Case IH 3735 – Engine Control Unit (ECU) / EDC: Fuel Metering Unit Circuit. - Over Temperature Of Device Driver Of Metering Unit

The internal device driver inside the engine controller (which supplies the PWM signal to the metering unit) overheats. This is almost always caused by excessive current draw, typically stemming from a short circuit in the wiring harness or an internally shorted coil inside the Fuel Metering Unit itself.

• Farmall
• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• SR175
• Steiger series tractors
• Puma series tractors
• 240 Series Axial-Flow Combines

1. 1

   Use the Electronic Service Tool (EST) to verify if the code is active and look for accompanying codes like 3911 (Short Circuit to Battery) or 3912 (Short Circuit to Ground) which point directly to wiring faults.

2. 2

   Inspect the engine wiring harness between the ECU and the Fuel Metering Unit for chafed insulation, melted wires, or pinched harnesses.

3. 3

   Disconnect the Fuel Metering Unit and measure the resistance across its pins to check for an internally shorted solenoid coil.

4. 4

   Check the ECU connector pins for signs of arcing, melting, or corrosion caused by high current.

1. 1

   Disconnect battery power

   Disconnect the machine's battery power before servicing the ECU or high-pressure fuel system wiring.

2. 2

   Repair or replace wiring harness

   If the wiring harness is damaged or shorted, repair the affected section or replace the engine wiring harness.

3. 3

   Replace Fuel Metering Unit

   If the Fuel Metering Unit fails the resistance test (shorted coil), remove it from the high-pressure fuel pump and install a new unit.

4. 4

   Reconnect and clear codes

   Reconnect all components, restore battery power, and clear the fault codes using the EST.

5. 5

   Test engine operation

   Run the engine. If fault code 3735 returns and the wiring and metering unit are confirmed to be in good working order, the ECU's internal driver has suffered permanent hardware damage from the overheating event.

6. 6

   Replace Engine Controller

   Reprogram/Replace EDC - Replace Engine Controller If Fault Persists. If EDC Replaced, Follow The Appropriate Service Tool Procedure To Restore Self Learning Parameters.