Case IH 13 – Transmission Control Module (ECM/TCU): UD_SW_ON_ERR (Up/Down Switch On Error)

The Transmission Control Module has detected both the Hi (Rabbit) and Lo (Turtle) buttons on the gearshift lever being pressed simultaneously for longer than 0.5 seconds.

• JXC
• Farmall JX
• Farmall JXU
• 70JX
• 75JX
• 80JX
• 90JX
• 100JX
• 110JX
• TN Series
• TNA Series
• TN60A
• TN70A
• TN75A
• TN85A
• TN95A
• TNDA
• TNSA
• NT75D
• T5050
• T5070

1. 1

   Verify with the operator if they accidentally pressed both the Hi and Lo buttons at the same time

2. 2

   Inspect the Hi/Lo buttons on the main gearshift lever for dirt, debris, or a broken internal spring causing a button to stick in the closed position

3. 3

   Test the wiring harness between the Hi/Lo switch and the Transmission ECM for a short to 12 volts on circuits leading to ECM connector 2, pin 3 (Hi button) or pin 22 (Lo button)

4. 4

   Check for chafing where the wires exit the gearshift lever tube and route under the cab floor

1. 1

   Power Down

   Turn the ignition key to the OFF position and disconnect the battery ground to ensure the system is depowered.

2. 2

   Access the Switch

   If the switch failed the mechanical or continuity test, carefully pry the cap off the gearshift knob or remove the screws securing the knob halves (depending on exact cab configuration).

3. 3

   Disconnect Wiring

   Trace the switch wiring down the shift lever shaft and disconnect the harness connector.

4. 4

   Replace or Repair

   If the switch is faulty: Install a new Speed Gearshift Control Lever knob/switch assembly. Route the new wiring down the lever shaft and plug it into the harness. If the wiring is shorted: Locate the pinched or chafed wire between the shift lever and the ECM. Splice and repair the damaged wire using heat-shrink tubing.

5. 5

   Reassemble and Power Up

   Reconnect the battery and turn the key to the ON position.

6. 6

   Clear the Code

   The cause must be resolved and the error must be cleared using the tractor's in-cab CDU (Customer Diagnostic Unit) or the dealer EST (Electronic Service Tool) by accessing the "H Menu" (Diagnostics Menu).

7. 7

   Test

   Cycle the Power Shuttle FNR lever or clutch pedal to re-enable the transmission, then test drive to ensure the Hi/Lo powershift functions correctly without triggering the code.