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81.1 SPN 1172/FMI 3
This code is typically sensor or circuit failed high.
81.1.1
Open Circuit Check
Check for an open 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.
[a] If the resistance is less than 55 Ω, go to step 7.
[b] If the resistance is greater than 55 Ω, go to step 4.
4. Disconnect the Turbo Compressor In Temperature Sensor (TCI Sensor).
5. Measure the resistance between pin 1 and pin 2 of the TCI Sensor.
[a] If the resistance is greater than 50 Ω, replace the sensor. Refer to section 81.1.2.1.
[b] 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.
[a] 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 section 81.1.2.1.
[b] 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 section 81.1.2.1.
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.
[a] If the voltage is less than 4.5 volts, go to step 9.
[b] If the voltage is greater than 4.5 volts, refer to section 81.1.2.
9. Measure the voltage between pin 27 of the 31–pin connector and ground.
[a] 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 section 81.1.2.1.
[b] 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 section
81.1.2.1.
81.1.2
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.
All information subject to change without notice.
6SE568
Copyright © PRELIMINARY 2007 DETROIT DIESEL CORPORATION
(Rev. )
MBE 4000 DDEC VI TROUBLESHOOTING GUIDE
81-3
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Table of Contents
Troubleshooting
