Case IH U52 – Transmission Controller / Electronic Management Unit (EMU): Constant Engine RPM (CERPM) Switch Switched More Than 3 Times

A calibration error occurring during Transmission or Electronic Draft Control (EDC) calibration setup. The system logs this code if the operator presses the Constant Engine RPM switch more than three times while the calibration is actively running, which interrupts or invalidates the calibration parameters.

• Puma/Mid Range Magnum
• MXM
• Case IH MXM Series (MXM 120, MXM 130, MXM 140, MXM 155, MXM 175, MXM 190)
• Case IH Puma Series (Puma 115, 125, 140, 155, 210)
• Case IH Steiger & Magnum Series

1. 1

   Verify if the operator or technician accidentally bumped the CERPM switch during transmission or clutch calibration

2. 2

   Check the CERPM switch physically to ensure the rocker switch is not stuck in the depressed position due to dirt or debris

3. 3

   Use the HE menu function in the transmission module via the digital display to verify engine speed detection and ensure the switch isn't sending a continuous shorted signal

1. 1

   Clear the Error

   Turn the key switch to the OFF position to clear the active calibration mode.

2. 2

   Prepare for Calibration

   Repeat the start procedure for the Transmission/EDC calibration. Ensure the tractor is at the correct operating temperature (usually between 20°C–50°C for MXM transmissions).

3. 3

   Perform Calibration

   Initiate the calibration sequence again. Do not touch the Constant Engine RPM switch during the entire calibration process. If the calibration completes successfully (displaying 'END'), no further repair is needed.

4. 4

   Access the Switch

   If the code immediately returns without operator input, disconnect the tractor's battery. Remove the retaining screws for the right-hand operator console/armrest where the CERPM switch is located and lift the console cover to expose the wiring harness.

5. 5

   Test the Switch

   Unplug the connector from the back of the Constant Engine RPM switch. Test the switch with a multimeter for continuity.

6. 6

   Replace the Switch

   If it shows continuity without being pressed (shorted), pop the switch out of the bezel and install a replacement.

7. 7

   Reassemble and Calibrate

   Reassemble the console, reconnect the battery, and perform the transmission calibration.