MBE 4000 DDEC VI Troubleshooting – Section 28.3 SPN 103/FMI 3

Section 28.3
SPN 103/FMI 3

This diagnosis is typically circuit failed high (open circuit).‪

Section 28.3.1
Open Circuit Check

Check for an open as follows:‪

1. Disconnect the Turbo Speed Sensor (TSS).
2. Measure the resistance across pins 1 and 2 of the sensor (see Figure "Turbo Speed Sensor Terminal and Wire Locations" ).
   1. If the resistance is greater than 1k Ω, replace the sensor. Refer to "28.3.2.1 Verify Repairs" .
   2. If the resistance is less than 1k Ω, go to step 3 .
3. Turn the ignition switch to the ON position.
4. Measure the voltage between pins 1 and 2 of the TSS harness connector.
   1. If the voltage is between 4.5 and 5.5 volts, refer to "28.3.2 Resistance and Voltage Check" .
   2. If the voltage is less than 4.5 volts, go to step 5 .
5. Measure the voltage between pin 2 of the TSS harness connector and ground.
   1. If the voltage is between 4.5 and 5.5 volts, repair the open circuit between pin 1 of the TSS harness connector and pin 50 of the 120–pin MCM connector. See Figure "Turbo Speed Sensor Terminal and Wire Locations" . Refer to "28.3.2.1 Verify Repairs" .
   2. If the voltage is less than 4.5 volts, repair the open circuit between pin 2 of the TSS harness connector and pin 51 of the 120–pin MCM connector. See Figure "Turbo Speed Sensor Terminal and Wire Locations" . Refer to "28.3.2.1 Verify Repairs" .

Figure 1. Turbo Speed Sensor Terminal and Wire Locations

Section 28.3.2
Resistance and Voltage Check

The resistance and voltage check performed indicate that you should not be getting a code. The following is a recheck before requesting a new MCM.‪

1. Turn the ignition OFF.
2. Reconnect the TSS.
3. Clear codes. Run engine for one minute. Stop engine.
4. Recheck codes.
   1. If there are no codes, troubleshooting is finished.
   2. If code 103/ 3 is logged, go to step 5 .
5. Disconnect the Turbo Speed Sensor (TSS).
6. Measure the resistance across pins 1 and 2 of the sensor.
   1. If the resistance is greater than 1.1k Ω, replace the sensor. Refer to "28.3.2.1 Verify Repairs" .
   2. If the resistance is less than 1.1k Ω, go to step 7 .
7. Turn the ignition switch to the ON position.
8. Measure the voltage between pins 1 and 2 of the TSS harness connector.
   1. If the voltage is between 4.5 and 5.5 volts, contact the Detroit Diesel Customer Support Center (313–592–5800) for authorization to replace the MCM.
   2. If the voltage is less than 4.5 volts, refer to "28.3.1 Open Circuit Check" , step 5 .

Section 28.3.2.1
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.