MBE 4000 DDEC VI Troubleshooting – Section 131.4 SPN 4226/FMI 4

Section 131.4
SPN 4226/FMI 4

This diagnosis is typically Inlet Air Delta P Sensor circuit failed low.‪

Section 131.4.1
Short to Ground Check

Check as follows:‪

1. Check for multiple codes.
   1. If 3563/4, 51/4 and 4226/4 are present, repair the short to ground between pin 117 of the MCM 120–pin connector, the intake throttle valve and the Inlet Air Delta P Sensor. Refer to "131.4.1.1 Verify Repairs" .
   2. If 51/4 and 4226/4 are present, repair the short to ground between pin 117 of the MCM 120–pin connector, the intake throttle valve and the Inlet Air Delta P Sensor. Refer to "131.4.1.1 Verify Repairs" .
   3. If only 4226/4 is present, go to the next step.
2. Turn the ignition OFF.
3. Disconnect the Inlet Air Delta P Sensor.
4. Disconnect the 120–pin MCM connector.
5. Measure the resistance between pin 3 of the Inlet Air Delta P Sensor and ground. See Figure "Inlet Air Delta P Sensor" .
   

   Figure 1. Inlet Air Delta P Sensor

   1. If the resistance is less than 3Ω, repair the short to ground between pin 3 of the Inlet Air Delta P Sensor and 109 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 3Ω, go to step 4 .
6. Measure the resistance between pin 3 of the Inlet Air Delta P Sensor and 109 of the 120–pin MCM connector.
   1. If the resistance is greater than 3Ω, repair the open between pin 3 of the Inlet Air Delta P Sensor and pin 109 of the 120–pin MCM connector. Refer to "131.4.1.1 Verify Repairs" .
   2. If the resistance is less than 3Ω, replace the Inlet Air Delta P Sensor. Refer to "131.4.1.1 Verify Repairs" .

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.