MBE 4000 DDEC VI Troubleshooting – Section 125.1 SPN 3663/FMI 6

Section 125.1
SPN 3663/FMI 6

This diagnosis is typically the Electronic Unit Pump Cylinder #5, Circuit Shorted to Battery.‪

Section 125.1.1
Circuit Shorted to Battery

Check as follows:‪

1. Turn the ignition OFF.
2. Disconnect the MCM 120 pin connector.
3. Using the J-48475 breakout box and J-48583 overlay connect the MCM side of the harness ONLY.
4. Turn the ignition ON.
5. Measure the voltage between pin 8 of the J-48475 breakout box and ground.
   1. If voltage is greater than 0.5v, contact the Detroit Diesel Customer Support Center at 313–592–5800 for MCM replacement.
      

      Figure 1. Electronic Unit Pump #5

   2. If no voltage is present, repair short to power between pin 8 of the MCM 120 pin connector and the #5 Electronic Unit Pump. See Figure "Electronic Unit Pump #5" .