Case IH 4354 – TCU: EHR FB 1 Shorted to low source

The system has detected that the sensor feedback voltage for the EHR implement interface dropped below the minimum threshold of 0.25 V.

• Magnum
• Steiger T4B
• Magnum 235
• Magnum 260
• Magnum 290
• Magnum 315
• Magnum 340
• STX Steiger

1. 1

   Verify that the fault is currently present and in an active state

2. 2

   Locate the Tractor Control Unit (TCU) connector C066 and the implement interface (potentiometer) connector C686

3. 3

   Inspect both connectors to ensure they are securely connected, not damaged, the pins are in the correct position, and the fit is tight

1. 1

   Test the Harness

   Use back probes (e.g., SPX/OTC #233788) at the implement interface (potentiometer) connector C686, pin 1.

2. 2

   Measure Voltage

   Turn the ignition switch to the ON position. Measure the voltage between connector C686 pin 1 and a known good ground.

3. 3

   Evaluate Wiring

   If the voltage indicated is less than 0.25 V, the harness has a short to ground or an open circuit. Repair or replace the wiring harness as required.

4. 4

   Software Check

   If the wiring tests good and voltage is within normal operating range (between 0.25 V and 4.5 V), ensure the correct level of software is downloaded to the controller.

5. 5

   Replace Component

   If the harness is intact, the software is correct, and the fault re-occurs, the sensor itself has failed internally. Remove and replace the implement interface (potentiometer).