MBE 900 DDEC VI Troubleshooting – Section 80.1 SPN 1072/FMI 3

Section 80.1
SPN 1072/FMI 3

This diagnosis is typically a short to power.‪

Section 80.1.1
Short to Power Check

Check as follows:‪

1. Disconnect the Constant Throttle Valve connector.
2. Turn the ignition ON (key ON, engine OFF).
3. Measure the voltage between pin 1 of the Constant Throttle Valve connector and ground.
   1. If the voltage is greater than 11.5 volts, repair the short to power between pin 1 of the Constant Throttle Valve connector and pin 32 of the 120–pin MCM connector. See Figure "Constant Throttle Valve" . Refer to "80.1.1.1 Verify Repairs" .
      

      Figure 1. Constant Throttle Valve

   2. If the voltage is less than 11.5 volts, go to step 4 .
4. Turn the ignition OFF.
5. Disconnect the 120–pin MCM connector.
6. Measure the resistance between pins 1 and 2 of the Constant Throttle Valve connector.
   1. If the resistance is greater than 5Ω, repeat steps 2 through 6 . If the results are the same, contact the Detroit Diesel Customer Support Center (313–592–5800).
   2. If the resistance is less than 5Ω, repair the short between pins 1 and 2 of the Constant Throttle Valve and pins 32 and 64 of the 120–pin MCM connector. Refer to "80.1.1.1 Verify Repairs" .

Section 80.1.1.1
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.