DD15 SPN 723/FMI 4 Troubleshooting

SPN 723/FMI 4

A typical diagnosis is a short to ground.‪

Check as follows:‪

1. Disconnect the CMP Sensor.
2. Measure the resistance between pin 1 of the CMP 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 CMP Sensor.Refer to “73.2.1 Verify Repairs” .
3. Measure the resistance between pin 2 of the CMP 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 CMP Sensor.Refer to “73.2.1 Verify Repairs” .
4. Disconnect 120-pin MCM connector.
5. Measure the resistance across pins 1 and 2 of the CMP harness connector.
   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 pins 1 and 2 of the CMP harness connector and pins 44 and 45 of the 120–pin MCM connector. Refer to “73.2.1 Verify Repairs” .
6. Measure the resistance between pin 1 of the CMP harness connector 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, repair the short to ground between pin 1 of the CMP harness connector and pin 44 of the 120–pin MCM connector. Refer to “73.2.1 Verify Repairs” .
7. Measure the resistance between pin 2 of the CMP harness connector and pin 45 of the 120–pin MCM connector.
   1. If the resistance is greater than 5 Ω, review the previous steps . If the results are the same, contact 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 CMP harness connector and pin 45 of the 120–pin MCM connector. Refer to “73.2.1 Verify Repairs” .

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.
   

   ENGINE EXHAUST ‪
   To avoid injury from inhaling engine exhaust, always operate the engine in a well-ventilated area. Engine exhaust is toxic.‪

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.