Section 62.1
SPN 655/FMI 14

SPN 655/FMI 14 is typically an open circuit, short to ground or short to power.‪

Check as follows:‪

1. Check for multiple codes.
   1. If fault 168/1 is present along with any other faults, service 168/1 first.
   2. If 654/14 and 656/14 are present along with 655/14, go to step 2 .
   3. If only 655/14 is present, go to step 10 .
2. Turn the ignition OFF
3. Disconnect the rear injector harness 14–pin connector.
4. Inspect the rear injector harness 14–pin injector connector for bent or spread pins, inspect the connector seal for damage (signs of water or oil intrusion).
   1. If water or oil intrusion, bent or spread pins are found, repair as necessary. Refer to "62.1.1 Verify Repairs" .
   2. If the connector shows no signs of damage, go to the next step.
5. Measure the resistance between pin 1 and pin 3 on the valve cover side of the injector harness. If using J-48671–10 , measure between injector #5 pins 3 and 4.
   
   1. If the resistance is greater than 3 Ω, replace the under valve cover injector harness. Refer to "62.1.1 Verify Repairs" .
   2. If the resistance is less than 3 Ω, go to the next step.
6. Disconnect the MCM 120-pin connector
7. Measure the resistance between pin 19 of the MCM 120–pin connector and pin 1 of the rear injector harness 14–pin connector.
   
   1. If the resistance is greater then 3 Ω, repair the open between pin 19 of the MCM 120–pin connector and pin 1 of the rear injector harness 14–pin connector. Refer to "62.1.1 Verify Repairs" .
   2. If the resistance is less than 3 Ω, go to the next step.
8. Disconnect the negative battery cable.
9. Measure the resistance between the positive battery post and pin 19 of the MCM 120–pin connector.
   1. If the resistance is less than 3 Ω, repair short to power between battery positive and pin 25 of the MCM 120–pin connector. Refer to "62.1.1 Verify Repairs" .
   2. If the resistance is greater than 3 Ω, contact Detroit Diesel Customer Support Center for MCM replacement authorization.
10. Turn the ignition OFF.
11. Disconnect the rear injector harness 14–pin connector.
12. Measure the resistance between pin 1 and pin 3 on the valve cover side of the injector harness (if using J-48671-10 measure between injector #5 pins 3 and 4).
    1. If the resistance is less than 3 Ω, go to step 18 .
    2. If the resistance is greater than 3 Ω, go to the next step.
13. Remove the upper valve cover.
14. Disconnect injector #5.
15. Measure the resistance between pin 1 of the on the valve cover side of the injector harness and pin 3 of the injector #5 harness connector.
    1. If the resistance is greater than 3 Ω, replace under valve cover injector harness. Refer to "62.1.1 Verify Repairs" .
    2. If the resistance is less than 3 Ω, go to the next step.
16. Measure the resistance between pin 3 of the on the valve cover side of the injector harness and pin 4 of the injector #5 harness connector.
    1. If the resistance is greater than 3 Ω, replace under valve cover injector harness. Refer to "62.1.1 Verify Repairs" .
    2. If the resistance is less than 3 Ω, go to the next step.
17. Measure the resistance between pin 3 of the on the valve cover side of the injector harness and ground.
    1. If the resistance is less than 3 Ω, replace under valve cover injector harness. Refer to "62.1.1 Verify Repairs" .
    2. If the resistance is greater than 3 Ω, replace the injector #5. Refer to "62.1.1 Verify Repairs" .
18. Measure the resistance between pin 3 on the valve cover side of the injector harness and ground (if using J-48671-10 measure between injector #5 pin 4 and ground).
    1. If the resistance is greater than 3 Ω, go to step 22 .
    2. If the resistance is less than 3 Ω, go to the next step.
19. Remove the upper valve cover.
20. Disconnect the injector #5 connector.
21. Measure the resistance between pin 3 on the valve cover side of the injector harness and ground If using J-48671–10 , measure between injector #5 pin 4 and ground.
    1. If the resistance is greater than 3 Ω, replace the injector #5. Refer to "62.1.1 Verify Repairs" .
    2. If the resistance is less than 3 Ω, replace the under valve cover injector harness. Refer to "62.1.1 Verify Repairs" .
22. Disconnect the MCM 120–pin connector.
23. Measure the resistance between pin 3 on the MCM side of the injector harness connector and pin 20 of the MCM 120–pin connector.
    1. If the resistance is greater than 3 Ω, repair open circuit between pin 3 of the injector harness connector and pin 20 of the MCM 120–pin connector. Refer to "62.1.1 Verify Repairs" .
    2. If the resistance is less than 3 Ω, repair short to ground between pin 3 of the injector harness connector and pin 20 of the MCM 120–pin connector. Refer to "62.1.1 Verify Repairs" .

Section 62.1.1
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. If assistance is required, call the Detroit Diesel Customer Support Center at 313–592–5800.