Case IH 76 – Transmission ECM (Electronic Control Module) / ECU: NVM_RD_ERR (68 Fixed Mod) - Non-Volatile Memory Read Error

ECM Triplicate Read Error in the Non-Volatile Memory (NVM). The system logs this code when it is impossible to recall any data from the NVM because all three stored memory copies are different or corrupted. The underlying cause is typically a damaged Electrically Erasable Programmable Read Only Memory (EEPROM) micro-chip inside the controller.

• JXC
• Case IH JX Series
• Case IH Farmall series

1. 1

   Verify the Transmission ECM has a solid connection to the battery and is properly grounded to the chassis to rule out voltage spikes or poor grounds.

2. 2

   Attempt to access the tractor's 'H Menu' (Calibration and Diagnostic Unit menu). For Code 76, there will typically be 'No H Menu for diagnostic check' available due to memory corruption.

1. 1

   Disconnect battery

   Disconnect the tractor's negative battery cable to prevent electrical shorts.

2. 2

   Locate ECU

   Locate the Transmission Electronic Control Unit (ECU). On TN/JX series tractors, this is typically located under the right-hand console or dashboard area depending on the cab configuration.

3. 3

   Disconnect wiring

   Disconnect the wiring harness connectors from the faulty ECM.

4. 4

   Remove ECM

   Unbolt and remove the faulty ECM.

5. 5

   Install new ECM

   Install the new Transmission ECM and reconnect the wiring harnesses.

6. 6

   Reconnect battery

   Reconnect the negative battery cable.

7. 7

   Perform first start-up

   Because the new ECM is blank, you must perform the 'First start-up procedure' (Self Configuration) using the tractor's diagnostic interface.

8. 8

   Calibrate clutches

   Access the 'H Menu' and perform the Clutch A and Clutch B calibration procedures so the new ECM can learn the transmission's engagement points.