MBE 900 DDEC VI Troubleshooting – Section 29.3 SPN 110/FMI 3

Section 29.3
SPN 110/FMI 3

SPN 110/FMI 3 indicates that the Engine Coolant Temperature Sensor (ECT Sensor) input to the MCM has exceeded 95% of the sensor supply voltage. The diagnostic condition is typically engine coolant temperature open circuit (110/3). ‪

Section 29.3.1
Open Circuit Check

Check as follows:‪

1. Check for multiple codes.
   1. If codes 110/3, 174/3 and 175/3 are active at the same time, repair the open circuit between pin 73 of the 120–pin MCM connector and pin 1 of the ECT Sensor, the EOT Sensor and the Supply Fuel Temperature Sensor. Refer to "29.3.1.1 Verify Repairs" .
   2. If only fault 110/3 is active, go to step 2 .
2. Disconnect the ECT Sensor. See Figure "Engine Coolant Temperature Sensor" .
   

   Figure 1. Engine Coolant Temperature Sensor

3. Measure the resistance across pins 1 and 2 of the ECT Sesnor.
   1. If the resistance is greater than 4 kΩ, replace the sensor. Refer to "29.3.1.1 Verify Repairs" .
   2. If the resistance is less than 4 kΩ, go to step 4 .
4. Turn the ignition ON.
5. Measure the voltage between pins 1 and 2 of the ECT Sensor harness connector.
   1. If the voltage is between 2.75 and 3.25 volts, go to step 7 .
   2. If the voltage is less than 2.75 volts, go to step 6 .
6. Measure the voltage between pin 2 of the ECT Sensor harness connector and ground.
   1. If the voltage is between 2.75 and 3.25 volts, repair the open circuit between pin 1 of the ECT Sensor harness connector and pin 73 of the 120–pin MCM connector (see Figure "Engine Coolant Temperature Sensor" ). Refer to "29.3.1.1 Verify Repairs" .
   2. If the voltage is less than 2.75 volts, repair the open circuit between pin 2 of the ECT Sensor harness connector and pin 110 of the 120–pin MCM connector (see Figure "Engine Coolant Temperature Sensor" ). Refer to "29.3.1.1 Verify Repairs" .
   

   Figure 2. Engine Coolant Temperature Sensor

7. Disconnect the 120–pin MCM connector. Measure the resistance between pins 1 and 2 of the ECT Sensor harness connector.
   1. If the resistance is greater than 5 Ω, replace the ECT Sensor. Refer to "29.3.1.1 Verify Repairs" .
   2. If the resistance is less than 5 Ω, repair the short between pins 73 and 110 of the 120–pin MCM connector. Refer to "29.3.1.1 Verify Repairs" .

Section 29.3.1.1
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.