Case IH 19669 – Engine Control Module (ECM / ECU): ECU Powerstage for pre-supply pump: short circuit to battery.

The engine control module has detected a short circuit to a battery voltage source (12V) on the output circuit that powers the electric fuel pre-supply pump (fuel lift pump).

• Tier 4b
• Maxxum series (110, 120, 140)
• Farmall series (110A, 120A)
• JX series (JX70, JX1080U)
• Puma series
• N-Series Tractor Loader Backhoes (TLBs)
• N-Series loaders

1. 1

   Inspect the wiring harness running from the Engine ECU to the electric fuel pre-supply pump for chafed, melted, or pinched wires bridging to a 12V battery source.

2. 2

   Disconnect the electrical connector at the fuel pre-supply pump and check the voltage on the supply pin with the key ON. Constant battery voltage indicates a short in the harness or ECU.

3. 3

   Test the pins on the pre-supply pump itself for an internal short circuit.

4. 4

   Check the fuel pump relay (if equipped) to ensure the contacts are not welded shut, which would provide constant battery voltage to the circuit.

5. 5

   Disconnect the harness at the ECU and check for bent, corroded, or bridged pins.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent electrical damage.

2. 2

   Repair Wiring

   If a short to battery was found in the wiring harness during diagnostics, cut out the damaged section of the wire and splice in a new section using weather-sealed heat-shrink connectors.

3. 3

   Replace the Pre-Supply Pump

   If the pump itself has an internal short: Locate the fuel pre-supply pump, place a drain pan underneath, disconnect the fuel inlet and outlet lines, remove the mounting bolts, and remove the old pump. Install the new pump with a new sealing ring/gasket, and reconnect the fuel lines and the 2-pin electrical connector.

4. 4

   Prime the Fuel System

   Reconnect the battery. Turn the ignition key to the ON position (without starting the engine) for 30 seconds to allow the new electric lift pump to prime the fuel system and purge air.

5. 5

   Clear Codes

   Use a diagnostic scan tool (like the CNH EST) to clear the 19669 fault code from the Engine ECU. Start the engine and verify there are no leaks and the code does not return.