Case IH U121 – Electronic Park Lock (EPL) module, Transmission Control Unit (TCU), or Vehicle Control Unit (VCU): Inclinometer calibration procedure not OK

The tractor's onboard diagnostic system attempted to calibrate the inclinometer (the tilt/inclination sensor used for leveling, draft control, and electronic park lock systems) but the procedure failed to complete successfully or the sensor's readings were rejected.

• Puma 125
• Puma 130
• Puma 145
• Puma 160
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225 CVX
• Farmall 40
• Farmall 45
• Farmall 50
• Farmall 100
• Farmall 115U
• Maxxum
• Steiger

1. 1

   Verify the vehicle is completely stationary (a moving tractor will trigger a related U123 code)

2. 2

   Check the ground level to ensure the vehicle is parked on completely flat, level ground

3. 3

   Disconnect and remove any rear attachments or heavy implements that alter the tractor's resting stance and pitch

4. 4

   Verify the correct OEM wheels and tires are installed and properly inflated

5. 5

   Inspect the physical installation of the inclinometer to ensure it is securely mounted, not broken, and not installed crookedly

1. 1

   Relocate tractor

   Relocate the tractor to a known flat, level concrete surface.

2. 2

   Disconnect implements

   Disconnect all implements from the rear remotes and drop any heavy attachments.

3. 3

   Verify tires and wheels

   Verify that tire pressures are even and wheel sizes match the manufacturer's specifications.

4. 4

   Inspect sensor mounting

   Inspect the inclinometer sensor mounting on the chassis for damage, debris, or looseness. Secure the mounting hardware if necessary.

5. 5

   Navigate to Calibration Menu

   Turn the key switch on and use the ICU/keypad (or the 'up', 'down', and 'menu' keys) to navigate to the 'H Menu' (Calibration Menu) for the transmission/EPL system.

6. 6

   Restart calibration

   Restart the inclinometer calibration procedure as prompted by the cluster display.

7. 7

   Store calibration values

   If the calibration completes successfully, turn the key switch to the OFF position to store the new calibration values in the module's memory.

8. 8

   Replace inclinometer if defective

   If the calibration fails again with U121 (or U120), the inclinometer sensor itself is internally defective and must be replaced.

9. 9

   Install new inclinometer and recalibrate

   Install the new inclinometer, ensure it is mounted perfectly flat to the bracket, and repeat the H-Menu calibration procedure.