Case IH 62 – Transmission Control Unit (TCU): HI_LO_SYNCRO_SW_LO_ERR 77' Fixed Lim

The transmission controller has detected an open circuit or a short-to-ground on the low signal circuit of the Hi-Lo synchronizer switch (pushbutton), resulting in a 'Fixed Limit' state.

• JXC
• Farmall 90C
• Farmall 100C
• Farmall 105C
• Farmall 110C
• Farmall 115C
• Farmall 120C
• JXU
• TN55
• TN60A
• TN65
• TN70A
• TN75A
• TN85A
• TN95A

1. 1

   Turn the starter key to the OFF position

2. 2

   Remove the rear left-hand wheel and the solenoid valves unit guard to access the transmission switches

3. 3

   Locate the Hi-Lo synchronizer switch and inspect wiring connection (105). Check if the plug is simply disconnected

4. 4

   Check for electrical continuity between connection (105) on the switch and pin (A3) on connection (177) to verify the wiring harness is intact

5. 5

   Test the wire on connection (105) with a multimeter to see if it is shorted to ground

1. 1

   Turn the ignition off, remove the key, and ensure the tractor is safely parked and chocked.

2. 2

   Remove the rear left-hand wheel to gain access to the transmission's lateral gear unit body.

3. 3

   Unbolt and remove the solenoid valves unit guard.

4. 4

   Locate the Hi-Lo synchronizer switch and its wiring connector (105).

5. 5

   If the connector is loose, reconnect it securely.

6. 6

   If your diagnostic checks revealed an open circuit or a short to ground in the harness, repair or splice the affected section of the wiring.

7. 7

   If the wiring tests good but the switch itself fails internal continuity checks, unscrew the faulty Hi-Lo synchronizer switch and install a replacement.

8. 8

   Reinstall the solenoid valves unit guard and torque the rear left-hand wheel bolts to spec.

9. 9

   The cause must be resolved and the error must be cleared using the tractor's CDU (Control Display Unit) or the EST (Electronic Service Tool) via the HF Menu.