MBE 900 DDEC VI Troubleshooting – Section 122.1 SPN 3660/FMI 6

Section 122.1
SPN 3660/FMI 6

This diagnosis is typically the Electronic Unit Pump Cylinder #2 Circuit is Shorted to Battery.‪

1. Turn ignition OFF.
2. Disconnect the MCM 120-pin connector.
3. Using the J-48475 Breakout Box and the J-48583 overlay, connect the MCM side of the harness ONLY.
4. Run ignition ON.
5. Measure the voltage between pin 10 of the J-48475 Breakout Box and ground.
   1. If voltage is greater than 0.5v, contact CSC for MCM replacement.
      

      Figure 1. Electronic Unit Pump #2

   2. If voltage is present, repair the short to power between pin 10 of the MCM 120-pin connector and the # 2 Electronic Unit Pump.See Figure "Electronic Unit Pump #2" .