Case IH U85 – Transmission Control Module (TCM): Medium and low range synchronizer solenoid connectors swapped

This indicates an incorrect installation where the electrical connectors for the mid-range and low-range synchronizer solenoids have been plugged into the wrong valves.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• Puma 160
• Puma 165
• Puma 170
• Puma 185
• Puma 200
• Puma 215
• Puma 225
• Puma 230 CVX
• Maxxum 110
• Maxxum 115
• Maxxum 120
• Maxxum 125
• Maxxum 130
• Maxxum 135
• Maxxum 140
• Maxxum 145
• Steiger
• CVX

1. 1

   Visually trace the transmission wiring harness to the medium and low range synchronizer solenoids to verify if the connectors are crossed or swapped (Primary cause for U85).

2. 2

   Test the synchronizer solenoids for proper resistance (typically around 10 Ohms) and check the wiring harness for any shorts to ground.

3. 3

   For U86 neutral errors, check the synchronizer potentiometer voltage and linkage by back-probing the electrical connector to ensure the signal is within allowable limits.

4. 4

   Verify there is no mechanical jamming within the synchronizer or internal transmission faults preventing the shift rail from reaching neutral.

1. 1

   Locate solenoids

   Locate the medium and low range synchronizer solenoids on the transmission control valve block.

2. 2

   Disconnect connectors

   Disconnect the swapped electrical connectors from both solenoids.

3. 3

   Re-route connectors

   Re-route and re-connect the connectors to their correct respective solenoids.

4. 4

   Replace defective component

   If diagnosing U86 and the potentiometer or solenoid is found to be faulty during the diagnostic checks, replace the defective component.

5. 5

   Clear error codes

   Clear the error codes from the TCM using the H-Menu or diagnostic tool.

6. 6

   Test system

   Test the system for normal operation.

7. 7

   Perform calibration

   Perform a transmission calibration procedure. Note that transmission oil temperature must typically be between 10°C and 60°C (or above 50°C depending on the specific model) to successfully complete the calibration.