DD15 SPN 723/FMI 3 Troubleshooting

SPN 723/FMI 3

The diagnostic condition is typically an open circuit.‪

Check as follows:‪

1. Disconnect CMP Sensor
2. Measure the resistance across pins 1 and 2 of the CMP Sensor.
   1. If the resistance is less than 140 Ω, go to the next step.
   2. If the resistance is greater than 140 Ω, replace the CMP Sensor. Refer to “73.1.1 Verify Repairs” .
3. Disconnect the 120–pin MCM connector.
4. Measure the resistance across pins 1 and 2 of the CMP harness connector.
   1. If the resistance is less than 5 Ω, repair short between pins 1 and 2 of the CMP harness connector and the pins 44 and 45 of the MCM 120 pin connector. Refer to “73.1.1 Verify Repairs” .
   2. If the resistance is greater than 5 Ω, go to the next step.
5. Measure the resistance between pin 1 of the CMP harness connector and pin 44 of the MCM 120 pin connector
   1. If the resistance is greater then 5 ohms, repair open between pin 1 of the CMP harness connector and pin 44 of the MCM 120 pin connector. Refer to “73.1.1 Verify Repairs” .
   2. If the resistance is less than 5 Ω, go to the next step.
6. Measure the resistance between pin 2 of the CMP harness connector and pin 45 of the MCM 120 pin connector.
   1. If the resistance is greater then 5 ohms, repair open between pin 2 of the CMP harness connector and pin 45 of the MCM 120 pin connector. Refer to “73.1.1 Verify Repairs” .
   2. If the resistance is less than 5 Ω, review the previous steps. If the results are the same, contact the Detroit Diesel Customer Support Center (313–592–5800).

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.