C32 Engine for D11T Track-Type Tractors Cooling Fan Override - Test Caterpillar

System Operation Description:

Use this procedure to troubleshoot the electrical system if a problem is suspected with the cooling fan bypass solenoid. Also, use this procedure if one of the diagnostic codes in Table 1 is active.

Illustration 1	g02340837
Location of the cooling fan bypass solenoid (1) Control Manifold Gp (2) Cooling fan bypass solenoid

The cooling fan bypass solenoid is used in areas with cold ambient temperatures. Under normal operating circumstances, the main cooling fan never turns off. The main cooling fan continues to operate at a minimum speed regardless of need. When the cooling fan bypass solenoid is activated, hydraulic flow to the fan motor will be bypassed. The result is no fan speed or slow fan speeds.

The following conditions must be met in order for the cooling fan bypass solenoid to activate.

• The temperature of the hydraulic oil must be between 50 °C (122 °F) and 100 °C (212 °F).

• The intake manifold air temperature must be less than a map-dependent value that is based on engine rpm.

• The coolant temperature must be below 88 °C (190 °F).

• The engine speed must be between 500 rpm and 1500 rpm.

Note: The ECM will only detect an open in the circuit if the cooling fan bypass solenoid is not activated. The ECM will only detect a short in the circuit if the cooling fan bypass solenoid has been activated.

Illustration 2	g01251396
Schematic for the cooling fan bypass solenoid

Test Step 1. Inspect the Electrical Connectors and the Wiring

1. Turn the keyswitch to the OFF position.

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Illustration 3	g01415758
Location of ECM connectors

2. Thoroughly inspect the J1/P1 ECM connectors. Also, thoroughly inspect all of the other connectors for the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

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Illustration 4	g01416322
Terminal locations at the P1 ECM connector for the cooling fan bypass solenoid (P1-18) Digital return (P1-19) Cooling fan bypass solenoid

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Illustration 5	g01155187
Terminal locations at the solenoid connector for the cooling fan bypass solenoid (Terminal 1) Power to the cooling fan bypass solenoid (Terminal 2) Digital 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 for 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 coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.

Results:

• OK - The harness and connectors 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 coupled.Verify that the repair eliminates the problem.

  STOP

Test Step 2. Check for Active Diagnostic Codes

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

2. Turn the keyswitch to the ON position.

3. 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.

4. Select diagnostic tests from Cat ET.

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

6. Activate the override for the cooling fan bypass solenoid.

7. 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.

8. Disable the override for the cooling fan bypass solenoid.

9. 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. Create an Open Circuit at the Harness Connector for the Cooling Fan Bypass

1. Turn the keyswitch to the OFF position.

2. Disconnect the connector for the cooling fan bypass solenoid.

3. Turn the keyswitch to the ON position.

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 override for the cooling fan bypass solenoid.

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 override for the cooling fan bypass solenoid.

Expected Result:

An open circuit diagnostic code -5 is now active for the cooling fan bypass 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 cooling fan bypass solenoid to the harness, but do not install the new cooling fan bypass solenoid. Verify that there are no active diagnostic codes for the cooling fan bypass solenoid. If there are no active diagnostic codes for the cooling fan bypass solenoid, permanently install the new cooling fan bypass solenoid. Clear any logged diagnostic codes.

  STOP

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

Test Step 4. Create a Short at the Harness Connector for the Cooling Fan Bypass Solenoid

1. Turn the keyswitch to the OFF position.

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

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

4. Turn the keyswitch to the ON position.

5. Select diagnostic tests from Cat ET.

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

7. Activate the override for the cooling fan bypass solenoid.

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 override for the cooling fan bypass solenoid. Remove the jumper wire.

Expected Result:

A short circuit diagnostic code -6 is active when the jumper wire is installed.

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 cooling fan bypass solenoid to the harness, but do not install the new cooling fan bypass solenoid. Verify that there are no active diagnostic codes for the cooling fan bypass solenoid. If there are no active diagnostic codes for the cooling fan bypass solenoid, permanently install the new cooling fan bypass 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 cooling fan bypass solenoid. Proceed to Test Step 5.

Test Step 5. Check the Operation of the ECM

1. Disconnect the J1/P1 ECM connector.

2. Fabricate a jumper wire that is long enough to create a short between the ECM connector and engine ground. Crimp a connector socket to one end of the jumper wire.

3. Remove the wire from terminal location P1-43 (cooling fan bypass solenoid) at the ECM connector. Install the jumper wire into this terminal location.

4. Connect the J1/P1 ECM connector.

5. Create an open at the ECM:

   1. Turn the keyswitch to the ON position.

      Do not allow the loose end of the jumper wire to connect to any other wires 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 override for the cooling fan bypass solenoid.

   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 override for the cooling fan bypass solenoid.

6. Create a short at the ECM:

   1. Create a short between the jumper wire for the solenoid and engine ground.

   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 override for the cooling fan bypass solenoid.

   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 override for the cooling fan bypass solenoid.

   8. Turn the keyswitch to the OFF position.

7. Restore all wiring to the original configuration.

Expected Result:

An open circuit diagnostic code -5 is active when the jumper wire creates an open circuit. A short circuit diagnostic code -6 is active when the jumper wire for the solenoid is shorted to engine ground.

Results:

• OK - An open circuit diagnostic code -5 is active when the jumper wire creates an open circuit. A short circuit diagnostic code -6 is active when the jumper wire for the solenoid is shorted to engine ground.

  Repair: The ECM is operating properly. The problem is in the harness wiring between the ECM and the connector for the cooling fan bypass 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 jumper wire creates an open circuit. The short circuit diagnostic code -6 is not active when the jumper wire is shorted to engine ground.

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

  STOP