DD15 SPN 2791/FMI 11 Troubleshooting - Detroit Diesel Troubleshooting Diagrams (2025)

SPN 2791/FMI 11

The fault description is the EGR Actuator (Failsafe Mode, Motor On).‪

Check as follows:‪

1. Using DDDL 7.X, check SPN 2791/FMI 11 Extended Data Record #3 “Physical Data” for the Reserved Extreme Parameter value as seen in the following DDDL screen.

2. The action to take is listed in the following table.
   

   Reserved Extreme Parameter‪	Action to Take‪
   3, 4, 9, 10, 22, 23, 65535‪	Go to step 3.‪
   15, 255‪	Go to step 7.‪
   8, 11‪	Go to step 11.‪
   5, 7, 20‪	Replace EGR Actuator.‪

3. Turn the ignition OFF.
4. Physically move EGR Actuator rod from stop to stop to check for unrestricted movement.
   1. If unrestricted movement is felt,go to step 7.
   2. If actuator rod does not freely move from stop to stop, go to the next step.
5. Disconnect the EGR Actuator rod arm. Inspect the ball sockets on arm for free movement.
   1. If the sockets do not rotate/move freely, replace the EGR Actuator rod arm.Refer to “97.7.1 Verify Repairs”.
   2. If the sockets move freely, go to the next step.
6. Physically move the EGR butterfly valve from stop to stop to check for unrestricted movement.
   1. If the EGR butterfly valve does not move stop to stop, replace the EGR butterfly valve. Verify repairs.
   2. If EGR butterfly valve moves stop to stop, replace the EGR Actuator.Refer to “97.7.1 Verify Repairs”.
7. Disconnect EGR Actuator harness connector.
8. Turn the ignition ON (key ON, engine OFF).
9. Measure the voltage between pins 1 and 2 of the EGR Control Actuator connector.
   1. If the voltage is greater than 11 volts,go to step 11.
   2. If the voltage is less than 11 volts, go to the next step.
10. Measure the voltage between pin 1 of the EGR Control Actuator connector and ground.
    1. If the voltage is less than 11 volts, repair wire between pin 1 of the EGR Control Actuator connector and pin 62 of the MCM 120–pin connector.Refer to “97.7.1 Verify Repairs”.
    2. If the voltage is greater than 11 volts, repair wire between pin 2 of the EGR Control Actuator connector and pin 67 of the MCM 120–pin connector.Refer to “97.7.1 Verify Repairs”.
11. Turn the ignition OFF.
12. Disconnect the EGR Actuator.
13. Measure the resistance between pins 3 and 4 on the engine harness side of the EGR Control Actuator connector.
    1. If the resistance is between 55 and 65 Ω, replace the EGR Actuator.Refer to “97.7.1 Verify Repairs”.
    2. If the resistance is not between 55 and 65 Ω, go to the next step.
14. Disconnect the MCM 120–pin connector.
15. Measure the resistance between pins 3 and 4 of the EGR Control Actuator connector.
    1. If the resistance is less than 3 Ω, repair short between pins 3 and 4 of the EGR Control Actuator connector and MCM pins 74/75.Refer to “97.7.1 Verify Repairs”.
    2. If the resistance is greater than 3 Ω, go to the next step.
16. Measure the resistance between pin 3 of the EGR Control Actuator connector and pin 74 of the MCM 120–pin connector.
    1. If the resistance is greater than 3 Ω, repair wire between pin 3 of the EGR Control Actuator connector and pin 74 of the MCM 120–pin connector.Refer to “97.7.1 Verify Repairs”.
    2. If the resistance is less than 3 Ω, go to the next step.
17. Measure the resistance between pin 4 of the EGR Control Actuator connector and pin 75 of the MCM 120-pin connector.
    1. If the resistance is greater than 3 Ω, repair wire between pin 4 of the EGR Control Actuator connector and pin 75 of the MCM 120–pin connector.Refer to “97.7.1 Verify Repairs”.
    2. If the resistance is less than 3 Ω, replace the MCM.

Verify Repairs

Verify repairs as follows:‪

1. Turn ignition OFF.
2. Reconnect any electrical connections that were disconnected to perform the diagnosis.
3. Clear codes with DDDL 7.0 or latest version.
   

   ENGINE EXHAUST‪
   To avoid injury from inhaling engine exhaust, always operate the engine in a well-ventilated area. Engine exhaust is toxic.‪

4. Start and bring engine up to operating temperature (over 140°F/60°C).
5. Verify operation is satisfactory and no warning lamps illuminate. If warning lamps illuminate, troubleshoot the codes.