MBE 4000 DDEC VI Troubleshooting – Section 54.1 SPN 636/FMI 1

Section 54.1
SPN 636/FMI 1

The diagnostic condition is typically CKP Sensor Signal Voltage Too Low.‪

Section 54.1.1
Low Signal Voltage 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 the next step.
   2. If the resistance is less than 5 Ω, replace the sensor. Refer to "55.1.1.1 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 the next step.
   2. If the resistance is less than 5 Ω, replace the sensor. Refer to "55.1.1.1 Verify Repairs" .
4. Disconnect the 120–pin MCM connector.
5. Measure the resistance across pins 1 and 2 of the CKP Sensor harness connector. See Figure "Crankshaft Position Sensor Wiring" .
   

   Figure 1. Crankshaft Position Sensor Wiring

   1. If the resistance is greater than 5 Ω, go to the next step.
   2. If the resistance is less than 5 Ω, repair the short between the CKP Sensor harness connector pins 1 and 2 and pins 73 and 43 of the 120–pin MCM connector. Refer to "55.1.1.1 Verify Repairs" .
6. Measure the resistance between pin 1 of the CKP Sensor harness connector and ground.
   1. 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 "55.1.1.1 Verify Repairs" .
   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 "55.1.1.1 Verify Repairs" .

Section 54.1.1.1
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.