Case IH 1746-02 - IMM – IMM / ICU: LF initiator communication error

Communication between the ignition key and the ICU (Immobilizer Control Unit) has been disturbed. The control unit cannot read the key's transponder, preventing the machine from starting.

• MAGNUM AFS Connect
• Maxxum series (5120, 5130, 5140, 5150, 5220, 5230, 5240, 5250)
• Magnum series (200, 220, 310)
• Steiger/Quadtrac/Rowtrac series
• Legacy series (55, 56, 85, 43, 44 series)

1. 1

   Test the system using a spare key (e.g., the red master key or a secondary blue key) to rule out a dead or damaged transponder chip inside the primary key.

2. 2

   Check the wiring harness and connection cable between the LF initiator (antenna unit) and the Immobilizer Control Unit for damage, high resistance, or disconnected pins.

3. 3

   Check battery voltage and alternator output, as low voltage or cold start voltage drops can trigger communication errors between the key and the ICU.

4. 4

   Check the supply module if the 1746 error persists frequently alongside CAN sensing errors.

1. 1

   Inspect wiring harness

   Inspect the wiring harness connecting the ignition switch's antenna unit to the ICU. Repair any broken wires or loose connectors.

2. 2

   Test with backup key

   If the wiring is intact, attempt to start the machine with a backup key. If the backup key works, the original key's transponder has failed and the key must be replaced.

3. 3

   Replace defective components

   If the error persists with all keys and the wiring is verified good, the LF initiator (antenna) or the Immobilizer Control Unit is defective and must be replaced.

4. 4

   Program new keys

   If installing a new immobilizer kit, you must use the provided red master key to teach/program the new blue mechanical keys to the system according to the manufacturer's assembly instructions.

5. 5

   Clear fault codes

   Clear the fault codes using a diagnostic tester and cycle the ignition to verify the repair.