MBE 4000 DDEC VI Troubleshooting – Section 74.1 SPN 723/FMI 1

Section 74.1
SPN 723/FMI 1

The diagnostic condition is typically low voltage.‪

Section 74.1.1
Low Voltage Check

Check as follows:‪

1. Disconnect the MCM 120–pin connector.
2. Measure the resistance between pins 45 and 48 of the MCM 120–pin connector.
   1. If the resistance is greater than 1400 Ω, replace the CMP Sensor. Refer to "74.1.1.1 Verify Repairs" .
   2. If the resistance is less than 1400 Ω, repair the short to ground between pin 2 of the CMP Sensor harness connector and pin 45 of the MCM 120–pin connector. Refer to "74.1.1.1 Verify Repairs" .

Section 74.1.1.1
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.