliary hydraulics
- Electro‑hydraulic joysticks with integrated switches
Symptoms of the Auxiliary Hydraulic Failure
Operators reported a very specific pattern:
- The auxiliary hydraulics work normally at first.
- Suddenly, both solenoids lose power at the same moment.
- The system becomes completely unresponsive in both directions.
- Resetting the hydraulic enable function temporarily restores operation.
- The failure repeats intermittently and unpredictably.
Key Components Involved
To understand the failure, it helps to break down the relevant components:
- Proportional Auxiliary Solenoids
These control flow direction and modulation. They require stable voltage and PWM (pulse‑width modulation) signals.
- PWM Control Module
Converts joystick commands into modulated electrical output. It also includes protective logic that shuts down the circuit if it detects a short or open.
- Joystick Wiring Harness
Contains fine‑gauge wires that flex constantly during operation. These are prone to internal breaks.
- Ground Circuits and Ground Fuses
Case machines often use inline ground fuses hidden in the rear harness. Corrosion or moisture can cause intermittent open circuits.
- Hydraulic Enable System
Resetting the “operate” button or lifting the lap bar reinitializes the hydraulic logic, which temporarily restores function.
Why the Failure Happens
Based on field experience and the machine’s design, the most likely causes include:
- Internal wire breaks inside the joystick harness
Continuity tests may pass because the wire touches intermittently, but vibration causes momentary disconnects.
- Moisture intrusion in connectors
Machines used for snow removal often accumulate water inside sealed connectors, leading to corrosion.
- PWM module protective shutdown
When the module detects an abnormal load, it disables both solenoids simultaneously.
- Poor grounding
Case machines are known for hidden ground fuses that corrode and cause intermittent faults.
Detailed Diagnostic Approach
1. Inspect Joystick Wiring Thoroughly
Even if continuity appears normal, flex the harness while testing.
Common failure points include:
- Near the base of the joystick
- Inside the molded handle
- Where the harness enters the main loom
Use an inline jumper to monitor voltage at the solenoids.
If voltage drops to zero instantly on both sides, the module is shutting down.
3. Check All Grounds
Clean every ground point and inspect inline ground fuses.
A corroded ground can mimic a short and trigger module shutdown.
4. Inspect Connectors for Water
Dry them thoroughly and apply dielectric grease.
Snow‑service machines often show moisture‑related failures.
5. Test the Handle Switch Assembly
Some operators reported that replacing the joystick handle permanently resolved the issue.
This suggests internal switch or wiring degradation.
Additional Technical Notes
- PWM (Pulse‑Width Modulation)
A method of controlling hydraulic solenoids by rapidly switching voltage on and off.
If the module detects abnormal resistance, it cuts output to protect the circuit.
- Solenoid Coil Resistance
Typical values range from 6–12 ohms depending on the model.
A coil outside this range may trigger shutdown.
- Ground Fuse Design
Case uses sealed inline fuses on the negative side of the circuit.
When corroded, they cause intermittent open circuits that are notoriously hard to diagnose.
Real‑World Example
A contractor in Alberta reported that his TR‑series loader would lose auxiliary hydraulics whenever he operated a snowblower attachment. After months of troubleshooting, the root cause was found to be a single joystick wire broken inside the insulation. The wire made contact when the joystick was tilted forward but separated when centered—exactly matching the intermittent failure pattern.
This mirrors the behavior described in many field cases.
Recommended Solutions
- Replace the joystick handle assembly if intermittent wiring is suspected.
- Clean and re‑establish all ground connections.
- Inspect and replace corroded inline ground fuses.
- Dry and reseal all connectors exposed to moisture.
- Test the PWM module only after confirming wiring integrity.
- Add protective loom or strain relief to joystick harnesses to prevent future breaks.
Preventive Measures
To reduce recurrence:
- Avoid pressure‑washing electrical connectors.
- Apply dielectric grease before winter seasons.
- Inspect joystick harnesses annually.
- Add moisture‑barrier tape around vulnerable connectors.
- Keep the cab sealed during snow operations to reduce condensation.
Conclusion
The Case TR320’s auxiliary hydraulic failure is rarely caused by the PWM module itself. Instead, the issue almost always traces back to wiring fatigue, grounding faults, or moisture intrusion—especially in machines used for snow removal. With systematic diagnostics and attention to the machine’s known weak points, the problem can be resolved permanently.
