Section 91.4
SPN 2629/FMI 21

This condition is typically temperature too low from the turbo outlet.‪

Section 91.4.1
Turbocharger Check

Check as follows:‪

1. Disconnect the TCO Sensor.
2. Measure the resistance across pins 1 and 2 of the TCO Sensor.
   1. If the resistance is greater than 500k Ω, replace the TCO Sensor. Refer to "91.4.1.1 Verify Repairs" .
   2. If the resistance is less than 300k Ω, go to step 3 .
3. Turn the ignition ON (key On, engine OFF).
4. Measure the voltage between pins 1 and 2 of the TCO Sensor harness connector.
   1. If the voltage is between 2.75 and 3.25 volts, go to step 6 .
   2. If the voltage is less than 2.75 volts, go to step 5 .
5. Measure the voltage between pin 2 of the TCO Sensor harness connector and ground.
   1. If the voltage is between 2.75 and 3.25 volts, repair the open circuit between pin 1 of the TCO Sensor harness connector and pin 52 of the 120–pin MCM connector. Refer to "91.4.1.1 Verify Repairs" .
   2. If the voltage is less than 2.75 volts, repair the open circuit between pin 2 of the TCO Sensor harness connector and pin 112 of the 120–pin MCM connector. Refer to "91.4.1.1 Verify Repairs" .
6. Inspect the intake air and turbocharger outlet plumbing for leaks or cracks.
   1. Repair if necessary. Refer to "91.4.1.1 Verify Repairs" .
   2. If no repairs are necessary, go to the next step.
7. Perform the turbo hysterisis test
   1. If the test fails, replace the turbo actuator. Refer to "91.4.1.1 Verify Repairs" .
   2. If the test is a pass, go to step 8 .
8. Disconnect the Turbo Out Temperature Sensor.
   1. Inspect the connectors for damage, corrosion, spread or bent pins. Repair if necessary. Refer to "91.4.1.1 Verify Repairs" .
   2. If the connectors are OK, replace the Turbo Out Temperature Sensor. Refer to "91.4.1.1 Verify Repairs" .

Section 91.4.1.1
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.