Skip to main content


To determine if a faulty electronic control module (ECM) is causing the cylinder to misfire, perform the following: ‪

  1. Remove the ECM connector hold-down screws securing the five or six wire harness connection.

    Note: Carefully disengage the lock tab on the power harness and injector harness connectors when removing.

  2. Remove the thru-bolts holding the ECM to the engine; refer to Section .
  3. Remove the ECM from the engine and tag the ECM for core return.
  4. Obtain a new reprogrammed ECM for the engine being troubleshooted.
  5. Inspect the ECM isolators for any damage, refer to Section . Replace if necessary, refer to Section .
  6. Install the ECM to the engine using thru-bolts; refer to Section .
  7. Torque the ECM thru-bolts to 23-27 Nm (17-20 lbft).
  8. Torque the ECM connector hold-down screws to 24-30 Nm (21-26 lb in.).
  9. Verify ECM repair, refer to Section .

Faulty ECM Repair

Return tagged cores to designated repair facilities. Contact Detroit Diesel Technical Service Group. Refer to Section for verification of ECM replacement. ‪

Verification of Repair for Faulty ECM

Perform the following to determine if the new ECM resolved the misfiring cylinder condition: ‪

  1. Start the engine.
  2. Run the engine speed up to the occurrence of the misfiring.
  3. Listen for misfiring cylinder.
    1. If the engine is not misfiring, shut down the engine. No further troubleshooting is required.
    2. If the engine is misfiring, shut down the engine and check for worn or damaged valves and cylinder kits; refer to Section .