Section 56.3
SPN 636/FMI 4

This diagnostic condition is typically the CKP Sensor shorted to ground.‪

Section 56.3.1
Short to Ground Check

Check as follows:‪

1. Disconnect the CKP Sensor.
2. Measure the resistance between pin 1 of the CKP Sensor and ground.
   1. If the resistance is greater than 5 Ω, go to step 3 .
   2. If the resistance is less than 5 Ω, replace the sensor. Refer to "56.3.1.1 Verify Repairs" .
3. Measure the resistance between pin 2 of the CKP Sensor and ground.
   1. If the resistance is greater than 5 Ω, go to step 4 .
   2. If the resistance is less than 5 Ω, replace the sensor. Refer to "56.3.1.1 Verify Repairs" .
4. Disconnect the 120–pin MCM connector.
5. Measure the resistance across pins 1 and 2 of the CKP Sensor harness connector.
   1. If the resistance is greater than 5 Ω, go to step 6 .
   2. If the resistance is less than 5 Ω, repair the short between the CKP Sensor harness connector pins 1 and 2 and pins 42 and 43 of the 120–pin MCM connector. Refer to "56.3.1.1 Verify Repairs" .
6. Measure the resistance between pin 1 of the CKP Sensor harness connector and ground.
   1. If the resistance is greater than 5 Ω, go to step 7 .
   2. If the resistance is less than 5 Ω, repair the short to ground between pin 1 of the CKP Sensor harness connector and pin 42 of the 120–pin MCM connector. Refer to "56.3.1.1 Verify Repairs" .
7. Measure the resistance between pin 2 of the CKP Sensor harness connector and pin 43 of the 120–pin MCM connector.
   1. If the resistance is greater than 5 Ω, reconnect the 120–pin MCM connector and review steps 2 through 7 . If the results are the same, call the Detroit Diesel Customer Support Center (313–592–5800).
   2. If the resistance is less than 5 Ω, repair the short to ground between pin 2 of the CKP Sensor harness connector and pin 43 of the 120–pin MCM connector. Refer to "56.3.1.1 Verify Repairs" .

Section 56.3.1.1
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.