3512B Petroleum Engines with the ADEM 2 Electronic Control Module Caterpillar

Engine sensors provide various signals to the engine Electronic Control Module (ECM). These sensors receive a regulated voltage from the ECM. Analog sensors receive 5.0 ± 0.2 VDC and digital sensors receive 8.0 ± 0.4 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	g00820834

Test Step 1. Check for Connector Damage.

1. Turn the main disconnect to the OFF position.

2. Turn the engine control to the OFF position.

3. Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to the diagnostic functional test 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:

The connectors and wiring should be free of the following problems: damage, corrosion, abrasion and incorrect attachment.

Results:

• OK - The connectors and wiring are okay. Proceed to test step 2.

• Not OK - The connectors and/or wiring are not okay.

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

  STOP

Test Step 2. Check for "ACTIVE" Diagnostic Codes.

1. Start the Caterpillar Electronic Technician (ET).

2. Turn the main disconnect to the ON position.

3. Turn the engine control to the ON position. The engine should be off.

4. 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 DC Power Supply short to +batt and/or 262-04 5 Volt Sensor DC Power Supply short to ground are present. Determine if the diagnostic codes 263-03 Digital Sensor Supply short to +batt and/or 263-04 Digital Sensor Supply short to ground are present.

Results:

• 262-03 or 262-04 Active Code - A diagnostic code of 263-03 or 263-04 is present.

  Repair: Perform the diagnostic functional test 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 the diagnostic functional test Troubleshooting, "Digital Sensor Supply".

  STOP

• 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 08 - A diagnostic code with a FMI of 08 is present. Proceed to test step 11.

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

1. Turn the engine control to the OFF position.

2. Disconnect the sensor.

   Note: Disconnecting the sensor wire from the ECM will generate an open circuit diagnostic code for the sensor. Troubleshoot the original diagnostic code. Delete the logged diagnostic codes when you are finished.

3. Turn the engine control to the ON position. The engine should be off.

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

Expected Result:

The supply voltage should reach 5.0 ± 0.2 VDC for all analog sensors and 8.0 ± 0.4 for all digital sensors.

Results:

• OK - The supply voltage is 5.0 ± 0.2 VDC for all analog sensors and 8.0 ± 0.4 for all digital sensors. The voltage is correct. Proceed to test step 5.

• Not OK - The supply voltage is not 5.0 ± 0.2 VDC for all analog sensors and 8.0 ± 0.4 for all digital sensors. The voltage is out of range. Proceed to test step 7.

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

1. Turn the engine control to the OFF position.

2. Disconnect the sensor.

   Note: Disconnecting the sensor wire from the ECM will generate an open circuit diagnostic code for the sensor. Troubleshoot the original diagnostic code. Delete the logged diagnostic codes when you are finished.

3. Turn the engine control to the ON position. The engine should be off.

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

Expected Result:

The supply voltage should reach 5.0 ± 0.2 VDC for all analog sensors and 8.0 ± 0.4 for all digital sensors.

Results:

• OK - The supply voltage is 5.0 ± 0.2 VDC for all analog sensors and 8.0 ± 0.4 for all digital sensors. The voltage is correct. Proceed to test step 8.

• Not OK - The supply voltage is not 5.0 ± 0.2 VDC for all analog sensors and 8.0 ± 0.4 for all digital sensors. The voltage is out of range. Proceed to test step 7.

Test Step 5. Check for a Short to the + Battery.

1. Turn the engine control 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 engine control to the STOP position. The engine should be off.

4. Measure the voltage on the ECM side of the sensor connector between pin B and the engine ground.

5. Measure the voltage on the ECM side of the sensor connector between pin C and the engine ground.

6. Turn the engine control to the OFF position.

Expected Result:

The voltage will measure 24 ± 3 VDC when a short to the + Battery is present.

Results:

• OK - The voltage measures 24 ± 3 VDC. A short to the + Battery is present.

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

  STOP

• Not OK - The voltage on pin B should measure 0 VDC. The voltage on pin C may measure approximately 6.5 VDC. The voltage on pin C is a pull up voltage. The ECM provides the pull up voltage to the signal input when the ECM senses an open circuit in the incoming input signal. Frequency sensors do not receive a pull up voltage. The sensor common and signal wire are not shorted to the + Battery. 6.

Test Step 6. Create a Short at the Sensor Connector.

1. Turn the engine control 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 engine control to the ON position. The engine should be off.

4. Check if the diagnostic code has changed from a CID-FMI of 03 to a CID-FMI of 04.

5. Turn the engine control to the OFF position.

6. Remove the wire short.

Expected Result:

The diagnostic code should change from a CID-FMI of 03 to a CID-FMI of 04.

Results:

• OK - The diagnostic code changed from a CID-FMI of 03 to a CID-FMI of 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 diagnostic code did not change from a CID-FMI of 03 to a CID-FMI of 04. The circuit indicates a open circuit diagnostic code. Proceed to test step 9.

Test Step 7. Check the Sensor Supply Voltage at the ECM.

1. Turn the engine control to the OFF position.

2. Disconnect the ECM connector P1.

3. Check the analog supply voltage. Remove wire 997-OR from ECM connector P1-36. Remove wire 993-BR from ECM connector P1-30.

4. Install jumper wires with socket terminals at each end into connector P1 after removing the wires.

5. Check the digital supply voltage. Remove wire A700-OR from ECM connector P1-35. Remove wire 998-BR from ECM connector P1-29.

6. Install jumper wires with socket terminals at each end into connector P1 after removing the wires.

7. Reconnect connector P1 to the ECM.

8. Turn the engine control to the ON position. The engine should be off.

9. Measure the analog voltage between the jumper wires that were installed at P1-36 and P1-30.

10. Measure the digital voltage between the jumper wires that were installed at P1-35 and P1-29.

11. Turn the engine control to the OFF position.

12. Remove the jumper wires and replace all wires.

Expected Result:

The analog supply voltage should be 5.0 ± 0.2 VDC. The digital supply voltage should be 8.0 ± 0.4 VDC.

Results:

• OK- Analog or Digital - The analog supply voltage is 5.0 ± 0.2 VDC. The digital supply voltage is 8.0 ± 0.4 VDC. The supply voltage at the ECM is correct. There is a problem in the wiring between the ECM and the sensor.

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

  STOP

• Not OK- Analog or Digital - The analog supply voltage is not 5.0 ± 0.2 VDC. The digital supply voltage is not 8.0 ± 0.4 VDC. The voltage at the ECM is not correct.

  Repair: Perform the diagnostic functional test Troubleshooting, "Electrical Power Supply".

  STOP

Test Step 8. Create an Open Circuit at the Sensor Connector.

1. Turn the engine control to the OFF position.

2. Turn the engine control to the ON position. The engine should be off.

3. Check if the diagnostic code has changed from a CID-FMI of 04 to a CID-FMI of 03 after disconnecting the sensor.

   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 sensor.

Expected Result:

The diagnostic code should change from a CID-FMI of 04 to a CID-FMI of 03.

Results:

• OK - The diagnostic code changed from a CID-FMI of 04 to a CID-FMI of 03. The open circuit was seen by the ECM. The wiring between the ECM and the sensor is okay.

  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 diagnostic code did not change from a CID-FMI of 04 to a CID-FMI of 03. The open circuit was not seen at the ECM. Proceed to test step 10.

Test Step 9. Install a Jumper Wire at the ECM Connector.

1. Connect the sensor.

2. Disconnect ECM connector P1.

3. Remove the sensor's signal wire from the ECM connector P1. Remove the sensor's common wire from the ECM connector P1.

4. Install a jumper wire with socket terminals at each end into ECM connector P1. Connect the jumper between the sensor signal wire and the sensor common.

   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. Delete the logged diagnostic codes when you are finished.

5. Reconnect the connector P1 to the ECM.

6. Turn the engine control to the ON position. The engine should be off.

7. Check if the diagnostic code has changed from a CID-FMI of 03 to a CID-FMI of 04 after installing the jumper.

8. Remove the jumper and reconnect all wires.

Expected Result:

The diagnostic code should change from a CID-FMI of 03 to a CID-FMI of 04.

Results:

• OK - The diagnostic code changed from a CID-FMI of 03 to a CID-FMI of 04. The ECM recognized the short at the ECM. There is a problem with the wiring between the ECM and the sensor.

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

  STOP

• Not OK - The diagnostic code did not change from a CID-FMI of 03 to a CID-FMI of 04. The ECM did not see the short at the ECM. Replace the ECM.

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

  STOP

Test Step 10. Create an Open at the ECM.

1. Turn the engine control to the OFF position.

2. Disconnect the sensor's signal wire from the ECM connector P1.

3. Turn the engine control to the ON position. The engine should be off.

4. The diagnostic code should change from a CID-FMI of 04 to a CID-FMI of 03 after the sensor signal wire is disconnected.

   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 diagnostic code should change from a CID-FMI of 04 to a CID-FMI of 03.

Results:

• OK - The diagnostic code changed from a CID-FMI of 04 to a CID-FMI of 03. 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 diagnostic code did not change from a CID-FMI of 04 to a CID-FMI of 03. The ECM did not recognize the short at the ECM.

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

  STOP

Test Step 11. Check the Fluid Levels.

1. Check the fuel level.

2. Check the engine oil level.

3. Check for any leaks.

Expected Result:

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

Results:

• OK - The fuel and engine oil levels are okay. Proceed to test step 12.

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

  Repair: If the engine 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 12. Compare the Pressure or Temperature to the Actual Pressure or Temperature.

1. Turn the engine control to the OFF position.

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

3. Turn the engine control to the ON position. The engine should be off.

4. Observe the temperature reading for the sensor. The Cat 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 sensor from the engine.

7. Reconnect the sensor.

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

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

10. Turn the engine control to the ON position. The engine should be off.

11. Observe the pressure reading for the sensor. The Cat 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 Cat ET and the pressure test kit.

Expected Result:

The Cat ET should show a constant pressure. The Cat ET should show a 5 ± 2 kPa (0.7 ± 0.3 psi) drop in pressure.

Results:

• OK - The Cat ET screen shows a constant pressure. The ET screen shows a 5 ± 2 kPa (0.7 ± 0.3 psi) drop in pressure.

  Repair: The sensor is working correctly. Reset the system and note any active diagnostic codes.

  STOP

• Not OK Analog - The Cat ET screen does not show a constant pressure. The Cat ET screen does not show a 5 ± 2 kPa (0.7 ± 0.3 psi) drop in pressure. The analog sensor is not producing the correct reading. Proceed to test step 13.

• Not OK Digital - The Cat ET screen does not show a constant pressure. The Cat ET screen does not show a 5 ± 2 kPa (0.7 ± 0.3 psi) drop in pressure. The digital sensor is not producing the correct reading. Proceed to test step 14.

• Vacuum Leak - The Cat ET screen does not show a constant pressure. The Cat ET screen does not show a 5 ± 2 kPa (0.7 ± 0.3 psi) drop in pressure. A vacuum leak is suspected.

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

  STOP

Test Step 13. Check the Analog Sensor's Signal Voltage at the Connector.

1. Turn the engine control to the ON position. The engine should be off.

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

Expected Result:

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

Results:

• OK - The sensor signal voltage is between 0.2 VDC and 4.8 VDC for analog sensors. The signal voltage is correct. Proceed to test step 17.

• Not OK - The sensor signal voltage is not between 0.2 VDC and 4.8 VDC for analog sensors. The signal voltage is not correct. Proceed to test step 15.

Test Step 14. Check the Digital Sensor's Signal Frequency and the Duty Cycle at the Sensor Connector.

1. Turn the engine control to the ON position. The engine should be off.

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

3. Turn the engine control 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 Cat ET should read 30 °C (86 °F). As the engine warms up the exhaust temperature should increase.

Results:

• OK - The digital sensor's duty cycle and frequency are correct. The digital output signal is correct. Proceed to test step 18.

• Not OK - The digital sensor's duty cycle and frequency are not correct. The digital output signal is not correct. Proceed to test step 15.

Test Step 15. Check for Shorts in the Wiring Harness

1. Turn the engine control to the OFF position.

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

3. Disconnect the sensor.

4. Measure the resistance between the sensor's signal wire and the sensor's voltage supply wire at the ECM connector.

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

6. Measure the resistance between the 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 16.

• 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 16. Check the Resistance through the Harness.

1. Disconnect the sensor connector.

2. Use a suitable piece of wire to connect pin A to pin C at the sensor connector.

3. Measure the resistance between the sensor signal wire and the sensor voltage supply at the ECM connector P1.

4. Use a suitable piece of wire to connect pin B to pin C at the sensor connector.

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

6. Turn the engine control to the OFF position.

7. Remove all wire shorts.

8. Reconnect all connectors.

Expected Result:

The resistance should be less than 10 Ohms through the harness.

Results:

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

• OK Digital - The resistance is less than 10 Ohms. Proceed to test step 18.

• 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 17. Check the Sensor's Analog Signal Voltage at the ECM Connector.

1. Turn the engine control to the ON position. The engine should be off.

2. Measure the sensor signal voltage between pin C and pin B at the ECM connector P1.

3. Observe the sensor reading on the status screen on the Cat ET.

4. Turn the engine control to the OFF position.

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

Expected Result:

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

Results:

• OK - The signal voltage for the analog sensors is between 0.2 VDC and 4.8 VDC for the analog sensor. The sensor voltage at the ECM is correct.

  Repair: 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 analog sensor. The sensor voltage at the ECM is not correct.

  Repair: Perform the diagnostic functional test Troubleshooting, "Analog Sensor Supply".

  STOP

• Intermittent Problem - The readings are not consistent.

  Repair: Perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

  STOP

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

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

  STOP

Test Step 18. Check the Digital Sensor's Signal Frequency and the Duty Cycle at the ECM.

1. Turn the engine control to the ON position. The engine should be off.

2. Measure the frequency and the duty cycle between pin C and pin B of the digital sensor at the ECM connector P1.

3. Start the engine.

4. Observe the sensor reading on the status screen on the Cat ET.

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

5. Turn the engine control 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 Cat ET should read 30 °C (86 °F). As the engine warms up the exhaust temperature should increase.

Results:

• OK - The digital sensor's duty cycle and frequency are correct.

  Repair: Reset the system and note any diagnostic codes.

  STOP

• Not OK - The digital sensor's duty cycle and frequency are not correct.

  Repair: Perform the diagnostic functional test Troubleshooting, "Digital Sensor Supply".

  STOP

• Intermittent Problem - The readings are not consistent.

  Repair: Perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

  STOP

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

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

  STOP