Series 60 DDEC V Troubleshooting – Section 33.2 Troubleshooting Flash Code 28, PID 172/FMI 4

Section 33.2
Troubleshooting Flash Code 28, PID 172/FMI 4

This diagnostic condition is typically sensor signal circuit is shorted to sensor return or shorted to ground.‪

Section 33.2.1
Multiple Code Check

Perform the following steps to check for multiple codes.‪

1. Turn vehicle ignition switch ON.
2. Plug in the diagnostic tool. Read active codes.
   1. If code p 172/4 was logged and there are no other codes logged, refer to "33.2.2 Sensor Check" .
   2. If code p 172/4 and any of the following codes p 110/3, p 175/3, p 174/3, p 72/3 or p 102/3 were logged, refer to "79 Engine Harness" .
   3. If code p 172/4 and any code except the following were logged p 110/3, p 175/3, p 174/3, p 72/3 or p 102/3, refer to "33.2.2 Sensor Check" .

Section 33.2.2
Sensor Check

Perform the following steps to check the sensor.‪

1. Turn vehicle ignition OFF.
2. Disconnect the ATS connector. See Figure "Engine Harness to Air Temperature Sensor Connector" .
3. Start engine and run until the Check Engine Light/Amber Warning Lamp comes on or for eight minutes.
4. With engine still running, read active codes.
   1. If code p 172/4 and any other codes were logged, refer to "33.2.3 Check for Short" .
   2. If p 172/3 and any other codes except p 172/4 were logged, go to step 5 .
   

   Figure 1. Engine Harness to Air Temperature Sensor Connector

5. Check terminals at the ATS connector (both sensor and harness side) for damage; bent, corroded and unseated pins or sockets.
   1. If terminals and connectors are not damaged, replace ATS. Refer to "33.2.3.1 Verify Repairs" .
   2. If terminals and connectors are damaged, repair/replace wires and refer to "33.2.3.1 Verify Repairs" .

Section 33.2.3
Check for Short

Perform the following steps to check for a short.‪

1. Turn the ignition OFF.
2. Disconnect the engine harness connector at the ECM/ECU.
3. Measure resistance between sockets E-2 and E-14 on the engine harness connector. See Figure "ECM/ECU Engine Harness Connector" .
4. Measure resistance between socket E-2 and a good ground.
   1. If the resistance measurement between sockets E-2 and E-14 and between socket E-2 and a good ground is greater than 10 Ω or open, go to step 5 .
   2. If the resistance measurement between sockets E-2 and E-14 , or E-2 and battery negative, is less than or equal to 10 Ω, the signal line E-2 is shorted to the return line E-14 or battery ground. Repair short. Refer to "33.2.3.1 Verify Repairs" .
5. Check terminals at the ECM/ECU harness connector (both ECM/ECU and harness side) for damage; bent, corroded and unseated pins or sockets, especially E-2 and E-14 of the ECM/ECU connector.
   

   Figure 2. ECM/ECU Engine Harness Connector

   1. If terminals or connectors are not damaged, contact Detroit Diesel Customer Support Center (313–592–5800) and refer to "33.2.3.1 Verify Repairs" .
   2. If terminals and connectors are damaged, repair them. Refer to "33.2.3.1 Verify Repairs"

Section 33.2.3.1
Verify Repairs

‪

Perform the following steps to verify repairs.‪

1. Turn ignition OFF.
2. Reconnect all connectors.
3. Turn the ignition ON. Clear codes.
4. Start and run the engine for eight minutes. Stop the engine.
5. Read inactive codes.
   1. If no codes are displayed, troubleshooting is complete.
   2. If code p 172/4 is logged with any other codes, all system diagnostics are complete. Review this section from the first step to find the error.
   3. If code p 172/4 is not logged, but other codes are logged, refer to "18.3 First Step for Diagnosing a Fault Within the DDEC System" .