Case IH 19668 – Engine Control Unit (ECU): ECU Powerstage for pre-supply pump: Over temperature error

The ECU powerstage (internal driver circuit) for the pre-supply pump is overheating. This is almost always caused by the pre-supply pump drawing excessive electrical current due to an internal motor failure, a short in the wiring harness, or a severe fuel restriction forcing the pump to overwork.

• Tier 4b
• 580N
• 580SN (Super N)
• 580SN WT
• 590SN

1. 1

   Perform a current draw test on the pre-supply pump using a fused jumper wire and multimeter. If amperage exceeds OEM specs, the pump motor is failing and causing the ECU driver to overheat.

2. 2

   Trace the wiring harness from the pre-supply pump back to the ECU. Look for chafed wires, melted insulation, or a short-to-ground that could cause high current draw.

3. 3

   Disconnect the ECU harness and inspect the pins for the pre-supply pump circuit for signs of melting, burning, or corrosion caused by excessive heat.

4. 4

   Check the primary fuel filters and fuel lines from the tank to the pump for clogs or pinches that could cause the pump to dead-head or strain.

1. 1

   Safety First

   Turn off the machine, remove the key, and disconnect the negative battery cable to protect the ECU from further electrical spikes.

2. 2

   Relieve Pressure

   Clean the area around the fuel pre-supply pump to prevent debris from entering the fuel system. Place a catch pan underneath.

3. 3

   Disconnect Lines & Wiring

   Unplug the electrical connector from the pump. Disconnect the fuel inlet and outlet lines. Cap the lines to prevent excessive fuel drainage.

4. 4

   Remove the Pump

   Remove the mounting bolts (typically a 2-hole mounting flange) securing the pump to the engine block or mounting bracket.

5. 5

   Install the New Pump

   Clean the mounting surface. Install the new pre-supply pump using a new O-ring/gasket. Tighten the mounting bolts to OEM torque specs.

6. 6

   Reconnect

   Reattach the fuel lines and plug in the electrical connector.

7. 7

   Prime the System

   Use the manual priming lever located on the new transfer pump to bleed air from the fuel lines until you feel firm resistance.

8. 8

   Test

   Reconnect the battery. Turn the key to the ON position to allow the ECU to cycle the pump. Clear the 19668 fault code using a diagnostic scan tool. Start the engine and check for fuel leaks and verify the code does not return.