3500B Industrial Engines Caterpillar

System Operation Description:

Engine sensors provide various signals to the engine ECM. These sensors receive a regulated voltage from the ECM. Analog sensors receive 5.0 ± 0.5 VDC and digital sensors receive 8.0 ± 0.5 VDC.

The ECM performs an automatic calibration of these sensors whenever the ECM is powered and the engine is off for at least five seconds. During an automatic calibration, the ECM calibrates pressure sensors against the Atmospheric Pressure Sensor and an acceptable offset pressure range.

Illustration 1	g00748437

Test Step 1. Check the Electrical Connectors and the Wiring.

1. Turn the Battery switch for the ECM to the OFF position.

2. Turn the breaker at the battery to the OFF position.

3. Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.

4. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.

5. Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).

6. Check the customer connector (allen head screw) for the proper torque of 2.25 ± 0.25 N·m (20 ± 2 lb in).

7. Check the harness and the wiring for abrasion and pinch points.

Expected Result:

All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring should be free of corrosion, abrasion or pinch points.

Results:

• OK - The wiring and connectors are okay. Proceed to Test Step 2.

• Not OK - Repair the wiring and connectors or replace the wiring or the connectors. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem.STOP

Test Step 2. Check for Active Diagnostic Codes.

1. Connect the ET.

2. Turn the breaker at the battery to the ON position.

3. Turn the Battery switch for the ECM to the ON position.

4. Go to the active diagnostics screen.

5. Wait for 15 seconds for the CID-FMI.

Expected Result:

Determine the failure mode identifier (FMI). Determine if the diagnostic codes 262-03 5 Volt Sensor Supply short to +batt or 262-04 5 Volt Sensor Supply short to ground are present. Determine if the diagnostic codes 263-03 Digital Sensor Supply short to +batt or 263-04 Digital Sensor Supply short to ground are present.

Results:

• FMI 03 - A diagnostic code with a FMI of 03 is present. Proceed to test step 3.

• FMI 04 - A diagnostic code with a FMI of 04 is present. Proceed to test step 4.

• FMI 00 or 08 - A diagnostic code with a FMI of 00 or 08 is present. Proceed to test step 10.

• 262-03 or 262-04 Active Code - A diagnostic code of 262-03 or 262-04 is present.

  Repair: Perform a diagnostic functional test. Refer to Troubleshooting, "Analog Sensor Supply".

  STOP

• 263-03 or 263-04 Active Code - A diagnostic code of 263-03 or 263-04 is present.

  Repair: Perform a diagnostic functional test. Refer to Troubleshooting, "Digital Sensor Supply".

  STOP

Test Step 3. Check the Sensor Supply Voltage at the Sensor Connector if the Diagnostic Code FMI-03 is Present.

1. Turn the Battery switch for the ECM to the OFF position.

2. Disconnect the suspect sensor.

   Note: Disconnecting the sensor will generate an open circuit diagnostic code for any sensor that is disconnected. Troubleshoot the original diagnostic code. Reset the system. Delete the logged diagnostic codes when you are finished.

3. Turn the Battery switch for the ECM to the ON position.

4. Measure the voltage between pin A and pin B for the suspect sensor.

Expected Result:

The supply voltage should be 5.0 ± 0.5 VDC for all analog sensors and 8.0 ± 0.5 VDC for all digital sensors.

Results:

• OK - The voltage is 5.0 ± 0.5 VDC for all analog sensors and 8.0 ± 0.5 VDC for all digital sensors. Proceed to test step 5.

• Not OK - The voltage is not 5.0 ± 0.5 VDC for all analog sensors and 8.0 ± 0.5 VDC for all digital sensors. Proceed to test step 6.

Test Step 4. Check the Sensor Supply Voltage at the Sensor Connector if the Diagnostic Code FMI-04 is Present.

1. Turn the Battery switch for the ECM to the OFF position.

2. Disconnect the suspect sensor.

   Note: Disconnecting the sensor will generate an open circuit diagnostic code for any sensor that is disconnected. Troubleshoot the original diagnostic code. Reset the system. Delete the logged diagnostic codes when you are finished.

3. Turn the Battery switch for the ECM to the ON position.

4. Measure the voltage between pin A and pin B for the suspect sensor.

Expected Result:

The supply voltage should be 5.0 ± 0.5 VDC for all analog sensors and 8.0 ± 0.5 for all digital sensors.

Results:

• OK - The voltage is 5.0 ± 0.5 VDC for all analog sensors and 8.0 ± 0.5 VDC for all digital sensors. Proceed to test step 7.

• Not OK - The voltage is not 5.0 ± 0.5 VDC for all analog sensors and 8.0 ± 0.5 VDC for all digital sensors. Proceed to test step 6.

Test Step 5. Install a Jumper Wire.

1. Turn the Battery switch for the ECM to the OFF position.

2. Use a wire with socket terminals at each end. Connect pin B and pin C together on the ECM side of the sensor connector.

3. Turn the Battery switch for the ECM to the ON position.

4. Check if the CID-FMI has changed from 03 to 04.

5. Turn the Battery switch for the ECM to the OFF position.

6. Remove the wire short.

Expected Result:

The CID-FMI should change from 03 to 04.

Results:

• OK - The CID-FMI changed from 03 to 04. The circuit now indicates a short circuit diagnostic code.

  Repair: Temporarily connect a new sensor. Verify that the new sensor solves the problem before you permanently install the new sensor. Calibrate the sensor.

  STOP

• Not OK - The CID-FMI did not change from 03 to 04. The circuit indicates an open circuit diagnostic code. Proceed to test step 8.

Test Step 6. Check the Sensor Supply Voltage at the ECM.

1. Turn the Battery switch for the ECM to the OFF position.

2. Install a Breakout T at ECM connector J1/P1.

3. Check the analog supply voltage by removing wires P1-36 (997-OR) and P1-30 (993-BR) from one side of the Breakout T.

   Check the digital supply voltage by removing wires P1-35 (700-OR) and P1-29 (998-BR) from one side of the Breakout T.

   Note: If you remove the sensor common from the ECM an open circuit diagnostic code will be generated for all sensors that use the sensor common. Troubleshoot the original code. Delete the logged diagnostic codes when you are finished.

4. Turn the Battery switch for the ECM to the ON position.

5. Measure the analog voltage between P1-36 (997-OR) and P1-30 (993-BR) at the Breakout T.

6. Measure the digital voltage between P1-35 (700-OR) and P1-29 (998-BR) at the Breakout T.

7. Turn the Battery switch for the ECM to the OFF position.

Expected Result:

The supply voltage should be 5.0 ± 0.5 VDC for all analog sensors and 8.0 ± 0.5 for all digital sensors.

Results:

• OK - Analog or Digital - The supply voltage is 5.0 ± 0.5 VDC for all analog sensors and 8.0 ± 0.5 for all digital sensors. The supply voltage at the ECM is correct. There is a problem in the wiring between the ECM and the suspect sensor.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

• Not OK - Analog or Digital - The supply voltage is not 5.0 ± 0.5 VDC for all analog sensors and 8.0 ± 0.5 for all digital sensors. The voltage at the ECM is not correct.

  Repair: Perform a diagnostic functional test. Refer to Troubleshooting, "Electrical Power Supply".

  STOP

Test Step 7. Create an Open Circuit at the Sensor Connector.

1. Turn the Battery switch for the ECM to the OFF position.

2. Turn the Battery switch for the ECM to the ON position.

3. The CID-FMI should change from 04 to 03.

   Note: Disconnecting the Atmospheric Pressure Sensor will cause several sensor diagnostic codes to become active. Troubleshoot the original code. Reset the system. Delete the logged diagnostic codes when you are finished.

4. Reconnect the suspect sensor.

Expected Result:

The CID-FMI should change from 04 to 03 when the sensor is disconnected.

Results:

• OK - The CID-FMI changed from 04 to 03 when the sensor was disconnected. The open circuit was seen by the ECM. The wiring between the ECM and the sensor is good.

  Repair: Replace the suspect sensor. Verify that the repair eliminates the problem.

  STOP

• Not OK - The CID-FMI did not change from 04 to 03 when the sensor was disconnected. The open circuit was not seen at the ECM. Proceed to test step 9.

Test Step 8. Install a Jumper Wire at the ECM Connector.

1. Connect the suspect sensor.

2. Install a Breakout T at ECM connector J1/P1 and J2/P2.

3. Remove the suspect sensor's signal wire from the Breakout T at P2. Remove the suspect sensor's return wire from the Breakout T at P1. Install a jumper wire between the signal wire and the return wire.

   Note: If you remove the sensor common from the ECM an open circuit diagnostic code will be generated for all sensors that use the sensor common. Troubleshoot the original code. Delete the logged diagnostic codes when you are finished.

4. Turn the Battery switch for the ECM to the ON position.

5. The CID-FMI should change from 03 to 04 when the jumper is in place.

6. Turn the Battery switch for the ECM to the OFF position.

7. Remove the Breakout T and reconnect ECM connectors.

Expected Result:

The CID-FMI should change from 03 to 04 when the jumper is in place.

Results:

• OK - The CID-FMI changed from 03 to 04 when the jumper was put in place. The ECM recognized the short at the ECM. There is a problem with the wiring between the ECM and the suspect sensor.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

• Not OK - The CID-FMI did not change from 03 to 04 when the jumper was put in place. The ECM did not see the short at the ECM. Replace the ECM.

  Repair: Refer to Troubleshooting, "Replacing the ECM".

  STOP

Test Step 9. Create an Open at the ECM.

1. Turn the Battery switch for the ECM to the OFF position.

2. Install a Breakout T at ECM connector J1/P1 or J2/P2.

3. Disconnect the suspect sensor signal wire from the Breakout T.

4. Turn the Battery switch for the ECM to the ON position.

5. Check if the CID-FMI has changed from 04 to 03.

   Note: Disconnecting the Atmospheric Pressure Sensor will cause several sensor diagnostic codes to become active. Troubleshoot the original code. Reset the system. Delete the logged diagnostic codes when you are finished.

Expected Result:

The CID-FMI should change from 04 to 03 when the sensor signal wire is disconnected.

Results:

• OK - The CID-FMI changed from 04 to 03 when the sensor signal wire was disconnected. The ECM recognized the open at the ECM.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

• Not OK - The CID-FMI did not change from 04 to 03 when the sensor signal wire was disconnected. The ECM did not recognize the open at the ECM.

  Repair: Refer to Troubleshooting, "Replacing the ECM".

  STOP

Test Step 10. Check the Fluid Level.

1. Check the fuel level.

2. Check the engine oil level.

3. Check for any leaks.

Expected Result:

The fuel and oil level should be okay. There should not be any leaks.

Results:

• OK - The fuel and oil levels are correct. Proceed to test step 11.

• Not OK - The fuel and/or oil levels are not correct.

  Repair: If the oil level is low, add oil. If the fuel level is low, add fuel. Repair the leaks. Reset the system and note any active diagnostic codes.

  STOP

Test Step 11. Compare the Pressure or Temperature to the Actual Pressure or Temperature.

1. Turn the Battery switch for the ECM to the OFF position.

2. If you are troubleshooting a temperature sensor, install a 6V-9130 Temperature Adapter near the sensor.

3. Turn the Battery switch for the ECM to the ON position.

4. Observe the temperature reading for the suspect sensor. The ET should display the same temperature as the 6V-9130 Temperature Adapter .

   Note: When the temperature is below 0 °C (32 °F), the temperature can vary 15 °C (59 °F).

5. If you are troubleshooting a pressure sensor, disconnect the sensor.

6. Remove the suspect sensor from the engine.

7. Connect the suspect sensor to the sensor connector.

8. Connect the vacuum pump test unit to the suspect sensor.

9. Connect the vacuum pump to the differential pressure gauge.

10. Turn the Battery switch for the ECM to the ON position.

11. Observe the pressure reading for the suspect sensor. The ET should display the barometric pressure in your area.

12. Use the vacuum pump to pull 5 kPa (0.7 psi) of vacuum on the differential pressure gauge.

    Note: The pressure gauge reading should remain constant until the vacuum is released.

13. Compare the readings on the ET and the pressure test kit.

Expected Result:

The ET should show the correct temperature. The ET should show constant pressure. The ET should show a 5 ± 2 kPa (0.7 ± 0.3 psi) drop in pressure when the vacuum is applied.

Results:

• OK - The ET shows the correct temperature. The ET shows a constant pressure. The ET shows a 5 ± 2 kPa (0.7 ± 0.3 psi) drop in pressure while the vacuum is being applied. The sensor is working correctly. Reset the system and note any active diagnostic codes.STOP

• Not OK Analog - The ET does not show a constant pressure. The ET does not show a 5 ± 2 kPa (0.7 ± 0.3 psi) drop in pressure while the vacuum is being applied. An analog sensor is not producing the correct reading. Proceed to test step 12.

• Not OK Digital - The ET does not show the correct temperature. A digital sensor is not producing the correct reading. Proceed to test step 13.

• Vacuum Leak - A vacuum leak is suspected.

  Repair: Check for leaks. If no leaks are found, there is an internal leak in the suspect pressure sensor. Replace the sensor and calibrate the sensor. Reset the system and note any active diagnostic codes.

  STOP

Test Step 12. Check the Analog Sensor's Signal Voltage at the Sensor Connector.

1. Turn the Battery switch for the ECM to the OFF position.

2. Install a Breakout T at the sensor connector.

3. Turn the Battery switch for the ECM to the ON position.

4. Measure the sensor signal voltage between pin C and pin B at the sensor connector.

5. Remove the Breakout T and reconnect the sensor.

Expected Result:

The signal voltage should be between 0.2 VDC and 4.8 VDC for analog sensors.

Results:

• OK - The signal voltage is between 0.2 VDC and 4.8 VDC for analog sensors. Proceed to test step 16.

• Not OK - The signal voltage is not between 0.2 VDC and 4.8 VDC for analog sensors. Proceed to test step 14.

Test Step 13. Check the Digital Sensor's Signal Frequency and the Duty Cycle at the Sensor Connector.

1. Turn the Battery switch for the ECM to the OFF position.

2. Install a Breakout T at the sensor connector.

3. Turn the Battery switch for the ECM to the ON position.

4. Measure the frequency and the duty cycle between pin C and pin B of the suspect digital sensor at the sensor connector.

5. Turn the Battery switch for the ECM to the OFF position.

6. Remove the Breakout T and reconnect the sensor.

Expected Result:

The frequency reading should be between 400 Hz and 800 Hz.

When the temperature is below 49 °C (120 °F), the duty cycle should be between 16% to 21%.

When the temperature is between 49 °C (120 °F), and 851 °C (1564 °F) the duty cycle should be between 22% to 88%.

Results:

• OK - The frequency and the duty cycle are correct. Proceed to test step 17.

• Not OK - The frequency and the duty cycle are not correct. Proceed to test step 14.

Test Step 14. Check for Shorts in the Wiring Harness.

1. Turn the Battery switch for the ECM to the OFF position.

2. Disconnect the ECM connectors J1/P1 and J2/P2. Disconnect the suspect sensor.

3. Measure the resistance between the suspect sensor signal wire at the ECM connector and the supply voltage at the ECM connector.

4. Measure the resistance between the suspect sensor signal wire at the ECM connector and the sensor return line at the ECM connector.

5. Measure the resistance between the suspect sensor signal wire at the ECM connector and engine ground.

Expected Result:

The resistance should be greater than 20,000 Ohms.

Results:

• OK - The resistance is greater than 20,000 Ohms. Proceed to test step 15.

• Not OK - The resistance is less than 20,000 Ohms.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

Test Step 15. Check the Resistance through the Harness.

1. Disconnect the suspect sensor connector.

2. Use a suitable piece of wire to connect pin A to pin C.

3. Measure the resistance between suspect sensor signal wire and the suspect sensor voltage supply at the ECM connector.

4. Use a suitable piece of wire to connect pin B to pin C.

5. Measure the resistance between the sensor signal wire and the sensor return line at the ECM connector P1.

6. Turn the Battery switch for the ECM to the OFF position.

7. Remove all wire shorts.

8. Reconnect all connectors.

Expected Result:

The resistance should be less than 10 Ohms.

Results:

• OK Analog - The resistance is less than 10 Ohms. Proceed to test step 16.

• OK Digital - The resistance is less than 10 Ohms. Proceed to test step 17.

• Not OK - The resistance is greater than 10 Ohms.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

Test Step 16. Check the Analog Sensor's Signal Voltage at the ECM.

1. Turn the Battery switch for the ECM to the OFF position.

2. Install a Breakout T at ECM connector J1/P1 and/or J2/P2.

3. Remove the suspect sensor signal wire from the Breakout T. Remove the common sensor wire from the Breakout T.

   Note: Disconnecting the common sensor wire from the ECM will generate an open circuit diagnostic code for all sensors that are connected to the sensor common. Troubleshoot the original diagnostic code. Reset the system. Delete the logged diagnostic codes when you are finished.

4. Turn the Battery switch for the ECM to the ON position.

5. Measure the sensor signal voltage between pin C and pin B at the ECM connector.

6. Turn the Battery switch for the ECM to the OFF position.

7. Remove the Breakout T and reconnect the ECM connectors.

8. Turn the Battery switch for the ECM to the ON position.

9. Start the engine.

10. Observe the sensor reading on the status screen on the ET.

    Note: The status screen on the ET displays "ABNORMAL SIGNAL" when the ECM reads a signal that is out of range.

11. Shut the engine OFF.

12. Turn the Battery switch for the ECM to the OFF position.

Expected Result:

The signal voltage for the analog sensors should be between 0.2 VDC and 4.8 VDC for the suspect analog sensor.

Results:

• OK - The signal voltage for the analog sensors is between 0.2 VDC and 4.8 VDC for the suspect analog sensor. The sensor voltage at the ECM is correct. Reset the system and note any diagnostic codes.STOP

• Not OK - The signal voltage for the analog sensors is not between 0.2 VDC and 4.8 VDC for the suspect analog sensor. The sensor voltage at the ECM is not correct.

  Repair: Perform a diagnostic functional test. Refer to Troubleshooting, "Analog Sensor Supply".

  STOP

• Intermittent Problem - The readings are not consistent.

  Repair: Perform a diagnostic test. Refer to Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• ABNORMAL SIGNAL - The status screen on the ET displays "ABNORMAL SIGNAL". The signal is out of range.

  Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM".

  STOP

Test Step 17. Check the Digital Sensor's Signal Frequency and the Duty Cycle at the ECM.

1. Turn the Battery switch for the ECM to the OFF position.

2. Install a Breakout T at the sensor connector.

3. Remove the suspect sensor signal wire from the Breakout T. Remove the common sensor wire from the Breakout T.

   Note: Disconnecting the common sensor wire from the ECM will generate an open circuit diagnostic code for all sensors that are connected to the sensor common. Troubleshoot the original diagnostic code. Reset the system. Delete the logged diagnostic codes when you are finished.

4. Use a wire with socket terminals at each end. Connect the jumper between the sensor signal and the sensor return at the Breakout T.

5. Turn the Battery switch for the ECM to the ON position.

6. Measure the frequency and the duty cycle between pin C and pin B of the suspect digital sensor at the sensor connector.

7. Turn the Battery switch for the ECM to the OFF position.

8. Remove the Breakout T and reconnect the ECM connectors.

9. Turn the Battery switch for the ECM to the ON position.

10. Start the engine.

11. Observe the sensor reading on the status screen on the ET.

    Note: The status screen on the ET displays "ABNORMAL SIGNAL" when the ECM reads a signal that is out of range.

12. Shut the engine OFF.

13. Turn the Battery switch for the ECM to the OFF position.

Expected Result:

The frequency reading should be between 400 Hz and 800 Hz.

When the temperature is below 49 °C (120 °F), the duty cycle should be between 16% to 21%.

When the temperature is between 49 °C (120 °F), and 851 °C (1564 °F) the duty cycle should be between 22% to 88%.

While the engine is cold, the ET should read 30 °C (86 °F). As the engine warms up the exhaust temperature should increase.

Results:

• OK - The digital sensor voltage at the ECM is correct. Reset the system and note any diagnostic codes.STOP

• Not OK - The digital sensor voltage at the ECM is not correct.

  Repair: Perform a diagnostic functional test. Refer to Troubleshooting, "Digital Sensor Supply".

  STOP

• Intermittent Problem - The readings are not consistent.

  Repair: Perform a diagnostic test. Refer to Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• ABNORMAL SIGNAL - The status screen on the ET displays "ABNORMAL SIGNAL". The signal is out of range.

  Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM".

  STOP