3406E, C-10, C-12, C-15, C-16 and C-18 On-highway Engines Caterpillar

Use this procedure under the following situation:

The cooling fan (Output 5) or the A/C high pressure switch (Input 11) is suspected of incorrect operation.

Note: Not all vehicle manufacturers, or all trucks for a manufacturer use the Caterpillar cooling fan circuit. Prior to troubleshooting, determine if the vehicle is using the ECM cooling fan circuit.

Check the following items in order to determine if a vehicle is using the ECM cooling fan circuit:

• The "Fan Control Type" parameter must be programmed to "On/Off", "Three-Speed Fan", or "Variable Speed Fan Option S". The Caterpillar factory default is None.

• A wire is present in the ECM vehicle harness connector J1/P1:11 which is Output 5 (Cooling Fan Solenoid). This occurs if an "On/Off" type of fan is used.

• A wire is present in the vehicle harness connector J1/P1:11 which is Output 5 (Slip Solenoid). A wire is also present in the vehicle harness connector J1/P1:13 which is Output 4 (Brake Solenoid). This occurs if a Three-Speed Fan is used.

• Perform the Special Test for the "On/Off Cooling Fan" or the special tests for the "Three-Speed Fan". Access each menu in the order that follows: "Diagnostics", "Diagnostic Tests" and "Special Test". Activating and then deactivating the circuit should cause the air solenoid to click if the circuit is working properly.

The following background information is related to this procedure:

Cooling Fan

The signal for the cooling fan is provided by the ECM in order to control the cooling fan. An input from one of the following items may cause the fan to turn on:

• Engine Coolant Temperature Sensor

• Intake Manifold Air Temperature Sensor

• Engine Retarder Switches

• PTO On/Off Switch

• OEM installed A/C High Pressure Switch

• Fan Override Switch

The control unit for the A/C may be connected to the A/C high pressure switch (Input 11) instead of a switch.

The output for the cooling fan is intended to connect directly to the circuit for the cooling fan solenoid. The solenoid and clutch configuration must be selected in order for the ECM output to turn the fan "Off". The fan will remain on for a minimum of 30 seconds. The fan will not remain on for 30 seconds during engine start-up. The fan will not remain on for 30 seconds if the "A/C Pressure Switch Fan On Time" is programmed to less than 30 seconds. During engine start-up, the ECM will keep the fan on for two seconds after the engine has reached the programmed low idle (600 to 750 rpm). The fan will be on continuously if the electrical circuit to the cooling fan air solenoid valve has an open circuit or if the ECM fan relay circuit is opened.

Cooling Fan On Conditions (On/Off Fan)

The ECM will turn on the cooling fan, if any of the following conditions are met:

• Engine speed is less than 2250 rpm.

• The engine is not running.

• The engine is cranking.

• The temperature of the coolant temperature sensor for the C-10 and the C-12 engines is greater than 96 °C (205 °F).

• The temperature of the coolant temperature sensor for the 3406E, C-15, C-16 and C-18 engines is greater than 102 °C (216 °F).

• Active diagnostic code for the coolant temperature sensor

• The intake manifold air temperature is greater than 87 °C (189 °F).

• The intake manifold air temperature is greater than 72 °C (162 °F) while the boost pressure is greater than 70 kPa (10 psi).

• The "Fan with Engine Retarder in High Mode" is programmed to "YES" and the retarder has been on at least two seconds.

• The "A/C Switch Fan On-Time" is programmed to a value above 0 and the A/C high pressure switch is Open.

• The ECM is counting after the A/C high pressure switch has closed.

• The "PTO Activates Cooling Fan" parameter is programmed to "Continuous" and the PTO On/Off switch is on.

• The manual fan override switch is on.

The last four items in the list are programmed by the customer in the "Configuration" screen on the Caterpillar Electronic Technician (Cat ET).

Note: With OCT99 and newer software, the ECM will turn the cooling fan "Off" for 10 seconds during an engine shutdown.

Cooling Fan OFF Conditions

The cooling fan will be turned off by the ECM if engine rpm exceeds 2300 rpm or when all the following circumstances are met:

• The engine coolant temperature for the C-10 or the C-12 engines is less than 92 °C (198 °F).

• The engine coolant temperature for the 3406E, C-15, C-16 and C-18 engines is less than 98 °C (208 °F).

• The fan has been on for at least 30 seconds.

• The intake manifold air temperature is less than 53 °C (127 °F).

• The "Fan with Engine Retarder in High Mode" strategy is not active.

• The "A/C High Pressure Switch Strategy" is not active.

• The "PTO Activates Cooling Fan" strategy is not active.

• The manual fan override switch is off.

Three-Speed Fan

The Three-Speed Fan operates in three modes:

• Brake

• Slip

• Direct

The fan is operating at full speed when the "Direct" mode is used. The "Slip" mode is used most often. The "Fan Control Type" parameter must be programmed to "Three-Speed Fan". Two outputs are required for Three-Speed fan control. Output 4 is used for the brake solenoid. Output 5 is used for the slip solenoid. The function of these outputs is automatically determined by the ECM when the "Fan Control Type" parameter is programmed to "Three-Speed Fan". The fan is turned on in the event of a failure in the output circuit. An example would be an open circuit. The ECM provides the power in order to turn off the fan. If the power is interrupted due to an open circuit, the fan will run continuously. This provides a fail safe operation. The ECM turns Off the output circuit power in order to turn on the fan. Additional switching devices that are in the circuit create an open circuit in order to turn the fan "On". Both of the output drivers are in the ON position while the Brake mode is active. However, the fan is off. In Slip mode, Output 4 is off and Output 5 is on. During Direct mode, both output drivers are off. The fan is on at full speed. The ECM controls the mode for the fan. The mode is based on the following conditions:

• Coolant temperature

• Intake manifold air temperature

• Engine operating conditions

Cooling Fan Trip Points (Three-Speed Fan)

The hysteresis can occur when different modes are selected. The trip points are set at different values. The values depend on increasing temperature and decreasing temperature. The ECM will operate the cooling fan under the conditions that are listed in the following charts and graphics.

Illustration 1	g00783987
Trip Points for a Three-Speed Fan ( C-10 and C-12)

Illustration 2	g00784050
Trip Points for a Three-Speed Fan ( 3406E, C-15, C-16 and C-18)

The following conditions will also cause the Three-Speed Fan to operate in Direct Mode:

• The engine retarder is on and the engine retarder selector switch is in the High position. The "Fan with Engine Retarder in High Mode" parameter must be programmed to "Yes".

• The PTO On/Off Switch is on. The "PTO Activates Cooling Fan" parameter is programmed to "Yes".

• The A/C high pressure switch is active. The "A/C Pressure Switch Fan On-Time" is programmed to a value that is greater than 0 seconds.

Note: There may be an initial delay before the fan is in the Direct mode. Activation of the fan is dependent on the operating conditions.

A/C High Pressure Switch Input Connected to A/C Control Unit.

An OEM supplied air conditioning control may be used. The air conditioning control determines when the cooling fan should operate. This is based on the following input information: A/C high pressure switch, low pressure switch and evaporator thermostat. The fan output for the air conditioning control is designed to interface with the ECM. The fan output may be connected to the input for the A/C high pressure switch. The input for the A/C high pressure switch is Input 11 of the ECM Connector J1/P1:41. The fan is in the ON position when the A/C high pressure switch is in the OPEN position. This type of control has a time delay. Typically, the "A/C Switch Fan On-Time" is programmed to one second since the air conditioning control provides an additional time delay.

The Cooling Fan Control can be Operated Independently of the ECM.

Operation of the cooling fan control can be controlled independently of the ECM. The OEM installed air conditioning high pressure switch may be used for independent cooling fan control. A cab mounted override switch in the solenoid circuit can also operate the cooling fan.

Troubleshooting

Before troubleshooting the cooling fan circuit, determine the type of fan drive system that is used. The fan drive can use the following controls in order to control the fan:

• Normally open with a pneumatic air solenoid

• Normally closed with a pneumatic air solenoid

• Normally open with an electrically controlled solenoid

• Normally closed with an electrically controlled solenoid

The following OEM installed components may affect the operation of the cooling fan in some applications:

• OEM installed, normally open relay

• The A/C high pressure switch is connected to the ECM or the A/C high pressure switch is independent of the ECM.

• Cab mounted manual override switch

• A timer that keeps the fan in the ON position

• Cooling fan air solenoid valve

Illustration 3	g00675576
This schematic represents the ON/OFF fan with a direct solenoid connection to the ECM and the A/C Pressure Switch connected to the ECM input.

Illustration 4	g00675579
This schematic represents the ON/OFF fan with direct solenoid connection to the ECM and the A/C High Pressure Switch not connected to the ECM input.

Illustration 5	g00675587
This schematic represents the ON/OFF fan with direct solenoid connection to the ECM and the A/C Control Unit is connected to the ECM input.

Illustration 6	g00675591
This schematic represents the ON/OFF fan with a normally closed relay and the A/C High Pressure Switch not connected to the ECM input.

Illustration 7	g00675623
This schematic represents the ON/OFF fan with a normally open relay connection and an A/C High Pressure Switch connected to the ECM input.

Illustration 8	g00675640
This schematic represents the ON/OFF fan with a normally open relay connection and an A/C High Pressure Switch connected to the ECM input.

Illustration 9	g00675642
This schematic represents the ON/OFF fan with a normally closed relay connection and an A/C High Pressure Switch connected to the ECM input.

Illustration 10	g00675646
Three-Speed Fan with Direct Solenoid Connection

Test Step 1. Check the Electrical Connectors and the Wiring

Illustration 11	g00675876
Terminal locations for the ECM

1. Thoroughly inspect the ECM Vehicle Harness Connector J1/P1, the A/C High Pressure Switch Connector, the connections to the Cooling Fan Solenoid, and the firewall bulkhead connectors. Refer to Troubleshooting, " Electrical Connectors - Inspect" for details.

2. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the following connections:
   • Cooling Fan

   • A/C High Pressure Switch

3. Check the ECM connector (Allen Head Screw) for the proper torque of 6.0 N·m (55 lb in).

4. Check the harness and the wiring for abrasion and pinch points from the battery to the ECM. Then, check from the key switch to the ECM.

5. Ensure that the ECM is wired to the cooling fan on the vehicle and/or the A/C high pressure switch. Check for wires that are connected to terminal 11 (Output 5) and for wires that are connected to terminal 41. Input 11 is the A/C high pressure switch of vehicle harness connector P1. If a Three-Speed Fan is used, check for a wire that is connected to terminal 13 (Output 4).

   Refer to Illustration 11 for terminal locations for the ECM.

Expected Result:

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

Results:

• OK - Proceed to Test Step 2.

• Not OK -

  Repair: Repair the wiring or replace the wiring, if necessary. Repair the connectors or replace the connectors, if necessary. Ensure that all of the seals are in the proper place. Ensure that all of the connectors are connected properly.Verify that the repair eliminates the problem.

  STOP

• ECM Not Wired To Fan or Switch - If the ECM is not wired to the cooling fan on the vehicle and/or the A/C high pressure switch, then the ECM is not being used for fan control. STOP

Test Step 2. Check the Programming of the "Fan Control Type" Parameter

1. Connect Cat ET to the data link connector.

2. Check the "Fan Control Type" parameter. Ensure that the parameter is programmed to either "On-Off" or to "Three-Speed Fan", if the ECM is used to control the fan. If the parameter is programmed to "None" and the ECM is connected to the fan, then the fan will always be ON.

Expected Result:

The "Fan Control Type" parameter is programmed to match the vehicle wiring. This is determined in the previous step.

Results:

• OK - Proceed to Test Step 3.

• Not OK - Program the "Fan Control Type" to the correct setting and then recheck the system. If conditions are not resolved, then proceed to Test Step 3.

Test Step 3. Check the A/C Pressure Switch

1. Connect Cat ET to the data link connector.

2. Turn the key switch to the ON position.

3. View the following customer specified parameters.
   • "Fan Control Type"

   • "A/C Switch Fan On-Time"

   Ensure that the "A/C Switch Fan On-Time" is programmed to a greater value than "0". If the "A/C Switch Fan On-Time" is programmed to "0", then the "A/C High Pressure Switch Input" (Input 11) is not used.

   Note: If the "Fan Control Type" parameter indicates "None", then the cooling fan driver is not used.

   View the "A/C High Pressure Switch" status on Cat ET.

Expected Result:

The status of the A/C high pressure switch indicates "ON" or "OFF".

Results:

• OK - The status of the A/C high pressure switch is on or off. Proceed to Test Step 4.

• Not OK - The status of the A/C high pressure switch is "Unavailable". The ECM is not programmed to use the A/C high pressure switch. Proceed to Test Step 5.

Test Step 4. Check the Operation of the A/C Pressure Switch

1. Connect Cat ET to the data link connector.

2. Turn the key switch to the ON position.

3. Access the "A/C High Pressure Switch" status screen on Cat ET.

4. Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.

5. Disconnect the "A/C High Pressure Switch" from the vehicle harness at the switch and use the jumper wire to short the two terminals in the harness connector together.

6. Remove the jumper wire and then insert the jumper wire. At the same time, view the "A/C High Pressure Switch" status on the service tool status screen.

Expected Result:

The status screen indicates that the "A/C High Pressure Switch" is turning to the ON position. Then, the "A/C High Pressure Switch" is turning to the OFF position.

Results:

• OK - The A/C high pressure switch harness is OK. Proceed to Test Step 6.

• Not OK - Proceed to Test Step 7.

Test Step 5. Check Active Codes or Logged Codes

1. Connect Cat ET to the data link connector.

2. Turn the key switch to the ON position.

3. Access the "Logged Diagnostic Codes" and the "Active Diagnostic Codes" on Cat ET.

4. Check for the following diagnostic codes.
   • 110-00 High Coolant Temperature Warning

   • 110-11 Very High Coolant Temperature

   • 110-03 Coolant Temp Sensor Open Circuit

   • 110-04 Coolant Temp Sensor Short Circuit

   Record any logged diagnostic codes. Record any active diagnostic codes.

Expected Result:

Result 1 None of the diagnostic codes that are listed are logged or active.

Result 2 Diagnostic code 110-00, or 110-11 is logged or active.

Result 3 Diagnostic code 110-03 or 110-04 is logged or active.

Results:

• Result 1 - Proceed to Test Step 8.

• Result 2 - The cooling fan is on because of a high coolant temperature.

  Repair: Perform the following diagnostic procedure: Testing and Adjusting, "Cooling System - Check"

  STOP

• Result 3 - The cooling fan is on because of a coolant temperature sensor fault.

  Repair: Perform the following diagnostic procedure: Troubleshooting, "Engine Temperature Sensor Open or Short Circuit - Test"

  STOP

Test Step 6. Check the A/C Pressure Switch by use of a Voltmeter

1. Connect Cat ET to the data link connector.

2. Turn the key switch to the OFF position.

3. Ensure that the A/C high pressure switch is disconnected from the vehicle harness at the switch terminals.

4. Connect a multimeter and measure the resistance between the two terminals of the A/C high pressure switch. The switch must be closed in order to check the resistance.

Expected Result:

The resistance measures 10 Ohms or less.

Results:

• OK - The ECM, the A/C high pressure switch, and the wiring are electrically OK.

  Repair: Check the A/C pressure or send the vehicle to the OEM dealer for repairs.

  STOP

• Not OK -

  Repair: Replace the A/C high pressure switch.Verify that the repair eliminates the problem.

  STOP

Test Step 7. Check the ECM

Illustration 12	g00676088
Connector for the Breakout T

1. Connect Cat ET to the data link connector.

2. Turn the key switch to the OFF position.

3. Disconnect the ECM vehicle harness connector J1/P1.

4. Remove terminal 41 (Output 11) from the vehicle harness connector P1.

5. Install a 140-2266 Cable (Seventy-Pin Breakout) between connectors J1 and P1.

6. Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.

7. Connect the jumper wire to terminal 5 (AP Sensor/Switch Common) and to terminal 41 (Input 11) of the breakout T.

   Refer to Illustration 12.

8. Turn the key switch to the ON position.

9. Access the "A/C High Pressure Switch" status screen on Cat ET.

10. Remove the jumper wire and then insert the jumper wire. At the same time, watch the "A/C High Pressure Switch" status on Cat ET.

Expected Result:

The status screen indicates that the "A/C High Pressure Switch" status is off when the jumper wire is in place. The status screen indicates "ON" when the jumper wire is removed.

Results:

• OK - The ECM is OK.

  Repair: If a problem still exists, then the problem is in the OEM wiring. Repair the problem or send the vehicle to the OEM dealer for repair. Verify that the repair eliminates the problem.

  STOP

• Not OK -

  Repair: Temporarily connect a test ECM. Ensure that the "A/C Pressure Switch Fan On-Time" parameter is programmed in the same manner as the suspect ECM. Use Cat ET to check the ECM. If the problem is resolved with the test ECM, install the suspect ECM. If the problem returns with the suspect ECM, replace the ECM.Verify that the repair eliminates the problem.

  STOP

Test Step 8. Check Intake Manifold Air Temperature and the Coolant Temperature

1. Connect Cat ET to the data link connector.

2. Turn the key switch to the ON position.

3. Monitor the status for "Engine Coolant Temperature" and "Intake Manifold Air Temperature" in order to verify that the temperatures are changing as the engine warms up.

Expected Result:

The "Engine Coolant Temperature" and the "Intake Manifold Air Temperature" appear to have the correct reading.

Results:

• OK - Proceed to Test Step 9.

• Not OK -

  Repair: Temporarily connect another sensor. Test the new sensor by checking "Intake Manifold Air Temperature" and "Engine Coolant Temperature" again. If the problem is resolved with the new sensor, then install the old sensor in order to verify that the problem returns. If the problem returns, then replace the old sensor.Verify that the repair eliminates the problem.

  STOP

Test Step 9. Check the Circuit for the Cooling Fan Solenoid

Illustration 13	g00676097
Connector for the breakout T

1. Connect Cat ET to the data link connector.

2. Turn the key switch to the ON position.

3. Access the "On-Off Cooling Fan Special Test" for a fan that cycles "Off" and "On". Access the "Three-Speed Fan Slip Output" or the "Three-Speed Fan Brake Output Special Test" for a Three-Speed Fan. Access each menu in the order that follows: Diagnostics, Diagnostic Tests and Special Test.

   NOTE: If any override switches are installed, the switch must be in the OFF position.

4. Cycle the "Special Test" to the ON position and to the OFF position. Listen for the solenoid to click. You may need to be near the engine in order to hear the click of the solenoid.

Expected Result:

An audible clicking is heard, and the solenoid appears to be operating properly.

Results:

• OK - The cooling fan circuit from the ECM to the solenoid is functioning properly at this time.

  Repair: If a problem still exists, then the problem is in the OEM wiring. Repair the problem or send the vehicle to the OEM dealer for repair.Verify that the repair eliminates the problem.

  STOP

• Not OK - Proceed to Test Step 10.

Test Step 10. Check the ECM

1. Turn the key switch to the OFF position.

2. Disconnect the ECM vehicle harness connector J1/P1.

3. Remove terminal 11 (Output 5) from the vehicle harness connector P1.

4. Connect a breakout T between the J1 and P1 ECM connectors.

5. Connect a voltage test lamp between terminal 11 (Output 5) and terminal 67 (Negative Battery) of the breakout T.

6. Turn the key switch to the ON position.

7. For a fan that cycles on and off, access the "On/Off Cooling Fan Special Test" on Cat ET.

   Cycle the "On/Off Cooling Fan Special Test" to the ON position and to the OFF position. At the same time, watch the voltage test lamp.

8. For a Three-Speed Fan, access the "Three-Speed Fan Slip Output" and the "Three-Speed Fan Bake Output" in the special tests.

   Cycle the "Three-Speed Fan Slip Output" to the ON position and to the OFF position. At the same time, watch the voltage test lamp.

   Connect the voltage test lamp to terminal 13 (Output 4) and terminal 67 (-Battery) of the breakout T.

   Cycle the "Three-Speed Fan Brake Output" to the ON position and to the OFF position. At the same time, watch the voltage test lamp.

   Refer to Illustration 13 for the location of Output 4 and Output 5.

   NOTE: A multimeter can not be used in place of the voltage test lamp when the ECM output is tested.

Expected Result:

The voltage test lamp turns to the ON position when the test is "Active". The voltage test lamp turns to the OFF position when the test is "Not Active".

Results:

• OK - The ECM cooling fan relay is functioning properly.

  Repair: If a problem still exists, then the problem is in the OEM wiring. Repair the problem or send the vehicle to the OEM dealer for repair.Verify that the repair eliminates the problem.

  STOP

• Not OK -

  Repair: Temporarily connect a test ECM. Use the special test to check the ECM cooling fan circuit. If the problem is resolved with the test ECM, install the suspect ECM. If the problem returns with the suspect ECM, replace the ECM.Verify that the repair eliminates the problem.

  STOP