MBE 900 DDEC VI Troubleshooting – Section 98.2 SPN 2791/FMI 4

Section 98.2
SPN 2791/FMI 4

This diagnosis is typically short to ground.‪

Section 98.2.1
Short Circuit Check

Check as follows:‪

1. Disconnect EGR valve connector. See Figure "EGR Valve" .
   

   Figure 1. EGR Valve

2. Disconnect 120–pin MCM connector.
3. Measure the resistance between pin 1 of the EGR valve connector and ground.
   1. If the resistance is less than 5 Ω, repair the short circuit between pin 1 of the EGR valve connector and ground. Refer to "98.2.2.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, go to step 4 .
4. Measure the resistance between pin 2 of the EGR valve connector and ground.
   1. If the resistance is less than 5 Ω, repair the short circuit between pin 2 of the EGR valve connector and ground. Refer to "98.2.2.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, Refer to "98.2.2.1 Verify Repairs" .

Section 98.2.2
Resistance and Voltage Check

The resistance and voltage check performed indicate that you should not be getting a code. The following is a recheck before requesting a new MCM.‪

1. Reconnect all connectors.
2. Turn the vehicle ignition ON (key ON, engine OFF), and clear codes.
3. Disconnect EGR valve connector.
4. Disconnect 120–pin MCM connector.
5. Measure the resistance between pin 1 of the EGR valve connector and ground.
   1. If the resistance is less than 5 Ω, repair the short circuit between pin 1 of the EGR valve connector and ground. Refer to "98.2.2.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, go to step 6 .
6. Measure the resistance between pin 2 of the EGR valve connector and ground.
   1. If the resistance is less than 5 Ω, repair the short circuit between pin 2 of the EGR valve connector and ground. Refer to "98.2.2.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, call the Detroit Diesel Customer Support Center (313–592–5800) for authorization to replace the MCM.

Section 98.2.2.1
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.