Case IH 56 – Transmission ECM / Controller Guidance System / Transmission Controller (TCU): Power Shuttle FNR Lever Switch Fault / Guidance System Timeout / Backup Alarm Circuit Shorted or Open

Fault Code 56 maps to a Power Shuttle FNR Lever switch fault or a Guidance System timeout. An audible/backup alarm short circuit is officially logged as TRANS Fault Code 148, not 56.

• MX Maxxum
• MX Magnum Series
• TG Series Tractors
• TN Series Tractors
• STX Steiger Series
• STX 325
• STX 500

1. 1

   (For Alarm Short Circuit - Code 148) Access the transmission controller located underneath the fuse/relay panel.

2. 2

   (For Alarm Short Circuit - Code 148) Visually inspect the wiring harness leading to the backup alarm for chafing, bare wires, or disconnected plugs.

3. 3

   (For Alarm Short Circuit - Code 148) Test the backup alarm wiring to determine if it has failed open or is shorted to ground.

4. 4

   (For Fault Code 56 - FNR Lever Switch) Check for faulty wiring between ECM connector 2, pin 20 and the Power Shuttle (PS) FNR Lever Forward Position Switch.

5. 5

   (For Fault Code 56 - FNR Lever Switch) Check for a short across the switch terminals.

6. 6

   (For Fault Code 56 - FNR Lever Switch) Check the circuit between the PS FNR Lever Forward Position Switch and ECM connector 2, pin 26 for an open or short to ground.

1. 1

   Locate controller

   (For Alarm Short Circuit - Code 148) Power down the machine and locate the transmission controller under the fuse/relay panel.

2. 2

   Trace wiring

   (For Alarm Short Circuit - Code 148) Trace the backup alarm circuit wiring from the controller to the audible alarm unit at the rear of the machine.

3. 3

   Repair wiring

   (For Alarm Short Circuit - Code 148) Repair any damaged, pinched, or exposed wiring that is causing a short to ground.

4. 4

   Remove faulty alarm

   (For Alarm Short Circuit - Code 148) If the wiring is intact, the internal circuitry of the backup alarm itself has likely failed (causing excessive current draw). Remove the faulty backup alarm.

5. 5

   Install and test alarm

   (For Alarm Short Circuit - Code 148) Install a replacement backup alarm and test the circuit by placing the machine in reverse (ensure the area is clear) to verify the alarm sounds and the code clears.

6. 6

   Access components

   (For Fault Code 56 - FNR Lever) Access the Power Shuttle FNR lever assembly and the Transmission ECM.

7. 7

   Verify voltage

   (For Fault Code 56 - FNR Lever) Using a multimeter, verify voltage at ECM connector 2, pin 26. If it is below 0.7 volts, proceed to wire repair.

8. 8

   Repair or replace wiring

   (For Fault Code 56 - FNR Lever) Repair or replace the wiring harness if a short or open is found between the ECM and the switch.

9. 9

   Replace switch

   (For Fault Code 56 - FNR Lever) If the wiring tests good, replace the FNR Lever Forward Position Switch, as it has failed internally.