MBE 4000 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 for a short as follows:‪

1. Check for multiple codes.
   1. If 2791/4 and 2791/5 are present, go to step 2 .
   2. If only 2791/4 is present, go to step 5 .
2. Disconnect EGR valve connector.
3. Turn the ignition ON (key ON, engine OFF).
4. Measure the voltage between pin 2 of the EGR valve connector and ground. See Figure "EGR Valve" .
   

   Figure 1. EGR Valve

   1. If the voltage is greater than 11.5 volts, replace the EGR valve.
   2. If the voltage is less than 11.5 volts, repair the open between pin 2 of the EGR valve connector and pin 62 of the MCM 120–pin connector.
5. Turn the ignition OFF.
6. Disconnect 120–pin MCM connector.
7. 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, replace the EGR valve. Refer to "98.2.2.1 Verify Repairs" .

Section 98.2.1.1
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.