C18 Marine Auxiliary Engines Caterpillar

The Electronic Control Module (ECM) supplies a regulated voltage of 5.0 ± 0.5 VDC to the following sensors:

• Fuel pressure sensor

• Engine oil pressure sensor

• Atmospheric pressure sensor

• Turbocharger outlet pressure sensor

Illustration 1	g01044553

Illustration 2	g01045415

Test Step 1. Inspect Electrical Connectors and Wiring

1. Turn the keyswitch to the OFF position.

2. Thoroughly inspect the J2/P2 ECM connector. Thoroughly inspect the connectors for each analog sensor.

   Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

3. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the analog sensor supply:

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

5. Check the harness and wiring for abrasion and pinch points from the sensors back to the ECM.

Expected Result:

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

Results:

• OK - The harness and connectors appear to be 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. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.

  Stop.

Test Step 2. Check for Active Diagnostic Codes

1. Connect the electronic service tool to the service tool connector.

2. Turn the keyswitch to the ON position.

3. Monitor the active diagnostic code screen on the electronic service tool. Check and record any active diagnostic codes.

   Note: Wait at least 15 seconds in order for the diagnostic codes to become active.

Expected Result:

One of the following diagnostic codes is active:

• 262-03

• 262-04

Results:

• OK - A 262-03 or 262-04 diagnostic code is active. Proceed to Test Step 3.

• Not OK - A 262-03 or 262-04 diagnostic code is logged. Proceed to Test Step 5.

Test Step 3. Disconnect the +5 V Pressure Sensors while you Monitor the Active Diagnostic Codes

1. Disconnect the following sensors one at a time:
   • Fuel pressure sensor J209/P209

   • Engine oil pressure sensor J201/P201

   • Atmospheric pressure sensor J203/P203

   • Turbocharger outlet pressure sensor J200/P200

2. Wait for 15 seconds after each pressure sensor is disconnected. Check for an active diagnostic code on the electronic service tool.

Expected Result:

The original 262-03 or 262-04 diagnostic code remains active.

Results:

• OK - A 262-03 or 262-04 diagnostic code is still active. Leave the sensors disconnected. Proceed to Test Step 4.

• Not OK - A 262-03 or 262-04 diagnostic code deactivates. The diagnostic codes are not active after a specific sensor is disconnected.

  Repair: Reconnect the sensor that is suspected of causing the problem. If the problem returns after the reconnection of the sensor, disconnect the sensor. If the problem disappears after the disconnection of the sensor, replace the sensor.Clear all diagnostic codes. Verify that the repair eliminates the problem.

  Stop.

Test Step 4. Open the +5 V Supply at the ECM

1. Turn the keyswitch to the OFF position.

2. Disconnect ECM connector J2/P2.

   1. Remove the wire 997-OR from ECM connector P2:2 (Analog Sensor Power +5V).

   2. Reconnect ECM connector J2/P2.

3. Turn the keyswitch to the ON position.

4. Check for active diagnostic codes on the electronic service tool.

5. Turn the keyswitch to the OFF position.

6. Replace all wires to the original configuration.

Expected Result:

A 262-03 or 262-04 code is no longer active.

Results:

• OK - A 262-03 or 262-04 code is no longer active. The ECM is responding correctly. Reconnect the wire. Proceed to Test Step 5.

• Not OK - A 262-03 or 262-04 code is still active. The ECM is not responding correctly.

  Repair: Verify your results before replacing the ECM. Refer to Troubleshooting, "Replacing the ECM" before you replace the ECM.

  Stop.

Test Step 5. Check the +5 V Supply Wire for a Short to Ground or a Short to Another Wire in the Harness

1. Turn the keyswitch to the OFF position.

2. Disconnect the J2/P2 ECM connector. Verify that all of the following analog sensors that are attached to the ECM connectors are disconnected:
   • Fuel pressure sensor J209/P209

   • Engine oil pressure sensor J201/P201

   • Atmospheric pressure sensor J203/P203

   • Turbocharger outlet pressure sensor J200/P200

Note: Wiggle the harness during the following measurements in order to reveal any intermittent short condition.

3. Measure the resistance from the ECM connector P2:2 (Analog Sensor Power +5V) to every pin on ECM connector P2.

   1. Measure the resistance from the ECM connector P2:2 to the ECM ground strap.

Expected Result:

Each resistance measurement is more than 20,000 Ohms.

Results:

• OK - The resistance check does not indicate a short in the engine harness or a short to ground. Ensure that the engine harness is connected to the ECM and that all of the sensors are reconnected.

  Repair: The problem may be intermittent. If the problem is intermittent, refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".

  Stop.

• Not OK - A resistance measurement is less than 20,000 Ohms. The +5 V line is shorted in the engine harness or the +5 V line is shorted to engine ground.

  Repair: Repair the wire or replace the wire. Clear all logged diagnostic codes. Verify that the repair eliminates the problem.

  Stop.