MBE 4000 DDEC VI Troubleshooting – Section 74.2 SPN 723/FMI 3

Section 74.2
SPN 723/FMI 3

The diagnostic condition is typically an open circuit.‪

Section 74.2.1
Open Circuit Check

Check as follows: ‪

Figure 1. Camshaft Position Sensor

1. Disconnect CMP Sensor
2. Measure the resistance across pins 1 and 2 of the CMP Sensor.See Figure "MCM — Camshaft Position Sensor Schematic" .
   1. If the resistance is between 1000 Ω and 1400 Ω, go to step 3 .
   2. If the resistance is greater than 1400 Ω or less than 1000 Ω, replace the CMP Sensor. Refer to "74.1.1.1 Verify Repairs" .
3. Disconnect the 120–pin MCM connector.
4. Measure the resistance across pins 1 and 2 of the CMP harness connector.
   1. If the resistance is less than 5 Ω, repair short between pins 1 and 2 of the CMP harness connector and the pins 48 and 45 of the MCM 120 pin connector. Refer to "74.1.1.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, go to step 5 .
5. Measure the resistance between pin 1 of the CMP harness connector and pin 48 of the MCM 120 pin connector
   1. If the resistance is greater then 5 Ω, repair open between pin 1 of the CMP harness connector and pin 48 of the MCM 120 pin connector. Refer to "74.1.1.1 Verify Repairs" .
   2. If the resistance is less than 5 Ω, go to step 6 .
6. Measure the resistance between pin 2 of the CMP harness connector and pin 45 of the MCM 120 pin connector.
   1. If the resistance is greater then 5 ohms, repair open between pin 2 of the CMP harness connector and pin 45 of the MCM 120–pin connector. Refer to "74.1.1.1 Verify Repairs" .
   2. If the resistance is less than 5 Ω, review steps 2 through 6 . If the results are the same, contact the Detroit Diesel Customer Support Center (313–592–5800).

Section 74.2.1.1
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.