3512B Marine Auxiliary Engine Caterpillar

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

The ECM performs an automatic calibration of all the analog pressure 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 Compartment Pressure Sensor and an acceptable offset pressure range.

Illustration 1	g00858628
Primary ECM

Illustration 2	g00860212
Secondary ECM

Test Step 1. Check for Connector Damage.

1. Turn the circuit breaker for the battery to the OFF/RESET position.

2. Turn the ECS to the OFF position.

3. Check the connectors and wiring for the following problems: damage, corrosion, abrasion and incorrect attachment.

Expected Result:

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

Results:

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

• Not OK - The wiring and connectors need repair.

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

  Stop.

Test Step 2. Check for Active Diagnostic Codes.

1. Connect the Caterpillar Electronic Technician (ET) to the service tool connector.

2. Turn the ECS to the STOP position. The engine should be OFF.

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

Expected Result:

Determine the failure mode identifier (FMI). Determine if diagnostic codes 262-03 or 262-04 are present. Determine if diagnostic codes 263-03 or 263-04 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, 02 or 08 - A diagnostic code with a FMI of 00, 02 or 08 is present. Proceed to test step 8.

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

Test Step 3. Check the Voltage at the Sensor Connector.

1. Turn the ECS to the STOP position.

2. Measure the voltage on the sensor side of the wiring harness. Measure the voltage between pin A and pin B for the suspect sensor.

Expected Result:

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

Results:

• OK - The voltage is correct. Proceed to test step 5.

• Not OK - The voltage is out of range. Proceed to test step 6.

Test Step 4. Check the Voltage at the Sensor Connector.

1. Turn the ECS to the STOP position.

2. Measure the voltage on the ECM side of the wiring harness. Measure the voltage between pin A and pin B for the suspect sensor.

Expected Result:

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

Results:

• OK - The voltage is correct. Proceed to test step 7.

• Not OK - The voltage is out of range. Proceed to test step 6.

Test Step 5. Create a Short at the Sensor Connector.

1. Turn the ECS to the OFF/RESET position.

2. Disconnect the suspect sensor.

3. Use a wire with socket terminals at each end. Connect pin B and pin C at the suspect sensor connector.

4. Turn the ECS to the ON position. The engine should be OFF.

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

6. Turn the ECS to the OFF/RESET position.

7. Remove the wire short.

Expected Result:

The CID-FMI should change from 03 to 04.

Results:

• OK - 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 circuit indicates an open circuit diagnostic code. Proceed to test step 9.

Test Step 6. Check the Voltage at the ECM.

1. Turn the ECS to the OFF/RESET position.

2. Disconnect the primary ECM connector J1/P1.

3. Remove the digital supply line on pin P1-35 of the ECM. Install a jumper into the socket for P1-35.

   Note: Disconnecting the common wire to a sensor will cause several sensor diagnostic codes to become active. Troubleshoot the original code. Reset the system. Delete the logged diagnostic codes when your are finished.

4. Remove the digital return line on pin P1-29 of the ECM. Install a jumper into the socket for P1-29.

5. Remove the analog supply line on pin P1-36 of the ECM. Install a jumper into the socket for P1-36.

6. Remove the analog return line on pin P1-30 of the ECM. Install a jumper into the socket for P1-30.

7. Reconnect the primary ECM connector J1/P1.

8. Turn the ECS to the STOP position. The engine should be OFF.

9. Measure the analog voltage between the wire jumpers in P1-36 and P1-30.

10. Measure the digital voltage between the wire jumpers in P1-35 and P1-29.

11. Turn the ECS to the OFF/RESET position.

12. Remove all of the test wires. Reconnect all wiring and connectors.

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 - The analog supply voltage is 5.0 ± 0.2 VDC. The digital supply voltage is 8.0 ± 0.4 VDC.

  Repair: There is a problem in the wiring harness between the ECM and the sensor connector. Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

• Not OK - The analog supply voltage is not 5.0 ± 0.2 VDC.

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

  Stop.

• Not OK - The digital supply voltage is not 8.0 ± 0.4 VDC.

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

  Stop.

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

1. Turn the ECS to the OFF/RESET position.

2. Disconnect the suspect sensor.

3. Turn the ECS to the STOP position. The engine should be OFF.

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

   Note: Disconnecting the Compartment 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 is disconnected.

Results:

• OK - The CID-FMI changed from 04 to 03 when the sensor was disconnected.

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

  Stop.

• Not OK - The CID-FMI did not change from 04 to 03 when the sensor was disconnected. Proceed to test step 10.

Test Step 8. Compare the Pressure or Temperature to the Actual Pressure or Temperature.

1. Turn the ECS to the STOP position.

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

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

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

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

5. Remove the suspect sensor from the engine.

6. Connect the suspect sensor to the sensor connector.

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

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

9. Turn the ECS to the STOP position. The engine should be OFF.

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

11. 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.

12. Compare the readings on the Cat ET and the pressure test kit.

Expected Result:

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

Results:

• OK - The sensor is working correctly.

  Repair: Reset the system and note any active diagnostic codes.

  Stop.

• Not OK - The Cat ET did not show constant pressure. Proceed to test step 11.

• Not OK - Vacuum Leak

  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 9. Install a Jumper Wire at the ECM.

1. Connect the suspect sensor.

2. Remove the suspect sensor signal wire from the ECM. Remove the suspect ground wire from the ECM.

   Note: Disconnecting the common wire to a sensor will cause several sensor diagnostic codes to become active. Troubleshoot the original code. Reset the system. Delete the logged diagnostic codes when your are finished.

3. Use a wire with socket terminals at each end. Connect the jumper wire at the ECM between the sensor signal and the engine ground.

4. Turn the ECS to the STOP position. The engine should be OFF.

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

Expected Result:

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

Results:

• OK - The diagnostic code changed from an FMI of 03 to an FMI of 04.

  Repair: There is a problem with the wiring between the ECM and the suspect sensor. Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

• Not OK - Replace the ECM.

  Repair: Perform the diagnostic procedure Troubleshooting, "Replacing the ECM".

  Stop.

Test Step 10. Create an Open at the ECM.

1. Turn the ECS to the STOP position.

2. Disconnect the suspect sensor signal wire from the ECM connector.

3. Turn the ECS to the STOP position. The engine should be OFF.

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

   Note: Disconnecting the Compartment 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 diagnostic code has changed from a FMI of 04 to an FMI of 03.

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

  Stop.

• Not OK - Replace the ECM.

  Repair: Perform the diagnostic procedure Troubleshooting, "Replacing the ECM".

  Stop.

Test Step 11. Check the Voltage at the Sensor Connector.

1. Turn the ECS to the STOP position.

2. Measure the analog sensor voltage. Turn the ECS to the ON position. The engine should be OFF.

3. Measure the voltage between pin C and pin B.

4. Measure the digital sensor voltage. Turn the ECS to the OFF/RESET position.

5. Turn the ECS to the STOP position. The engine should be OFF.

6. Measure the frequency and the duty cycle between pin C and pin B.

Expected Result:

The signal voltage should be between 0.2 VDC and 4.5 VDC for all analog sensors.

The frequency reading should be between 150 Hz and 1000 Hz for all digital sensors.

When the temperature is below 49 °C (120 °F), the duty cycle should be between 10% 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%.

When the temperature is above 851 °C (1564 °F), the duty cycle should be between 80% to 90%.

Results:

• OK - The signal voltage is within the acceptable range. The frequency reading is within the acceptable range. The duty cycle is within the acceptable range. Proceed to test step 12.

• Not OK - The frequency reading is not within the acceptable range. The duty cycle is not within the acceptable range. Proceed to test step 13.

Test Step 12. Check for Shorts inthe Wiring Harness

1. Turn the ECS to the OFF/RESET position.

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

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.

6. Reconnect all connectors.

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 14.

• 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 13. Check the Signal Frequency and the Duty Cycle at the Sensor Connector.

1. Turn the ECS to the OFF/RESET position.

2. Remove the wire from pin C.

3. Turn the ECS to the STOP position.

4. Measure the frequency and the duty cycle from the sensor signal wire (pin C) with reference to the sensor return line (pin B).

5. Turn the ECS to the OFF/RESET position.

Expected Result:

The frequency reading should be between 150 Hz and 1000 Hz.

When the temperature is below 49 °C (120 °F), the duty cycle should be between 10% 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%.

When the temperature is above 851 °C (1564 °F), the duty cycle should be between 80% to 90%.

Results:

• OK - The frequency reading is within the acceptable range. The duty cycle is within the acceptable range. Proceed to test step 12.

• Not OK - The frequency reading is not within the acceptable range. The duty cycle is not within the acceptable range.

  Repair: Temporarily replace the sensor. Verify that the repair eliminates the problem. Replace the faulty sensor.

  Stop.

Test Step 14. Check the Resistance through the Harness.

1. Disconnect ECM connectors J1/P1 and J2/P2. Disconnect the suspect sensors.

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

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

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

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

6. Remove all wire shorts.

7. Reconnect all connectors.

Expected Result:

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

Results:

• OK - The resistance is less than 10 Ohms through the harness.

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

  Stop.

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

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

  Stop.

Test Step 15. Check the Voltage at the ECM.

1. Turn the ECS to the OFF/RESET position.

2. Turn the ECS to the STOP position. The engine should be OFF.

3. Measure the analog voltage between the suspect sensor signal voltage and the sensor return line at the ECM connector P1.

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

5. Turn the ECS to the OFF/RESET position.

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

6. Turn the ECS to the OFF/RESET position.

7. Turn the ECS to the STOP position. The engine should be OFF.

8. Measure the frequency and the duty cycle between the digital suspect sensor signal and the sensor return line at the ECM connector P1.

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

   Note: The status screen on the Cat ET displays INVALID DATA when the ECM reads an signal that is out of range.

10. Turn the ECS to the OFF/RESET position.

Expected Result:

The signal voltage for the analog sensors should be between 0.2 VDC and 0.6 VDC for the suspect analog sensor.

The frequency reading should be between 150 Hz and 1000 Hz.

When the temperature is below 49 °C (120 °F), the duty cycle should be between 10% 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%.

When the temperature is above 851 °C (1564 °F), the duty cycle should be between 80% to 90%.

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

Results:

• OK - The sensor is working correctly.

  Repair: Reset the system and note any diagnostic codes.

  Stop.

• Not OK - The analog voltage is not correct.

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

  Stop.

• Not OK - The frequency reading is not between 150 Hz and 1000 Hz.

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

  Stop.

• Not OK - Intermittent Problem

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

  Stop.

• Not OK - Invalid Data

  Repair: Perform the diagnostic procedure Troubleshooting, "Replacing the ECM".

  Stop.