3512B Marine Auxiliary Engine 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	g00904409

Note: The Engine Control Switch (ECS) is mounted within an instrument panel that is located on the right side of the engine. The ECS is locked into the AUTO position with a pin. The pin must be removed in order to perform this test. After performing this test, ensure that the ECS is placed in the AUTO position and that the locking pin has been reinstalled.

Test Step 1. Check for Connector Damage.

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

2. Turn the battery disconnect switch 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 for pinch points.

Expected Result:

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

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. Connect the Caterpillar Electronic Technician (ET) to the ECM through the J60/P60 service tool connector.

2. Turn the battery disconnect switch to the ON position.

3. Turn the ECS to the STOP 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 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 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 of 08 is present. Proceed to test step 11.

• 262-03 or 262-04 Active Code - A diagnostic code of 262-03 or of 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 Sensor Supply Voltage at the Sensor Connector if the Diagnostic Code FMI-03 is Present.

1. Turn the ECS to the OFF/RESET 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 ECS to the STOP position. The engine should be off.

4. Measure the voltage on the ECM side of the sensor connector 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 5.0 ± 0.2 VDC for all analog sensors and 8.0 ± 0.4 VDC for all digital sensors. Proceed to test step 5.

• Not OK - The voltage is not 5.0 ± 0.2 VDC for all analog sensors and 8.0 ± 0.4 VDC for all digital sensors. 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 ECS to the OFF/RESET 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 ECS to the STOP position. The engine should be off.

4. Measure the voltage on the ECM side of the sensor connector 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 5.0 ± 0.2 VDC for all analog sensors and 8.0 ± 0.4 VDC for all digital sensors. Proceed to test step 8.

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

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

1. Turn the ECS to the OFF/RESET 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 ECS 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 ECS to the OFF/RESET 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. Proceed to test step 6.

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

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

2. Use a wire jumper to connect pin B and pin C together on the sensor connector.

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

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

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

6. Remove the wire jumper.

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 9.

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

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

2. Check the analog supply voltage by removing wires P1-36 (997-OR) and P1-30 (993-BR) from ECM connector P1. Install a wire jumper into the sockets for P1-36 and for P1-30.

   Check the digital supply voltage by removing wires P1-35 (A700-OR) and P1-29 (998-BR) from ECM connector P1. Install a wire jumper into the sockets for P1-35 and for P1-29.

   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.

3. Reconnect ECM connector J1/P1.

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

5. Measure the analog voltage between P1-36 and P1-30 at the wire jumpers.

6. Measure the digital voltage between P1-35 and P1-29 at the wire jumpers.

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

8. Remove the wire jumpers and replace all wires. Reconnect ECM connector J1/P1.

Expected Result:

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

Results:

• OK - Analog or Digital - The supply voltage is 5.0 ± 0.2 VDC for all analog sensors and 8.0 ± 0.4 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 ± 0.2 VDC for all analog sensors and 8.0 ± 0.4 for all digital sensors. 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 ECS to the OFF/RESET position.

2. Leave the sensor disconnected.

3. Wait for a period of 15 seconds.

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

5. 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. Delete the logged diagnostic codes when you are finished.

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

7. 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 10.

Test Step 9. Create a Short at the ECM Connector.

1. Connect the suspect sensor.

2. Remove the suspect sensor's signal wire from ECM connector P1 or P2. Install a wire jumper into the socket for the signal wire.

3. Use a jumper to create a short between the wire jumper and sensor's common wire.

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.

6. Turn the ECS to the OFF/RESET position. The engine should be off.

7. Remove the wire jumper and replace the signal wire. Reconnect ECM connector J1/P1 and/or J2/P2.

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.

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

  Stop.

Test Step 10. Create an Open at the ECM.

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

2. Remove the suspect sensor signal wire from J1/P1 or J2/P2.

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

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

6. Replace the signal wire and reconnect ECM connector J1/P1 or J2/P2.

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

  Stop.

Test Step 11. 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 12.

• 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 12. Compare the Pressure or Temperature to the Actual Pressure or Temperature.

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

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

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

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

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

6. Remove the suspect sensor from the engine.

7. Reconnect the suspect sensor.

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

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

10. Turn the ECS to the STOP position. The engine should be off.

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

Results:

• OK - The correct temperature is shown on the Cat ET. A constant pressure is shown on the Cat ET. A 5 ± 2 kPa (0.7 ± 0.3 psi) drop in pressure is shown on the Cat ET when the vacuum is applied. The sensor is working correctly. Reset the system and note any active diagnostic codes. Stop.

• Not OK - Analog - A constant pressure is not shown on the Cat ET. A 5 ± 2 kPa (0.7 ± 0.3 psi) drop in pressure is not shown on the Cat ET while the vacuum is being applied. An analog sensor is not producing the correct reading. Proceed to test step 13.

• Not OK - Digital - The correct temperature is not shown on the Cat ET. A digital sensor is not producing the correct reading. Proceed to test step 14.

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

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

2. Remove the sensor's signal wire from pin C of the sensor connector.

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

4. Measure the sensor signal voltage between the sensor's signal wire and pin B at the sensor connector.

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

6. Replace the sensor signal wire 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 17.

• Not OK - The signal voltage is not between 0.2 VDC and 4.8 VDC for analog sensors. 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 ECS to the OFF/RESET position.

2. Remove the sensor's signal wire from pin C of the sensor connector.

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

4. Measure the frequency and the duty cycle between the sensor's signal wire and pin B of the suspect digital sensor at the sensor connector.

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

6. Replace the sensor's signal wire and reconnect the sensor.

Expected Result:

The frequency reading should be approximately 500 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 18.

• Not OK - The frequency and the duty cycle are not correct. Proceed to test step 15.

Test Step 15. Check for Shorts in the Wiring Harness.

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

2. Measure the resistance between the sensor signal wire and engine ground.

3. Measure the resistance between the sensor common and engine ground.

4. Measure the resistance between the sensor supply and engine ground at the ECM connector.

5. Reconnect all connectors and all sensors.

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 suspect sensor connector.

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

3. Measure the resistance between the sensor signal wire and the sensor voltage supply at the ECM connector P1 or P2.

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

5. Measure the resistance between the sensor signal and the sensor common at the ECM connector P1 or P2.

6. Use a suitable piece of wire to connect pin A to pin B.

7. Measure the resistance between the sensor supply and the sensor common at the ECM connector P1 or P2.

8. Remove all wire shorts.

9. Reconnect all connectors and all sensors.

Expected Result:

The resistance should be less than 10 Ohms.

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 Analog Sensor's Signal Voltage at the ECM.

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

2. Measure the sensor signal voltage between pin C and pin B at the ECM connector P1 or P2.

3. 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.

4. Turn the ECS to the OFF/RESET 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. The Cat ET screen displays the correct information.

  Repair: There may be an intermittent problem. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

  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: Repair the connectors and/or wiring between the ECM connector and the sensor.

  Stop.

• ABNORMAL SIGNAL - The status screen on the Cat ET displays "ABNORMAL SIGNAL". 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.

  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 ECS to the STOP position. The engine should be off.

2. Measure the frequency and the duty cycle between pin C and pin B at the ECM connector P1 or P2.

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 ECS to the OFF/RESET position.

Expected Result:

The frequency reading should be approximately 500 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 voltage at the ECM is correct.

  Repair: There may be an intermittent problem. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

  Stop.

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

  Repair: Repair the connectors and/or wiring between the ECM and the sensor.

  Stop.

• ABNORMAL SIGNAL - The digital sensor voltage at the ECM is correct. 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.