Case IH 19670 – Engine Control Module (ECM): ECU Powerstage for pre-supply pump: short circuit to ground

The Engine Control Module (ECM) has detected that the output driver circuit (powerstage) responsible for supplying voltage to the electric fuel pre-supply pump (lift pump) is shorted directly to ground. The ECM shuts down the circuit to protect itself, preventing the pre-supply pump from running, which typically results in fuel starvation, a loss of fuel rail pressure, and a crank-no-start or engine stalling condition.

• Tier 4b
• Case N-Series loader backhoes
• Case tractors
• CNH Industrial equipment with FPT Tier 4 Final engines

1. 1

   Visual Inspection: Inspect the wiring harness running from the ECM to the electric pre-supply pump. Look for chafed insulation, pinched wires, or areas where the harness is rubbing against the engine block or chassis.

2. 2

   Disconnect and Test (Code Change Method): Disconnect the electrical connector at the pre-supply pump. Turn the ignition key to the ON position and check the active fault codes. If the code changes from 19670 (Short to Ground) to 19667 (Open Load), the wiring is fine, and the short circuit is internal to the pre-supply pump. If code 19670 remains active while the pump is unplugged, the short to ground is located in the wiring harness between the pump connector and the ECM.

3. 3

   Harness Continuity Test: With the battery disconnected and the ECM unplugged, use a multimeter to check for continuity between the pump's power supply wire and a known good chassis ground. If continuity exists, trace the wire to find the short.

4. 4

   Pump Resistance Test: Measure the resistance across the terminals of the pre-supply pump, and from the power terminal to the pump housing. A reading of near zero ohms to the housing indicates an internal short.

1. 1

   Turn off the machine and disconnect the negative battery cable.

   If the fault is in the wiring harness: Turn off the machine and disconnect the negative battery cable.

2. 2

   Trace the power supply wire from the pre-supply pump back to the ECM.

   Trace the power supply wire from the pre-supply pump back to the ECM.

3. 3

   Locate the chafed or melted section of the wire.

   Locate the chafed or melted section of the wire.

4. 4

   Cut out the damaged section and splice in a new piece of wire using weather-sealed heat-shrink butt connectors.

   Cut out the damaged section and splice in a new piece of wire using weather-sealed heat-shrink butt connectors.

5. 5

   Wrap the repaired section in protective wire loom and secure it away from vibration points or heat sources using zip ties.

   Wrap the repaired section in protective wire loom and secure it away from vibration points or heat sources using zip ties.

6. 6

   Turn off the machine and disconnect the negative battery cable.

   If the fault is internal to the pre-supply pump: Turn off the machine and disconnect the negative battery cable.

7. 7

   Clean the area around the pre-supply pump to prevent dirt from entering the fuel system.

   Clean the area around the pre-supply pump to prevent dirt from entering the fuel system.

8. 8

   Disconnect the electrical connector from the pump.

   Disconnect the electrical connector from the pump.

9. 9

   Clamp the fuel lines leading to and from the pump to prevent excessive fuel spillage.

   Clamp the fuel lines leading to and from the pump to prevent excessive fuel spillage.

10. 10

    Remove the fuel lines from the pump (have a catch pan ready for residual fuel).

    Remove the fuel lines from the pump (have a catch pan ready for residual fuel).

11. 11

    Unbolt the pump from its mounting bracket and remove it.

    Unbolt the pump from its mounting bracket and remove it.

12. 12

    Install the new pre-supply pump and tighten the mounting bolts.

    Install the new pre-supply pump and tighten the mounting bolts.

13. 13

    Reconnect the fuel lines and the electrical connector.

    Reconnect the fuel lines and the electrical connector.

14. 14

    Reconnect the battery.

    Reconnect the battery.

15. 15

    Turn the key to the ON position (without cranking) several times to allow the new pump to prime and bleed air from the low-pressure fuel system.

    Turn the key to the ON position (without cranking) several times to allow the new pump to prime and bleed air from the low-pressure fuel system.

16. 16

    Clear the fault codes using a diagnostic scan tool and start the engine to verify the repair.

    Clear the fault codes using a diagnostic scan tool and start the engine to verify the repair.