John Deere 636.06 – ECU: Camshaft Position Circuit Has Low Resistance

The controller detects abnormally high current on the camshaft position sensor wiring, which indicates that the sensor's harness is shorted to ground or the sensor itself has an internal short. The primary symptom is an extended or excessive cranking time.

• 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
• 7R series
• 8R series
• 310J
• 310G
• 310K
• 410J
• 410K
• E240LC
• 120C
• 160DLC
• 200CLC
• 4930 Self-Propelled Sprayer

1. 1

   Inspect the wiring harness running from the ECU to the camshaft position sensor for chafed insulation, melted wires, or pinched areas where the harness might be shorting directly to the engine block or ground.

2. 2

   Perform a sensor swap test: Clear the active codes, swap the camshaft position sensor with the crankshaft position sensor (they are typically the same part), and attempt to start the machine. If the fault code changes to a 637.XX code, the sensor is internally shorted. If the code remains 636.06, the fault lies within the wiring harness or the ECU.

1. 1

   Power Down

   Turn off the machine and remove the key.

2. 2

   Locate the Sensor

   Locate the camshaft position sensor, which is typically mounted on the front of the camshaft drive gear/timing cover.

3. 3

   Disconnect and Inspect

   Unplug the 3-pin connector from the sensor. Check the connector pins for corrosion, moisture, or damage.

4. 4

   Repair Wiring (If Applicable)

   If the swap test proved the wiring is at fault, trace the short to ground using a multimeter. Repair or splice the damaged section of the engine wiring harness and wrap it in high-heat loom.

5. 5

   Replace Sensor (If Applicable)

   If the swap test proved the sensor is internally shorted, unbolt the faulty sensor and install the replacement.

6. 6

   Reassemble and Clear Codes

   Plug the sensor connector back in, ensuring the locking tab clicks into place. Turn the key on, clear the stored ECU codes, and start the engine to verify that the long-cranking symptom is resolved.