MBE 900 DDEC VI Troubleshooting – Section 34.2 SPN 174/FMI 4

Section 34.2
SPN 174/FMI 4

SPN 174/FMI 4 indicates a SFT Sensor short to ground.‪

Section 34.2.1
Short to Ground Check

Check as follows:‪

1. Disconnect the SFT Sensor.
2. Disconnect the 120-pin MCM connector.
3. Measure the resistance across pins 1 and 2 of the SFT Sensor connector.
   1. If resistance is less than 5 Ω, repair short between wires 55 and 77 of the 120-pin MCM connector. Refer to "34.2.1.1 Verify Repairs" .
   2. If resistance is greater than 5 Ω, go to step 4 .
4. Measure the resistance between pin 1 of the SFT Sensor harness connector and ground. See Figure "Supply Fuel Temperature Sensor" .
   

   Figure 1. Supply Fuel Temperature Sensor

   1. If resistance is less than 5 Ω, repair the short circuit between pin 1 of the SFT Sensor harness connector and ground. Refer to "34.2.1.1 Verify Repairs" .
   2. If resistance is greater than 5 Ω, go to step 5 .
5. Measure the resistance between pin 2 of the SFT Sensor harness connector and ground.
   1. If resistance is less than 5 Ω, repair the short circuit between pin 2 of the SFT Sensor harness connector and ground. Refer to "34.2.1.1 Verify Repairs" .
   2. If resistance is greater than 5 Ω, review steps 3 through 5 . If the results are the same, contact Detroit Diesel Customer Support Center (313–592–5800).

Section 34.2.1.1
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.
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.