MBE 900 DDEC VI Troubleshooting – Section 82.2 SPN 1172/FMI 3

Section 82.2
SPN 1172/FMI 3

This code is typically sensor or circuit failed high.‪

Section 82.2.1
Open Circuit Check

Check as follows:‪

1. Turn the ignition OFF.
2. Disconnect the 31–pin connector.
3. Measure the resistance between pin 27 and pin 28 of the 31–pin connector on the truck side.
   1. If the resistance is less than 55 Ω, go to step 7 .
   2. If the resistance is greater than 55 Ω, go to step 4 .
4. Disconnect the Turbo Compressor In Temperature Sensor (TCI Sensor). See Figure "Turbo Compressor In Temperature Sensor" .
   

   Figure 1. Turbo Compressor In Temperature Sensor

5. Measure the resistance between pin 1 and pin 2 of the TCI Sensor.
   1. If the resistance is greater than 50 Ω, replace the sensor. Refer to "82.2.2.1 Verify Repairs" .
   2. If the resistance is less than 50 Ω, go to step 6 .
6. Measure the resistance between pin 1 of the TCI Sensor connector and pin 27 of the 31–pin connector.
   1. If the resistance is greater than 3 Ω, repair the open between pin 1 of the TCI Sensor connector and pin 27 of the 31–pin connector. Refer to "82.2.2.1 Verify Repairs" .
   2. If the resistance is less than 3 Ω, repair the open between pin 2 of the TCI Sensor connector and pin 28 of the 31–pin connector. Refer to "82.2.2.1 Verify Repairs" .
7. Turn the ignition ON (key ON, engine OFF).
8. Measure the voltage between pin 27 and pin 28 of the 31–pin connector on the engine side.
   1. If the voltage is less than 4.5 volts, go to step 9 .
   2. If the voltage is greater than 4.5 volts, refer to "82.2.2 Resistance and Voltage Check" .
9. Measure the voltage between pin 27 of the 31–pin connector and ground.
   1. If the voltage is less than 4.5 volts, repair the open between pin 27 of the 31–pin connector and pin 86 of the 120–pin MCM connector. Refer to "82.2.2.1 Verify Repairs" .
   2. If the voltage is between 4.5 volts and 5.5 volts, repair the open between pin 28 of the 31–pin connector and pin 114 of the 120–pin MCM connector. Refer to "82.2.2.1 Verify Repairs" .

Section 82.2.2
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 vehicle ignition OFF. Reconnect all connectors.
2. Turn ignition ON. Clear codes with diagnostic tool.
3. Measure the voltage between pin 27 and pin 28 of the 31–pin connector on the engine side.
   1. If the voltage is less than 4.5 volts, refer to "82.2.1 Open Circuit Check" , step 9 .
   2. If the voltage is greater than 4.5 volts, contact the Detroit Diesel Customer Support Center (313–592–5800) for authorization to replace the MCM.

Section 82.2.2.1
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.