3408E and 3412E Engines for Caterpillar Built Machines Cooling Fan Control - Test Caterpillar

System Operation Description:

Use this procedure to troubleshoot the electrical system if a problem is suspected with the engine fan control solenoid or if one of the diagnostic codes in Table 1 is active.

The ECM controls the speed of the engine cooling fan in order to provide the following benefits:

• Increased productivity

• Reduced noise

• Improved fuel economy

• Reduced overcooling of the engine

The ECM monitors engine coolant temperature and intake manifold air temperature in order to determine the correct speed for the engine cooling fan.

The ECM controls the speed of the fan by controlling the current to the engine fan control solenoid. The engine fan control solenoid limits the amount of pressure to the fan pump by allowing oil to bypass the fan pump. The fan pump drives the fan. When the ECM outputs minimum current to the engine fan control solenoid less oil is bypassed and the fan pump will drive the fan at a higher rpm. When the ECM outputs maximum current to the engine fan control solenoid more oil is bypassed and the fan pump will drive the fan at a lower rpm.

If the ECM detects a system fault, the ECM disables the fan control.

An override is available with AVSpare Electronic Technician (ET). This allows the fan to be manually changed from the minimum to the maximum possible rpm.

Illustration 1	g01393057
Schematic for the engine fan control solenoid

Test Step 1. Inspect the Electrical Connectors and the Wiring

1. Remove electrical power from the ECM.

Show/hide table



Illustration 2	g01139425
ECM (1) J1/P1 connectors (2) J2/P2 connectors

2. Thoroughly inspect connectors (1) and (2). Inspect all of the other connectors that are in the circuit for the engine fan control solenoid. Refer to Troubleshooting, "Electrical Connectors - Inspect".

Show/hide table



Illustration 3	g01891557
P2 ECM connector (P2-19) Engine fan control solenoid (P2-7) Solenoid return

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

4. Check the allen head screw on each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.

5. 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 are free of corrosion, of abrasion, and of pinch points.

Results:

• OK - The harness and wiring appear to be OK. Proceed to Test Step 2.

• Not OK - There is a problem in the connectors and/or wiring.

  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. Remove electrical power from the ECM.

2. Connect Cat ET to the service tool connector.

3. Restore electrical power to the ECM.

4. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

5. Select diagnostic tests from Cat ET.

6. Select the "Override Parameters" screen on Cat ET.

7. Activate the fan override.

8. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 30 seconds in order for the diagnostic code to become active.

9. Disable the fan override.

10. Determine if the problem is related to an open circuit diagnostic code -5 or a short circuit diagnostic code -6.

Expected Result:

No diagnostic codes are active.

Results:

• OK - No diagnostic codes are active.

  Repair: The problem may have been related to a faulty connection in the harness. Carefully inspect the connectors and wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

• Not OK - A short circuit diagnostic code -6 is active at this time. Proceed to Test Step 3.

• Not OK - An open circuit diagnostic code -5 is active at this time. Proceed to Test Step 4.

Test Step 3. Disconnect the Connector for the Engine Fan Control Solenoid in Order to Create an Open Circuit

1. Remove electrical power from the ECM.

2. Disconnect the connector for the engine fan control solenoid.

3. Restore electrical power to the ECM.

4. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

5. Select diagnostic tests from Cat ET.

6. Select the "Override Parameters" screen on Cat ET.

7. Activate the fan override.

8. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 30 seconds in order for the diagnostic code to become active.

9. Disable the fan override.

Expected Result:

An open circuit diagnostic code -5 is now active for the engine fan control solenoid.

Results:

• OK - A short circuit diagnostic code -6 was active before disconnecting the connector. An open circuit diagnostic code -5 became active after disconnecting the connector.

  Repair: Temporarily connect a new engine fan control solenoid to the harness, but do not install the new engine fan control solenoid. Verify that there are no active diagnostic codes for the engine fan control solenoid. If there are no active diagnostic codes for the engine fan control solenoid, permanently install the new engine fan control solenoid. Clear any logged diagnostic codes.

  STOP

• Not OK - A short circuit diagnostic code -6 remains active when the connector for the engine fan control solenoid is disconnected. There is a short circuit between the harness connector for the engine fan control solenoid and the ECM. Proceed to Test Step 5.

Test Step 4. Create a Short at the Connector for the Engine Fan Control Solenoid

1. Remove electrical power from the ECM.

2. Fabricate a jumper wire that is long enough to create a short between the terminals of the connector for the engine fan control solenoid. Crimp connector pins to each end of the jumper wire.

3. Install the jumper wire between terminal 1 (engine fan control solenoid) and terminal 2 (solenoid return) on the harness side of the connector.

4. Restore electrical power to the ECM.

5. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

6. Select diagnostic tests from Cat ET.

7. Select the "Override Parameters" screen on Cat ET.

8. Activate the fan override.

9. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 30 seconds in order for the diagnostic code to become active.

10. Disable the fan override. Remove the jumper wire.

Expected Result:

A short circuit diagnostic code -6 is active when the jumper wire is installed. An open circuit diagnostic code -5 is active when the jumper wire is removed.

Results:

• OK - A short circuit diagnostic code -6 is active when the jumper wire is installed. An open circuit diagnostic code -5 is active when the jumper wire is removed.

  Repair: The engine harness and the ECM are OK. Temporarily connect a new engine fan control solenoid to the harness, but do not install the new engine fan control solenoid. Verify that there are no active diagnostic codes for the engine fan control solenoid. If there are no active diagnostic codes for the engine fan control solenoid, permanently install the new engine fan control solenoid. Clear any logged diagnostic codes.

  STOP

• Not OK - The open circuit diagnostic code -5 remains active with the jumper in place. The open circuit is between the ECM and the connector for the engine fan control solenoid. There may be a problem with the ECM. Proceed to Test Step 5.

Test Step 5. Check the Operation of the ECM

1. Remove electrical power from the ECM.

2. Disconnect the J2/P2 ECM connector.

3. Fabricate two jumper wires that are long enough to create a short between the two terminal of the ECM connector. Crimp connector sockets to one end of each of the jumper wires.

4. Remove the wire from terminal location P2-19 (engine fan control solenoid) at the ECM connector. Install one of the jumper wires into this terminal location.

5. Remove the wire from terminal location P2-7 (solenoid return) at the ECM connector. Install the other jumper wire into this terminal location.

6. Connect the J2/P2 ECM connector.

7. Create an open at the ECM:

   1. Restore electrical power to the ECM.

      In order to ensure that an open circuit condition exists, do not allow the loose ends of the jumper wires to connect to each other or to engine ground.

   2. Monitor the "Active Diagnostic Code" screen on Cat ET. Check and record any active diagnostic codes.

      Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

   3. Select diagnostic tests from Cat ET.

   4. Select the "Override Parameters" screen on Cat ET.

   5. Activate the fan override.

   6. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

      Note: Wait at least 30 seconds in order for the diagnostic code to become active.

   7. Disable the fan override.

8. Create a Short at the ECM:

   1. Create a short between the jumper wires for the engine fan control solenoid at the ECM connector.

   2. Monitor the "Active Diagnostic Code" screen on Cat ET. Wait at least 30 seconds for activation of the code.

   3. Select diagnostic tests from Cat ET.

   4. Select the "Override Parameters" screen on Cat ET.

   5. Activate the fan override.

   6. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

      Note: Wait at least 30 seconds in order for the diagnostic code to become active.

   7. Disable the fan override.

   8. Remove electrical power from the ECM.

9. Restore all wiring to the original configuration.

Expected Result:

An open circuit diagnostic code -5 is active when the jumper wires create an open circuit. A short circuit diagnostic code -6 is active when the jumper wires for the engine fan control solenoid are shorted together.

Results:

• OK - An open circuit diagnostic code -5 is active when the jumper wires create an open circuit. A short circuit diagnostic code -6 is active when the jumper wires are shorted together.

  Repair: The ECM is operating properly. The problem is in the harness wiring between the ECM and the connector for the engine fan control solenoid. There may be a problem in one of the connectors. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

• Not OK - One of the following conditions exists: The open circuit diagnostic code -5 is not active when the wires create an open circuit. The short circuit diagnostic code -6 is not active when the wire jumpers are shorted together.

  Repair: Replace the ECM. Refer to Troubleshooting, "ECM - Replace". Verify that the problem is resolved.

  STOP