John Deere 1638.02 – HCC / HCU, SCU, SCO: Calibration Fault / Hydraulic Oil Temperature Low

Generated when an operator or technician attempts to calibrate the hitch or hydraulic control unit while the tractor's hydraulic oil temperature is below the required threshold.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5090M
• 5100M
• 5100MH
• 5100ML
• 5115M
• 5065M
• 5075M
• 5085M
• 5115ML
• 5095M
• 5095MH
• 5105M
• 5015ML
• 9230
• 9330
• 9430
• 9530
• 9630

1. 1

   Verify actual oil temperature using the tractor's display monitor or a diagnostic tool

2. 2

   Perform a sensor sanity check: if the tractor has been working under heavy load but the sensor still reads below 50°C (122°F), the hydraulic oil temperature sensor or its wiring circuit may be faulty

1. 1

   Warm Up the Hydraulic System

   Start the tractor and operate the hydraulic functions (e.g., cycling the loader, dead-heading a remote valve briefly, or driving the tractor) to build heat in the hydraulic oil.

2. 2

   Monitor Temperature

   Watch the temperature readout until the hydraulic oil exceeds 50°C (122°F).

3. 3

   Recalibrate

   Once the oil is within the correct temperature range, restart the Hitch Control Unit (HCC) calibration process.

4. 4

   Inspect Sensor

   If the oil is physically hot but the calibration still fails due to this code, locate the hydraulic oil temperature sensor on the transmission/hydraulic housing. Inspect the wiring harness for damage, and replace the sensor if it is reading out of range.