Detroit Diesel MBE 4000 DDEC VI Troubleshooting Manual page 583

81.2 SPN 1172/FMI 4
This code is typically sensor or circuit failed low.
81.2.1 Short Circuit Check
Check for short as follows:
1. turn the ignition OFF.
2. Disconnect the 31–pin connector.
3. Disconnect the TCI Sensor.
4. Measure resistance between pin 27 and pin 28 of the 31–pin connector on the vehicle side.
[a] If the resistance is less than 10 Ω, repair the short between pin 27 and pin 28 of the
31–pin connector. Refer to section 81.2.1.1.
[b] If the resistance is greater than 10 Ω, go to step 5.
5. Measure resistance between pin 27 of the 31–pin connector and ground on the vehicle side.
[a] If the resistance is less than 5 Ω, repair the short to ground between pin 27 of the
31–pin connector and pin 1 of the TCI Sensor. Refer to section 81.2.1.1.
[b] If the resistance is greater than 5 Ω, go to step 6.
6. Measure resistance between pin 28 and ground on the vehicle side.
[a] If the resistance is less than 5 Ω, repair the short to ground between pin 28 of the
31–pin connector and pin 2 of the TCI Sensor. Refer to section 81.2.1.1.
[b] If the resistance is greater than 5 Ω, go to step 7.
7. Disconnect the 120–pin MCM connector.
8. Measure resistance between pin 27 and pin 28 of the 31–pin connector on the engine side.
[a] If the resistance is less than 10 Ω, repair the short between pin 27 and pin 28 between
the 31–pin connector and the 120–pin MCM connector. Refer to section 81.2.1.1.
[b] If the resistance is greater than 10 Ω, go to step 9.
9. Measure resistance between pin 27 of the 31–pin connector and ground on the engine side.
[a] If the resistance is less than 5 Ω, repair the short to ground between pin 27 of the
31–pin connector and ground. Refer to section 81.2.1.1.
[b] If the resistance is greater than 5 Ω, go to step 10.
10. Measure resistance between pin 28 of the 31–pin connector and ground on the engine side.
[a] If the resistance is less than 5 Ω, repair the short to ground between pin 28 of the
31–pin connector and ground. Refer to section 81.2.1.1.
[b] If the resistance is greater than 5 Ω, contact the Detroit Diesel Customer Support
Center (313–592–5800) for authorization to replace the MCM.
All information subject to change without notice.
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(Rev. )
MBE 4000 DDEC VI TROUBLESHOOTING GUIDE
81-5