Deutz-Fahr 657 – EMR3: Short Circuit in Injector 7

A short circuit has been detected in the circuit associated with injector 7. The engine control unit (ECU) detects this fault when the current or voltage level in the injector's circuit falls outside its expected range, indicating an electrical malfunction in the wiring, connector, or the injector's solenoid coil itself. This condition can lead to engine misfires, shaking, loss of power, or engine shutdown if the number of active cylinders falls below a minimum threshold.

1. 1

   Visually inspect the wiring harness for injector 7 from the ECU to the injector for signs of damage, chafing, melting, corrosion, or loose connections

2. 2

   Disconnect and inspect the electrical connectors at injector 7 and the ECU for bent, spread, or pushed-back terminals, as well as oil or dirt contamination

3. 3

   Use a multimeter to check the injector control wire for a short to ground (FMI 4) by testing continuity to chassis ground (should be open circuit)

4. 4

   Check the injector control wire for a short to power (FMI 3) by testing for voltage with the ignition on and engine off (should be zero voltage)

5. 5

   Check for an open circuit (FMI 5) by testing continuity of the injector control and power supply wires from the ECU connector to the injector connector

6. 6

   Test the injector solenoid by measuring resistance between its two terminals (expected range is 0.5 to 2.0 ohms; near-zero indicates an internal short, infinite indicates a broken coil)

7. 7

   Perform a cylinder balance test using a diagnostic scan tool (e.g., Deutz SerDia) to see if deactivating the injector causes an RPM drop

1. 1

   Repair wiring harness

   If a short circuit or break is found during multimeter testing, repair or replace the damaged section of the wiring harness. Ensure all connections are secure and properly insulated.

2. 2

   Replace fuel injector

   If the injector solenoid fails the resistance test (internally shorted or open), replace the injector. Park the machine on a level surface and ensure it cannot move. Clean the area, disconnect the negative battery terminal, disconnect the electrical connector, and remove fuel lines (cap immediately). Remove the hold-down bolt or clamp. Carefully remove the injector (a specialized removal tool or slide hammer may be necessary if stuck). Ensure the injector bore in the cylinder head is clean and free of debris. Install the new injector with a new seal ring, install the hold-down clamp and torque to manufacturer specifications, reconnect lines and connector, reconnect the battery, and bleed the fuel system.

3. 3

   Clear fault codes

   Start the engine and check for fuel leaks. Use a diagnostic tool to clear the fault code from the ECU and verify that it does not return.