Section 83.2
SPN 1176/FMI 4

This diagnosis is typically circuit failed low.‪

Section 83.2.1
Low Circuit Check

Check as follows:‪

1. Turn the ignition ON (key ON, engine OFF).
2. Check for multiple codes.
   1. If 1176/4, 1172/4, 3610/4, 3609/4, 3250/4, 3242/4 and 3246/4 are present, repair the open between pin 85 on the 120–pin MCM connector and the associated sensors. Refer to "83.2.1.1 Verify Repairs" .
   2. If 1176/4 and 1172/4 are present, repair the open between pin 85 on the 120–pin MCM connector and pin 2 on the Turbo Pressure/Temp Sensor. Refer to "83.2.1.1 Verify Repairs" .
   3. If only 1176/4 is present, go to step 4 .
3. Turn the ignition switch OFF.
4. Disconnect the Turbo Pressure/Temp Sensor. See Figure "Turbo Pressure/Temp Sensor" .
   

   Figure 1. Turbo Pressure/Temp Sensor

5. Measure the resistance between pins 1 and 2 of the Turbo Pressure/Temp Sensor.
   1. If the resistance is greater than 130k Ω, replace the Turbo Pressure/Temp Sensor. Refer to "83.2.1.1 Verify Repairs" .
   2. If the resistance is less than 130k Ω, go to step 6 .
6. Measure the resistance between pins 1 and 4 of the Turbo Pressure/Temp Sensor.
   1. If the resistance is greater than 130k Ω, replace the Turbo Pressure/Temp Sensor. Refer to "83.2.1.1 Verify Repairs" .
   2. If the resistance is less than 130k Ω, go to step 7 .
7. Disconnect the 120–pin MCM connector.
8. Measure the resistance between pins 1 and 4 of the Turbo Pressure/Temp Sensor harness connector.
   1. If the resistance is greater than 5 Ω, go to step 9 .
   2. If the resistance is less than 5 Ω, repair the short between wires 120 and 105 of the 120–pin MCM connector. See Figure "Turbo Pressure/Temp Sensor Wiring" . Refer to "83.2.1.1 Verify Repairs" .
9. Measure the voltage between pin 1 of the Turbo Pressure/Temp Sensor and ground.
   1. If the resistance is greater than 5 Ω, repair the open between pin 1 of the Turbo Pressure/Temp Sensor and pin 120 of the 120–pin MCM connector. See Figure "Turbo Pressure/Temp Sensor Wiring" . Refer to "83.2.1.1 Verify Repairs" .
   

   Figure 2. Turbo Pressure/Temp Sensor Wiring

   2. If the resistance is less than 5 Ω, repair the short to ground circuit between pin 120 of the 120–pin MCM connector and ground. See Figure "Turbo Pressure/Temp Sensor Wiring" . Refer to "83.2.1.1 Verify Repairs" .

Section 83.2.1.1
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.