Case IH U86 – Transmission Control Module (TCM) or GCM2: Medium/Reverse Range Synchronizer Neutral Error

The transmission system has detected that the medium/reverse range synchronizer is not in its expected neutral position.

• MXM
• Case IH MXM 120
• Case IH MXM 130
• Case IH MXM 140
• Case IH MXM 155
• Case IH MXM 175
• Case IH MXM 190
• Case IH Puma 165
• Case IH Puma 180
• Case IH Puma 195
• Case IH Puma 210
• Case IH Puma 225
• Case IH Steiger Series

1. 1

   Check the synchronizer movement in the HL (High/Low) range to see if it is physically returning to neutral.

2. 2

   Inspect the potentiometer for faults, and check for a wiring issue or damaged linkage connected to it.

3. 3

   Check for internal mechanical failure (e.g., a jammed synchronizer) if the potentiometer and linkage are functioning correctly.

1. 1

   Inspect and Replace Electrical Components

   If the diagnostic checks reveal a faulty synchronizer potentiometer or damaged linkage, replace the affected components.

2. 2

   Address Mechanical Faults

   If the potentiometer is fine but the synchronizer is jammed or damaged, the transmission will need to be opened to replace the internal medium/reverse synchronizer.

3. 3

   Clear the Code

   Once the physical repair is completed, clear the U86 error code from the TCM.

4. 4

   Test Operation

   Test the transmission system to ensure normal operation.

5. 5

   Recalibrate the Transmission

   Perform a transmission calibration procedure. You will need to monitor the display for calibration messages (e.g., "CF" indicates the calibration procedure completed successfully, while "CH" or "CL" indicate oil temperature warnings that must be addressed before proceeding).