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The Bobcat S185 and Its Electronic Control Legacy
The Bobcat S185 skid steer loader was one of the most popular models in Bobcat’s mid-2000s lineup, powered by a 56 hp Kubota V2003 diesel engine and offering a rated operating capacity of 1,850 lbs. Manufactured by the Bobcat Company (formerly Melroe), the S185 was part of a generation that introduced more sophisticated electronic control modules (ECMs) and sensor-based diagnostics. By 2010, Bobcat had sold over 500,000 skid steers globally, with the S185 consistently ranking among the top sellers due to its balance of power, maneuverability, and reliability.
The integration of digital fault codes into the loader’s control system allowed for more precise troubleshooting—but also introduced new challenges for field technicians unfamiliar with electronic diagnostics. One such code, 32-65, has puzzled many operators and mechanics due to its cryptic nature and limited documentation.
Terminology Explained
Error code 32-65 typically flags a reference voltage fault—specifically, the ECM is not detecting the expected 5V signal at pin A of the J1 connector. This voltage is critical for powering sensors such as throttle position, seat switch, and hydraulic pressure transducers. Without it, the ECM cannot interpret sensor data, and may default to safe mode or disable certain functions.
In one documented case, a technician found zero voltage at J1 pin A, confirming the ECM was not supplying the reference signal. This pointed to either an internal ECM fault, a shorted sensor pulling down the voltage, or a wiring issue between the ECM and the sensor network.
Common Causes and Diagnostic Path
Several scenarios can trigger this fault:
A fleet mechanic in Alberta encountered error 32-65 on a Bobcat S185 used for snow removal. The machine would intermittently lose throttle response and display the fault code. After hours of tracing wires, he discovered that a pressure sensor near the hydraulic manifold had failed internally, shorting the 5V line. Replacing the sensor restored normal operation.
He later added inline fuses to each sensor’s power feed, allowing future faults to be isolated without risking ECM damage. His advice: “Don’t assume the ECM is bad—start with the sensors. They’re cheaper and fail more often.”
Design Improvements and Preventive Measures
Modern Bobcat models have improved fault isolation by:
As equipment becomes more electronically controlled, fault codes like 32-65 will become more common. In 2022, over 70% of new compact loaders included ECM-based diagnostics. While this improves performance and safety, it also demands a new skill set from technicians—one that blends mechanical intuition with electrical troubleshooting.
Training programs now include modules on sensor theory, voltage tracing, and ECM logic. Manufacturers like Bobcat have begun offering mobile apps that decode fault codes and suggest repair paths, though field experience remains irreplaceable.
Conclusion
Error code 32-65 on the Bobcat S185 signals a loss of reference voltage—often due to a shorted sensor, damaged wiring, or ECM failure. While the code may seem cryptic, a systematic diagnostic approach can pinpoint the fault and restore machine function. As electronic systems continue to evolve, understanding the interplay between sensors, voltage, and control logic will be essential for keeping equipment running smoothly in the field.
The Bobcat S185 skid steer loader was one of the most popular models in Bobcat’s mid-2000s lineup, powered by a 56 hp Kubota V2003 diesel engine and offering a rated operating capacity of 1,850 lbs. Manufactured by the Bobcat Company (formerly Melroe), the S185 was part of a generation that introduced more sophisticated electronic control modules (ECMs) and sensor-based diagnostics. By 2010, Bobcat had sold over 500,000 skid steers globally, with the S185 consistently ranking among the top sellers due to its balance of power, maneuverability, and reliability.
The integration of digital fault codes into the loader’s control system allowed for more precise troubleshooting—but also introduced new challenges for field technicians unfamiliar with electronic diagnostics. One such code, 32-65, has puzzled many operators and mechanics due to its cryptic nature and limited documentation.
Terminology Explained
- ECM (Electronic Control Module): The onboard computer that monitors and controls engine and hydraulic functions.
- J1 Connector: A multi-pin plug on the ECM used for sensor input and power distribution.
- Reference Voltage: A stable 5V signal supplied by the ECM to sensors for accurate readings.
- Hall Effect Sensor: A magnetic sensor used to detect position or movement, often requiring a 5V reference.
Error code 32-65 typically flags a reference voltage fault—specifically, the ECM is not detecting the expected 5V signal at pin A of the J1 connector. This voltage is critical for powering sensors such as throttle position, seat switch, and hydraulic pressure transducers. Without it, the ECM cannot interpret sensor data, and may default to safe mode or disable certain functions.
In one documented case, a technician found zero voltage at J1 pin A, confirming the ECM was not supplying the reference signal. This pointed to either an internal ECM fault, a shorted sensor pulling down the voltage, or a wiring issue between the ECM and the sensor network.
Common Causes and Diagnostic Path
Several scenarios can trigger this fault:
- Sensor Short to Ground
A damaged sensor may internally short the 5V line to ground, causing the ECM to shut down the reference circuit to protect itself.
- Wiring Harness Damage
Chafed or pinched wires near the engine bay or under the seat can interrupt voltage delivery or create intermittent faults.
- ECM Internal Failure
A failed voltage regulator inside the ECM may prevent it from generating the 5V signal altogether.
- Corroded Connectors
Moisture ingress into the J1 plug or sensor connectors can cause resistance buildup or signal loss.
- Disconnect all sensors using the 5V reference and check voltage at J1 pin A. If voltage returns, reconnect sensors one at a time to identify the faulty unit.
- Inspect wiring harness for abrasion, especially near pivot points and heat sources.
- Use a breakout box or back-probe technique to measure voltage without disturbing connector integrity.
- Check ECM ground and power supply—low battery voltage or poor grounding can affect internal regulation.
- If no voltage is present with all sensors disconnected, ECM replacement may be necessary.
A fleet mechanic in Alberta encountered error 32-65 on a Bobcat S185 used for snow removal. The machine would intermittently lose throttle response and display the fault code. After hours of tracing wires, he discovered that a pressure sensor near the hydraulic manifold had failed internally, shorting the 5V line. Replacing the sensor restored normal operation.
He later added inline fuses to each sensor’s power feed, allowing future faults to be isolated without risking ECM damage. His advice: “Don’t assume the ECM is bad—start with the sensors. They’re cheaper and fail more often.”
Design Improvements and Preventive Measures
Modern Bobcat models have improved fault isolation by:
- Separating reference voltage circuits for critical and non-critical sensors.
- Adding diagnostic LEDs to ECMs for visual fault confirmation.
- Using waterproof connectors with gold-plated terminals to resist corrosion.
- Performing regular connector inspections and applying dielectric grease.
- Replacing sensors every 3–5 years in high-vibration environments.
- Installing surge protectors or voltage stabilizers if operating in areas with frequent battery fluctuations.
As equipment becomes more electronically controlled, fault codes like 32-65 will become more common. In 2022, over 70% of new compact loaders included ECM-based diagnostics. While this improves performance and safety, it also demands a new skill set from technicians—one that blends mechanical intuition with electrical troubleshooting.
Training programs now include modules on sensor theory, voltage tracing, and ECM logic. Manufacturers like Bobcat have begun offering mobile apps that decode fault codes and suggest repair paths, though field experience remains irreplaceable.
Conclusion
Error code 32-65 on the Bobcat S185 signals a loss of reference voltage—often due to a shorted sensor, damaged wiring, or ECM failure. While the code may seem cryptic, a systematic diagnostic approach can pinpoint the fault and restore machine function. As electronic systems continue to evolve, understanding the interplay between sensors, voltage, and control logic will be essential for keeping equipment running smoothly in the field.
