84.1 SPN 1172/FMI 2
This code is typically a coolant temperature/compressor inlet temperature plausibility error.
84.1.1
Turbo Compressor Inlet Temperature Sensor Check
Check as follows:
1. Disconnect the Turbo Compressor Inlet Temperature Sensor.
2. Inspect the Turbo Compressor Inlet Temperature Sensor connectors for bent, damaged or
corroded pins.
[a] If damaged pins are found, repair as necessary. Refer to section 84.1.1.1.
[b] If no damage is found, replace the Turbo Compressor Inlet Temperature Sensor.
Refer to section 84.1.1.1.
84.2 SPN 1172/FMI 3
This code is typically sensor or circuit failed high.
84.2.1
Open Circuit Check
Check as follows:
1. Turn the ignition ON (key ON, engine OFF).
2. Check for multiple codes.
[a] If 1172/3, 3250/3, 3242/3 and 3246/3 are present, go to step 3.
[b] If only 1172/3 is present, go to step 5
3. Disconnect the Turbo Compressor Inlet Temperature Sensor (TCI Sensor).
4. Measure the voltage between pin 1 of the TCI Sensor and ground.
[a] If the voltage is greater than 2.75 volts, repair the short to power between pin
88 of the 120–pin MCM connector and the TCI Sensor, DOC Inlet Temperature
Sensor, DOC Outlet Temperature Sensor and the DPF Outlet Temperature Sensor.
Refer to section 84.2.1.1.
[b] If no voltage is present on pin 1 of the Intake Air Temperature Sensor, repair the
open between pin 88 of the 120–pin MCM connector and the TCI Sensor, DOC
Inlet Temperature Sensor, DOC Outlet Temperature Sensor and the DPF Outlet
Temperature Sensor. Refer to section 84.2.1.1.
5. Disconnect the Turbo Compressor Inlet Temperature Sensor.
6. Measure the voltage between pin 1 and pin 2 of the Turbo Compressor Inlet Temperature
Sensor.
[a] If the voltage is less than 2.75 volts, go to step 7.
[b] If the voltage is greater than 2.75 volts, replace the sensor. Refer to section 84.2.1.1.
7. Measure the voltage between pin 2 of the Turbo Compressor Inlet Temperature Sensor
and ground.
[a] If the voltage is less than 2.75 volts, repair the open between pin 2 of the Turbo
Compressor Inlet Temperature Sensor and pin 86 of the 120–pin MCM connector.
Refer to section 84.2.1.1.
[b] If the voltage is greater than 2.75 volts, repair the open between pin 1 of the Turbo
Compressor Inlet Temperature Sensor and pin 86 of the 120–pin MCM connector.
Refer to section 84.2.1.1.
84.3 SPN 1172/FMI 4
This code is typically sensor or circuit failed low.
84.3.1
Short Circuit Check
Check as follows:
1. Turn the ignition OFF.
2. Disconnect the TCI Sensor.
3. Disconnect the 120–pin MCM connector.
4. Measure resistance between pin 1 and pin 2 of the TCI Sensor Harness connector.
[a] If the resistance is less than 3 Ω, repair the short between pin 1 and pin 2 of the TCI
Sensor Harness connector and pin86 and pin 88 of the 120–pin MCM connector.
Refer to section 84.3.1.1.
[b] If the resistance is greater than 3 Ω, repair the short to ground between pin 2 of the
TCI Sensor and pin 86 of the 120–pin MCM connector. Refer to section 84.3.1.1.
