Massey Ferguson E9071 – Engine Control Unit (ECU): Crankshaft speed sensor. Crankshaft speed signal, too many pulses.

The control module is receiving an erratic, noisy, or excessively high-frequency signal from the crankshaft speed sensor that does not align with the engine's actual mechanical RPM. This is typically caused by a failing sensor, metallic debris on the magnetic sensor tip, or electrical interference/chafing in the wiring harness introducing false pulses into the signal wire.

• 8600 Series
• 8670
• 8690
• 5400 Series
• 6400 Series
• 7400 Series

1. 1

   Inspect the wiring harness and connector leading to the crankshaft speed sensor for chafed insulation, exposed wires, or a loose connection that could introduce electrical noise or false pulses.

2. 2

   Remove the crankshaft speed sensor and inspect the magnetic tip for accumulated metallic shavings or debris that could distort the magnetic field.

3. 3

   Check the sensor mounting to ensure it is securely bolted flush against the engine block, as a loose sensor can vibrate and alter the air gap to the reluctor wheel.

4. 4

   Use an oscilloscope (if available) to monitor the sensor's signal output while cranking or running, looking for irregular square waves or spikes that confirm the 'too many pulses' condition.

1. 1

   Preparation

   Park the tractor on a level surface, turn off the ignition, and disconnect the negative battery terminal to prevent electrical damage.

2. 2

   Locate the Sensor

   Locate the crankshaft speed sensor on the engine block. It is typically mounted near the front crankshaft pulley or at the rear near the flywheel housing, depending on the specific Sisu/Perkins engine variant.

3. 3

   Disconnect Harness

   Carefully depress the locking tab and unplug the electrical connector from the sensor.

4. 4

   Remove the Sensor

   Remove the single retaining bolt securing the sensor to the block. Gently twist and pull the sensor out of its bore.

5. 5

   Clean the Bore

   Wipe the mounting surface and the sensor bore with a clean rag. Ensure no dirt or old O-ring material is left behind, as the new sensor must seat perfectly flat to maintain the correct air gap.

6. 6

   Install the New Sensor

   Lubricate the O-ring on the new sensor with a small amount of clean engine oil. Push the sensor into the bore and install the retaining bolt. Tighten to OEM torque specifications (do not overtighten, as this can crack the plastic sensor housing).

7. 7

   Reconnect and Clear Codes

   Reconnect the electrical harness and the battery. Turn the ignition on and use a diagnostic scan tool to clear the E9071 fault code. Start the engine and verify that the RPM reads smoothly on the dash and the code does not return.