Series 60 DDEC V Troubleshooting – Section 29.2 Troubleshooting Flash Code 23, PID 174/FMI 3

Section 29.2
Troubleshooting Flash Code 23, PID 174/FMI 3

This diagnostic condition is typically:‪

• Open sensor signal circuit
• Open sensor circuit return
• Sensor signal circuit is shorted to the sensor +5 volt supply

Note: This code will only be logged during warm engine operation.

The following procedure will troubleshoot Flash Code 23.‪

Section 29.2.1
Sensor Check

Perform the following steps to check the FTS/SFT Sensor:‪

1. Turn ignition OFF.
2. Disconnect the FTS/SFT Sensor connector.
3. Install a jumper wire between sockets 1 and 2 of the FTS/SFT Sensor harness connector. see Figure "Supply Fuel Temperature Sensor" .
   

   Figure 1. Supply Fuel Temperature Sensor

4. Turn ignition ON.
5. Read active codes.
   1. If code p 174/4 and any other codes except code p 174/3 are logged, refer to "29.2.2 Check for Short to +5 Volt Line" .
   2. If any code except p 174/4 is logged, refer to "29.2.3 Open Line Check" .

Section 29.2.2
Check for Short to +5 Volt Line

Perform the following steps to check for a short to the +5 volt line.‪

1. Turn ignition OFF.
2. Remove jumper wire.
3. Disconnect the Engine Harness connector at the ECM/ECU.
4. Measure resistance between sockets E-9 and E-14 on the Engine Harness connector. See Figure "ECM/ECU Engine Harness Connector" .
   1. If the measured resistance is greater than 100 Ω or open, go to step 5 .
   2. If the measured resistance is less than or equal to 100 Ω, the signal line E-9 is shorted to the engine +5 volt line. Repair the short; refer to "29.2.3.1 Verify Repairs" .
   

   Figure 2. ECM/ECU Engine Harness Connector

5. Check terminals at the FTS/SFT Sensor harness connector (both sensor and harness side) for bent, corroded, and unseated pins or sockets. See Figure "Supply Fuel Temperature Sensor" .
   

   Figure 3. Supply Fuel Temperature Sensor

   1. If terminals and connectors are damaged, repair them. Refer to "29.2.3.1 Verify Repairs" .
   2. If terminals and connectors are not damaged, replace the FTS/SFT Sensor. Refer to "29.2.3.1 Verify Repairs" .

Section 29.2.3
Open Line Check

Perform the following steps to check for an open line.‪

1. Turn ignition OFF.
2. Disconnect the Engine Harness connector at the ECM/ECU. The jumper wire is still in place at the FTS/SFT Sensor connector.
3. Measure resistance between sockets E-9 and E-14 on the Engine Harness connector. See Figure "ECM/ECU Engine Harness Connector" .
   1. If the measured resistance is greater than 5 Ω or open, the signal line E-9 or return line E-14 is open. Repair the open; refer to "29.2.3.1 Verify Repairs" .
   2. If the measured resistance is less than or equal to 5 Ω, go to step 4 .
4. Check terminals at the ECM/ECU harness connector (both ECM/ECU and harness side) for bent, corroded, and unseated pins or sockets. See Figure "ECM/ECU Engine Harness Connector" .
   

   Figure 4. ECM/ECU Engine Harness Connector

   1. If terminals and connectors are damaged, repair them. Refer to "29.2.3.1 Verify Repairs" .
   2. If terminals and connectors are not damaged, install a test ECM/ECU. Refer to "29.2.3.1 Verify Repairs" .

Section 29.2.3.1
Verify Repairs

Perform the following steps to verify repairs:‪

1. Turn ignition OFF and reconnect all connectors.
2. Turn ignition ON and clear codes with the diagnostic tool.
3. Start and run the engine for eight minutes.
4. Stop engine.
5. Read codes.
   1. If no codes are logged, troubleshooting is complete.
   2. If code p 174/3 and any other codes are logged, all system diagnostics are complete. Review this section from the first step to find the error. Refer to "29.2.1 Sensor Check" .
   3. If code p 174/3 is not logged, but other codes are logged, refer to "18.3 First Step for Diagnosing a Fault Within the DDEC System" .