Massey Ferguson 00.X.38 – Dash: Signal Voltage From Engine Speed Sensor Is Too High

The control module is receiving an electrical signal from the engine speed (RPM) sensor that exceeds the expected maximum voltage threshold, which usually points to a short circuit to power, a faulty sensor, or a wiring harness issue.

• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S
• Tier 4 (2015-2021)
• 5710 SL
• 5711 SL
• 5712 SL
• 5713 SL
• 6712 S
• 6713 S
• 6715 S
• 6716 S
• 6718 S
• 8727
• 8730
• 8732
• 8735
• 8737

1. 1

   Visually inspect the engine speed sensor and connector pins for corrosion, moisture, or physical damage

2. 2

   Perform a resistance test with the tractor stopped and the sensor disconnected at ambient temperature (should read 450 Ohms +/- 20 Ohms)

3. 3

   Check for an alternating voltage output from the sensor when the engine/gear is turning

4. 4

   Inspect the wiring harness continuity between the sensor and the Dash module, specifically looking for a short circuit to a 12V power source

1. 1

   Disconnect Power

   Always disconnect the battery before beginning installation to prevent ECU damage or electrical spikes.

2. 2

   Locate the Sensor

   Locate the engine speed sensor on the engine block/flywheel housing (note: depending on the exact model and chassis configuration, access may be tight and occasionally requires removing a tire or shielding for clearance).

3. 3

   Remove the Faulty Sensor

   Unplug the wiring harness connector and unbolt the sensor from its mounting point.

4. 4

   Install the New Sensor

   Insert the new sensor. Crucial step: Ensure the proper air gap is maintained according to your specific engine's manual, as magnetic pickup sensors require a precise gap to deliver clean RPM signals.

5. 5

   Reconnect

   Securely bolt the sensor in place and push the electrical connector until it clicks and locks fully into place.

6. 6

   Clear Codes

   Reconnect the battery. Use a diagnostic tool to clear the stored 00.X.38 fault code from the Dash module and run the tractor to verify the sensor is reading RPMs accurately.