Case IH U87 – Transmission Control Module (TCM): Low/High Range Synchronizer Neutral Error

This code indicates that the transmission control system detects that the low/high range synchronizer is not in the neutral position when it is expected to be, or the system cannot verify its neutral position.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• Maxxum Series
• Puma Series
• TM Series (TM115 - TM165)
• T7 Series

1. 1

   Check the synchronizer movement in High/Low (H/L). Inspect the external linkage connected to the synchronizer potentiometer for physical damage, binding, or loose connections.

2. 2

   Inspect the wiring harness and connectors leading to the synchronizer potentiometer for shorts, open circuits, or swapped connectors.

3. 3

   Perform HF Synchronizer Potentiometer Check (Diagnostic Mode): Ensure the engine is running, the transmission is in neutral, and the clutch is released. Enter the transmission diagnostic/test mode. Press and hold the downshift button to display the reverse position (approx. 75%). Press and hold the upshift button for the forward position (approx. 25%). If the values are erratic, out of range, or do not change, the potentiometer or linkage is likely faulty.

1. 1

   Address the Root Cause

   Based on the diagnostic checks, replace the faulty synchronizer potentiometer, repair the damaged linkage, or (if the potentiometer and linkage are fine) split the tractor to repair the internal mechanical binding/jamming of the synchronizer.

2. 2

   Clear the Code

   Once the physical repair is complete, clear the U87 error code from the TCM memory.

3. 3

   Recalibrate the Transmission

   Perform a transmission synchronizer and clutch calibration. The TCM needs to relearn the new potentiometer voltage values for the neutral, low, and high positions.

4. 4

   Test the System

   Test drive the tractor, shifting through all ranges to ensure the synchronizer engages and returns to neutral properly without throwing codes.