MBE 900 DDEC VI Troubleshooting – Section 131.3 SPN 4226/FMI 3

Section 131.3
SPN 4226/FMI 3

This diagnosis is typically an open circuit.‪

Section 131.3.1
Open Circuit Check

Check as follows:‪

1. Check for multiple codes.
   1. If 51/3 and 4226/3 are present, repair the open between pin 103 of the 120–pin MCM connector and pin 2 of the Inlet Air Delta P Sensor and the Intake Throttle Valve. See Figure "Inlet Air Delta P Sensor" . Refer to "131.3.1.1 Verify Repairs" .
      

      Figure 1. Inlet Air Delta P Sensor

   2. If only 4226/3 is present, go to step 2 .
2. Disconnect the Inlet Air Delta P Sensor.
3. Measure the resistance across pins 1 and 2 of the Inlet Air Delta P Sensor.
   1. If the resistance is greater than 200k Ω, replace the Inlet Air Delta P Sensor.
   2. If the resistance is less than 200k Ω, go to step 4 .
4. Measure the resistance across pins 1 and 3 of the Inlet Air Delta P Sensor.
   1. If the resistance is greater than 50k Ω, replace the Inlet Air Delta P Sensor.
   2. If the resistance is less than 50k Ω, go to step 5 .
5. Turn the ignition ON (key ON, engine OFF).
6. Measure the voltage between pins 1 and 2 of the Inlet Air Delta P Sensor harness connector.
   1. If the voltage is between 4.5 and 5.5 volts, go to step 8 .
   2. If the voltage is less than 4.5 volts, go to step 7 .
7. Measure the voltage between pin 1 of the Inlet Air Delta P Sensor harness connector and ground.
   1. If the voltage is between 4.5 and 5.5 volts, repair the open circuit between pin 2 of the Inlet Air Delta P Sensor harness connector and pin 103 of the 120–pin MCM connector. See Figure "120–pin MCM Connector" . Refer to "131.3.1.1 Verify Repairs" .
   

   Figure 2. 120–pin MCM Connector

   2. If the voltage is less than 4.5 volts, repair the open circuit between pin 1 of the Inlet Air Delta P Sensor harness connector and pin 117 of the 120–pin MCM connector. Refer to "131.3.1.1 Verify Repairs" .
8. Turn the ignition OFF.
9. Disconnect the 120–pin MCM connector.
10. Measure the resistance between pins 1 and 3 of the Inlet Air Delta P Sensor harness connector.
    1. If the resistance is greater than 5 Ω, go to step 11 .
    2. If the resistance is less than 5 Ω, repair the short in wires between pins 1 and 3 of the Inlet Air Delta P Sensor harness connector and pin 109 of the 120–pin MCM connector. Refer to "131.3.1.1 Verify Repairs" .
11. Measure the resistance between pin 3 of the Inlet Air Delta P Sensor harness connector and pin 109 of the 120–pin MCM connector.
    1. If the resistance is greater than 3 Ω, repair the open between pin 3 of the Inlet Air Delta P Sensor harness connector and pin 109 of the 120–pin MCM connector. Refer to "131.3.1.1 Verify Repairs" .
    2. If the resistance is less than 3 Ω, repeat steps 2 through 11 . If the results are the same, contact the Detroit Diesel Customer Support Center (313–592–5800).

Section 131.3.1.1
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.