Case IH 3811 (F-3509-12) - ECU – Engine Control Unit (ECU) / EDC: ECU 5 volt sensor supply 1 out of range failure

The Engine Control Unit (ECU) has detected that its internal regulated 5-volt reference circuit #1—which powers various engine sensors—is operating outside of its expected voltage range. The voltage is either too high (shorted to a high source/battery), too low (shorted to ground), or the ECU has suffered an internal hardware failure.

• VESTRUM CVX
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• SR175
• TR series
• Tractors
• Magnum
• Steiger
• Farmall
• MX/TG series
• Combines
• 240 Series Axial-Flow

1. 1

   Verify that the machine's base battery voltage is within the normal operating range, as extreme over-voltage can cause ECU supply faults.

2. 2

   Inspect the engine wiring harness and connectors for chafing, melting, or water intrusion, paying special attention to the 60-pin connector at the Engine ECU.

3. 3

   Check the specific pins for Sensor Supply 1 (typically pins A07, A08, A09, A10, A11, A12, and A13 on standard Case IH 60-pin engine connectors).

4. 4

   Disconnect the sensors on this 5V loop one by one while monitoring the voltage to see if the 5V reference returns to normal, as a dead short in one sensor can trigger this code.

1. 1

   Power Down

   Turn the key switch to the OFF position.

2. 2

   Inspect Connectors

   Disconnect the ECU harness and verify all connectors to the ECU are not damaged, bent, or corroded. Verify the connector locks are not broken and securely hold the connectors in place.

3. 3

   Test the Harness

   With the ECU disconnected, use a multimeter to check the 5-volt supply wires in the harness for continuity to ground or a short to battery voltage. If damaged wiring is found: Repair or replace the damaged engine wiring harness section and retest the circuit.

4. 4

   Test the Sensors

   If the harness is intact, disconnect all sensors on the Supply 1 circuit. Turn the key ON and measure the voltage output directly at the ECU pins. If the voltage is exactly 5V: One of the sensors is internally shorted. Reconnect them one by one until the voltage drops/spikes, identifying the faulty sensor. Replace the faulty sensor.

5. 5

   Replace the ECU

   If the harness is good, all sensors are disconnected, and the ECU is still failing to output a regulated 5 volts (or is outputting battery voltage), the ECU has suffered an internal failure. The Engine Control Module must be replaced and reprogrammed by a dealer.

6. 6

   Clear Codes

   Use an Electronic Service Tool (EST) to clear the inactive fault codes and run the engine to verify the repair.