MBE 4000 DDEC VI Troubleshooting – Section 78.2 SPN 975/FMI 4

Section 78.2
SPN 975/FMI 4

This fault indicates that there is a short to ground.‪

Section 78.2.1
Check for Short to Ground

Check for a short to ground as follows:‪

1. Turn the vehicle ignition switch to the OFF position.
2. Disconnect the fan control solenoid.
3. Disconnect the 120–pin MCM connector.
4. Measure the resistance between pin 1 of the fan control solenoid and ground.
   1. If the resistance is less than 5 Ω, repair the short to ground between pin 1 of the fan control solenoid and pin 33 of the 120–pin MCM connector. Refer to "78.2.1.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, repair the short to ground between pin 2 of the fan control solenoid and pin 91 of the 120–pin MCM connector. Refer to "78.2.1.1 Verify Repairs" .

Section 78.2.1.1
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.