Case IH U70 – Electronic System / Transmission Controller: PTO twist sensor not calibrated

The calibration value recorded by the controller during the setup procedure was either too high or too low, or the calibration procedure was interrupted and not completed successfully.

• Puma/Mid Range Magnum
• Puma 140
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225
• Puma 260
• Puma CVX
• Magnum MX210
• Magnum MX230
• Magnum MX255
• Magnum MX285
• Magnum 235-340 (Series 4)
• Maxxum MXM

1. 1

   Check PTO Switch Position: Ensure the PTO switch was not accidentally turned ON or left in the 'start' position during a previous calibration attempt.

2. 2

   Check for Circuit Faults: Verify there are no active U58 (PTO twist sensor open circuit) or U59 (PTO twist sensor short circuit) codes. If these are present, the wiring harness must be repaired before calibration is possible.

3. 3

   Operating Conditions: Ensure the tractor is fully warmed up to normal operating temperature. Make sure the air conditioning and all electrical/hydraulic applications are turned off/deselected, as parasitic loads can interfere with the calibration process.

1. 1

   Warm up vehicle

   Warm up the vehicle to operating temperature.

2. 2

   Turn ignition ON

   Turn the ignition key switch to the ON position.

3. 3

   Check PTO switch

   Ensure the PTO enable switch is turned OFF.

4. 4

   Access calibration menu

   Access the tractor's calibration menu (typically via the lower central instrument display). Depending on the model, you will use the 'dimming', 'h' (hours), and 'm' (minutes) buttons to navigate to the 'HH' menus and select the specific 'ch_' (channel) for the PTO twist sensor.

5. 5

   Execute calibration

   Execute the calibration. If the sensor is healthy and the driveline has no mechanical binding, the new calibration value will be stored, and the U70 code will clear.

6. 6

   Inspect wiring harness

   If the calibration fails again (reporting a value too high or too low), inspect the wiring harness at the PTO twist sensor for corrosion or damage.

7. 7

   Replace sensor

   If the wiring is intact and the calibration still fails, the PTO twist sensor is faulty and must be replaced. Repeat the calibration procedure after installing the new sensor.