John Deere 637.06 – Engine Control Unit (ECU): Issue With Signal From Crankshaft Position Sensor Low Resistance

The controller has detected a low resistance condition or a short to ground in the circuit for the crankshaft position sensor (also referred to as the engine timing sensor or speed sensor).

• 5085E
• 5090E
• 5090EL
• 5100E
• 5065M
• 5075M
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5095M
• 5095MH
• 5105M
• 5015ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 9230
• 9330
• 9430
• 9530
• 9630
• 6M-1654
• 6M-1854
• 6M-2104
• 9570 STS
• 9660 STS
• 9760 STS
• 4930

1. 1

   Visually inspect the wiring harness leading to the crankshaft position sensor for chafing, melting, or bare wires touching the engine block or frame.

2. 2

   Disconnect the sensor and inspect the pins on both the sensor side and the harness side for corrosion, moisture, or bent pins that could cause a short.

3. 3

   Use a multimeter to check the resistance of the sensor circuit. Test the signal wire for continuity to ground. If there is continuity to ground while the sensor is unplugged, the harness is shorted. If the harness tests fine, the internal coil of the sensor itself has likely failed (shorted internally).

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery to prevent electrical spikes.

2. 2

   Locate the Sensor

   Locate the crankshaft position sensor (timing sensor), typically mounted on the engine block near the crankshaft pulley or flywheel housing.

3. 3

   Repair Wiring (If Applicable)

   If the diagnostic checks revealed a short to ground in the wiring harness, repair the damaged section of the wire using proper splicing techniques and heat shrink, or replace the affected harness section.

4. 4

   Replace the Sensor (If Applicable)

   If the wiring is intact, the sensor is faulty. Remove the retaining bolt holding the sensor in place. Carefully pull the old sensor out of the engine block.

5. 5

   Install New Sensor

   Lubricate the O-ring on the new sensor with a small amount of clean engine oil. Insert the new sensor into the port and tighten the retaining bolt to the OEM torque specification.

6. 6

   Reconnect and Clear Codes

   Reconnect the sensor harness and the battery. Turn the key on and use a diagnostic tool to clear the inactive 000637.06 fault code. Start the engine to verify the code does not return and that engine RPM/timing is reading correctly.