MBE 900 DDEC VI Troubleshooting – Section 55.2 SPN 636/FMI 3

Section 55.2
SPN 636/FMI 3

The diagnostic condition is typically CKP Sensor has an open circuit.‪

Section 55.2.1
Open Circuit Check

Check as follows:‪

1. Disconnect the CKP Sensor.
2. Measure the resistance across pins 1 and 2 of the CKP Sensor. See Figure "Crankshaft Position Sensor Wiring" .
   

   Figure 1. Crankshaft Position Sensor Wiring

   1. If the resistance is greater than 1400 Ω or less than 1000 Ω, replace CKP Sensor. Refer to "55.2.2.1 Verify Repairs" .
   2. If the resistance is between 1000 Ω and 1400 Ω, go to step 3 .
3. Disconnect the 120–pin MCM connector.
4. 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 5 .
   2. If the resistance is less than 5 Ω, repair the short between pins 1 and 2 of the CKP Sensor harness connector and pins 73 and 43 of the 120–pin MCM connector. Refer to "55.2.2.1 Verify Repairs" .
5. Measure the resistance between pin 1 of the CKP Sensor harness connector and pin 73 of the 120–pin MCM connector.
   1. If the resistance is greater than 5 Ω, repair the open between pin 1 of the CKP Sensor harness connector and pin 73 of the 120–pin MCM connector. Refer to "55.2.2.1 Verify Repairs" .
   2. If the resistance is less than 5 Ω, go to step 6 .
6. 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, repair the open between pin 2 of the CKP Sensor harness connector and pin 43 of the 120–pin MCM connector. Refer to "55.2.2.1 Verify Repairs" .
   2. If the resistance is less than 5 Ω, refer to "55.2.2 Crankshaft Position Sensor Gap Check" .

Section 55.2.2
Crankshaft Position Sensor Gap Check

Check the crankshaft position sensor gap as follows:‪

1. Bar the engine until the CKP Sensor is over a CKP tooth of the pulse wheel.
2. Check the gap between the CKP Sensor and the tooth of the pulse wheel (0.020 to 0.040 in.). A depth micrometer can be used.
   1. If the gap setting is correct, repeat steps 1 and 2 . If the results are the same, call the Detroit Diesel Customer Support Center (313–592–5800).
   2. If the gap setting is not correct, adjust the CKP Sensor until the gap setting is correct and refer to "55.2.2.1 Verify Repairs" . If the problem returns, the pulse wheel may be loose or bad or damaged.

Section 55.2.2.1
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.