Merlo 18 – CDC: Telescopic Arm Extension Sensor Fault

The signal from the telescopic arm extension sensor is outside the normal operating range of 0.5 to 4.5 volts. This prevents the main control unit from accurately calculating the telescopic reach of the boom, which leads to the immediate activation of safety overload lockouts and the cessation of boom operations.

• Turbofarmer
• Panoramic
• Multifarmer
• ROTO

1. 1

   Visually inspect the sensor (cable reel unit) for any visible damage, such as a snapped wire or damage to the recoil spring.

2. 2

   Inspect the wiring harness and connectors between the sensor and the control unit for any signs of damage, corrosion, open circuits, or short circuits.

3. 3

   Connect a MerloDiag tool and use the 'UGSB 1-2-15' test module to check live data from the telescopic arm extension sensor to confirm if the voltage is outside the 0.5-4.5V range.

1. 1

   Prepare machine for service

   Ensure the machine is on level ground with the boom fully retracted and the engine turned off.

2. 2

   Locate and inspect sensor

   Locate the telescopic arm extension sensor (cable reel assembly), typically at the rear of the boom. Gain access and perform a thorough inspection of the unit and its connections.

3. 3

   Test sensor output manually

   If a diagnostic tool is not available, have a qualified technician test the sensor's output using a multimeter by back-probing the connector while the system is powered on.

4. 4

   Replace faulty sensor

   If determined to be faulty, disconnect the electrical connector, unbolt the cable reel assembly from its mounting point, install the new sensor (ensuring correct cable routing), and reconnect the electrical connector.

5. 5

   Calibrate new sensor

   After replacement, perform a calibration procedure using the MerloDiag diagnostic tool to ensure the control system recognizes the new sensor and its range of motion.