MBE 900 DDEC VI Troubleshooting – Section 131.4 SPN 4226/FMI 4

Section 131.4
SPN 4226/FMI 4

This diagnosis is typically a short to ground.‪

Section 131.4.1
Short to Ground Check

Check as follows:‪

1. Disconnect the Inlet Air Delta P Sensor.
2. Disconnect the 120–pin MCM connector.
3. Measure the resistance between pins 1 and 2 of the Inlet Air Delta P Sensor. See Figure "Inlet Air Delta P Sensor" .
   

   Figure 1. Inlet Air Delta P Sensor

   1. If the resistance is less than 5Ω, repair the short between pins 117 and 103 of the 120–pin MCM connector. See Figure "120–pin MCM Connector" . Refer to "131.4.1.1 Verify Repairs" .
   

   Figure 2. 120–pin MCM Connector

   2. If the resistance is greater than 5Ω, go to step 4 .
4. Measure the resistance between pins 2 and 3 of the Inlet Air Delta P Sensor.
   1. If the resistance is less than 5Ω, repair the short between pins 109 and 103 of the 120–pin MCM connector. Refer to "131.4.1.1 Verify Repairs" .
   2. If the resistance is greater than 5Ω, go to step 5 .
5. Measure the resistance between pin 1 of the Inlet Air Delta P Sensor harness connector and ground.
   1. If the resistance is less than 3Ω, repair the short circuit between pin 1 of the Inlet Air Delta P Sensor harness connector and ground. Refer to "131.4.1.1 Verify Repairs" .
   2. If the resistance is greater than 3Ω, go to step 6 .
6. Measure the resistance between pin 3 of the Inlet Air Delta P Sensor harness connector and ground.
   1. If the resistance is less than 3Ω, repair the short circuit between pin 3 of the Inlet Air Delta P Sensor harness connector and ground. Refer to "131.4.1.1 Verify Repairs" .
   2. If the resistance is greater than 3Ω, repeat steps 3 through 6 . If the results are the same, contact the Detroit Diesel Customer Support Center (313–592–5800).

Section 131.4.1.1
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.