Use this procedure under the following situation:
Use this procedure to determine if the cooling fan (output 5) or the A/C high pressure switch (input 11) is operating correctly.
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" or one of the variable speed options. The Caterpillar factory default is None.
- "A/C Fan On Time" is programmed between one second and 600 seconds.
- A wire is present in the ECM vehicle harness connector J1/P1 (terminal 11) which is output 5 (cooling fan solenoid). This occurs if an On/Off type of fan is used.
- Perform the Special Test for the "On/Off Cooling 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
- Air inlet temperature sensor
- Exhaust brake
- PTO on/off switch
- OEM installed A/C high pressure switch
- Manual fan override switch
A 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. Program the "Fan Control Type" parameter to "ON/OFF". The fan will be off when the ECM output is ON (energized). When the ECM activates the fan, the fan will remain on for a minimum of 30 seconds except for the following conditions:
- Engine start-up
- 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 (700 to 800 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
The ECM will turn the cooling fan ON under any of the following circumstances if engine speed is less than 2750 rpm:
- The engine is not running.
- Engine cranking
- The coolant temperature is greater than 96 °C (205 °F).
- Active diagnostic code for the coolant temperature sensor
- The inlet manifold air temperature is greater than 87 °C (189 °F).
- The inlet manifold air temperature is greater than 72 °C (162 °F) while the boost pressure is greater than 70 kPa (10 psi).
- The manual fan override switch is on.
- The "Fan with Exhaust Brake ON" is programmed to "YES" and the exhaust brake 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 last four items in the previous list are dependent upon the programming of the Customer Parameters.
Note: The ECM will turn OFF the cooling fan for 10 seconds during engine shutdown.
Cooling Fan OFF Conditions
The cooling fan will be turned OFF by the ECM if engine rpm exceeds 2800 rpm or when all the following circumstances are met:
- The coolant temperature is less than 92 °C (198 °F).
- The fan has been ON for at least 30 seconds.
- The inlet manifold air temperature is less than 53 °C (127 °F).
- The strategy for the exhaust brake is not active and the "Fan with Exhaust Brake ON" parameter is programmed to "YES".
- The A/C high pressure switch is not active.
- The PTO on/off switch is in the OFF position and the "PTO Activates Cooling Fan" parameter is programmed to "Continious".
- The manual fan override switch is OFF.
A/C High Pressure Switch Input Connected to A/C Control Unit.
A control unit for the A/C that is supplied by the OEM may be used. The control unit for the A/C determines when the cooling fan should operate. This is based on the following input information:
- A/C high pressure switch
- low pressure switch
- evaporator thermostat
The output for the fan for the control unit to the A/C is designed to interface with the ECM. The output for the fan 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 terminal 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 control unit for the A/C 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 1 | g00766507 |
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. | |
| The following conditions will turn the Fan ON for Illustration 1. | |
| Circuit | Condition that will turn the Fan ON |
| Coolant temperature sensor | The coolant temperature is greater than 96 °C (205 °F). A diagnostic code for the coolant temperature sensor is active. |
| Exhaust brake | The "Fan with Exhaust Brake ON" parameter is programmed to "YES". The exhaust brake is on at least two seconds. |
| OEM installed A/C high pressure switch | The "A/C Switch Fan On-Time" is programmed to a value above 0. The switch circuit is open or on. The external timer is counting or the ECM timer is counting. |
| The engine rpm is less than 2750 rpm. | The engine is cranking. The engine has been running two seconds or the ignition key is ON and the engine OFF. |
| Air inlet temperature sensor | The temperature in the air inlet manifold is greater than 87 °C (189 °F). The temperature in the air inlet manifold is greater than 72 °C (162 °F) while the boost pressure is greater than 70 kPa (10 psi). |
| OEM installed manual fan override switch | There is an open circuit in the switch or the switch is ON. |
| OEM installed cooling fan air solenoid valve | Open solenoid circuit |
| Circuit breaker for the cooling fan | Tripped breaker or open circuit |
| Dedicated PTO on/off switch | The "PTO Configuration" is programmed. The "PTO Activates Cooling Fan" is programmed. There is a short circuit in the switch or the switch is on. |
 | |
| Illustration 2 | g00766679 |
This schematic represents an on/off fan with a direct solenoid connection to the ECM and the A/C high pressure switch is not connected to the ECM input. | |
| The following conditions will turn the Fan ON for Illustration 2. | |
| Circuit | Condition that will turn the Fan ON |
| Coolant temperature sensor | The coolant temperature is greater than 96 °C (205 °F). A diagnostic code for the coolant temperature sensor is active. |
| Exhaust brake | The "Fan with Exhaust Brake ON" parameter is programmed to "YES". The exhaust brake is on at least two seconds. |
| OEM installed A/C high pressure switch | The switch circuit is open or ON. |
| The engine rpm is less than 2750 rpm. | The engine is cranking. The engine has been running for two seconds or the ignition key is in the ON position and the engine off. |
| Air inlet temperature sensor | The temperature in the air inlet manifold is greater than 87 °C (189 °F). The temperature in the air inlet manifold is greater than 72 °C (162 °F) while the boost pressure is greater than 70 kPa (10 psi). |
| OEM installed cooling fan air solenoid valve | Open solenoid circuit |
| Circuit breaker for the cooling fan | Tripped breaker or open circuit |
| Dedicated PTO on/off switch | The "PTO Configuration" is programmed. The "PTO Activates Cooling Fan" is programmed. There is a short circuit in the switch or the switch is ON. |
 | |
| Illustration 3 | g00675587 |
This schematic represents the on/off fan with a direct solenoid connection to the ECM and the control unit for the A/C connected to the ECM input. | |
| The following conditions will turn the Fan ON for Illustration 3. | |
| Circuit | Condition that will turn the Fan ON |
| Coolant temperature sensor | The coolant temperature is greater than 96 °C (205 °F). A diagnostic code for the coolant temperature sensor is active. |
| Exhaust brake | The "Fan with Exhaust Brake ON" parameter is programmed to "YES". The exhaust brake is on at least two seconds. |
| OEM installed A/C control unit | The "A/C Switch Fan On-Time" parameter is programmed to a value above 0 seconds. The A/C control unit circuit is open. The external timer is counting or the ECM timer is counting. |
| The engine rpm is greater than 2750 rpm. | The engine is cranking. The engine has been running two seconds or the ignition key is on the ON position and the engine off. |
| Air inlet temperature sensor | The temperature in the air inlet manifold is greater than 87 °C (189 °F). The temperature in the air inlet manifold is greater than 72 °C (162 °F) while the boost pressure is greater than 70 kPa (10 psi). |
| OEM installed manual fan override switch | There is an open circuit in the switch or the switch is on. |
| OEM installed cooling fan air solenoid valve | Open solenoid circuit |
| Circuit breaker for the cooling fan | Tripped breaker or open circuit |
| Dedicated PTO on/off switch | The "PTO Configuration" is programmed. The "PTO Activates Cooling Fan" is programmed. There is a short circuit in the switch or the switch is on. |
 | |
| Illustration 4 | g00766689 |
This schematic represents the on/off fan with a normally closed relay and the A/C high pressure switch that is not connected to the ECM input. | |
| The following conditions will turn the Fan ON for Illustration 4. | |
| Circuit | Condition that will turn the Fan ON |
| Coolant temperature sensor | The coolant temperature is greater than 96 °C (205 °F). A diagnostic code for the coolant temperature sensor is active. |
| Exhaust brake | The "Fan with Exhaust Brake ON" parameter is programmed to "YES". The exhaust brake is on at least two seconds. |
| OEM installed A/C high pressure switch | The circuit for the switch is closed or the switch is on. |
| The engine rpm is less than 2750 rpm. | The engine is cranking. The engine has been running two seconds or the ignition key is on the ON position and the engine off. |
| Air inlet temperature sensor | The temperature in the air inlet manifold is greater than 87 °C (189 °F). The temperature in the air inlet manifold is greater than 72 °C (162 °F) while the boost pressure is greater than 70 kPa (10 psi). |
| OEM installed cooling fan air solenoid valve | The solenoid is energized. |
| OEM installed cooling fan relay | There is an open circuit on the coil side of the relay. |
| Dedicated PTO on/off switch | The "PTO Configuration" is programmed. The "PTO Activates Cooling Fan" is programmed. There is a short circuit in the switch or the switch is on. |
 | |
| Illustration 5 | g00845731 |
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. | |
| The following conditions will turn the Fan ON for Illustration 5. | |
| Circuit | Condition that will turn the Fan ON |
| Coolant temperature sensor | The coolant temperature is greater than 96 °C (205 °F). A diagnostic code for the coolant temperature sensor is active. |
| Exhaust brake | The "Fan with Exhaust Brake ON" parameter is programmed to "YES". The exhaust brake is on at least two seconds. |
| OEM installed A/C high pressure switch | The "A/C Switch Fan On-Time" parameter is programmed to a value above 0 seconds. The switch circuit is open or the switch is on. The external timer is counting or the ECM timer is counting. |
| The engine rpm is less than 2750 rpm. | The engine is cranking. The engine has been running two seconds or the ignition key is on the ON position and the engine off. |
| Air inlet temperature sensor | The temperature in the air inlet manifold is greater than 87 °C (189 °F). The temperature in the air inlet manifold is greater than 72 °C (162 °F) while the boost pressure is greater than 70 kPa (10 psi). |
| OEM installed cooling fan relay | Open circuit in either coil or contact side of relay |
| OEM installed cooling fan air solenoid valve | Open solenoid circuit |
| Circuit breaker for the cooling fan | Tripped breaker or open circuit |
| Dedicated PTO on/off switch | The "PTO Configuration" is programmed. The "PTO Activates Cooling Fan" is programmed. There is a short circuit in the switch or the switch is on. |
 | |
| Illustration 6 | g00845732 |
This schematic represents the on/off fan with a normally open relay connection and an A/C high pressure switch connected between the solenoid and the relay. | |
| The following conditions will turn the Fan ON for Illustration 6. | |
| Circuit | Condition that will turn the Fan ON |
| Coolant temperature sensor | The coolant temperature is greater than 96 °C (205 °F). A diagnostic code for the coolant temperature sensor is active. |
| Exhaust brake | The "Fan with Exhaust Brake ON" parameter is programmed to "YES". The exhaust brake is on at least two seconds. |
| OEM installed A/C high pressure switch | The switch circuit is open or the switch is ON. |
| The engine rpm is less than 2750 rpm. | The engine is cranking. The engine has been running two seconds or the ignition key is on the ON position and the engine off. |
| Air inlet temperature sensor | The temperature in the air inlet manifold is greater than 87 °C (189 °F). The temperature in the air inlet manifold is greater than 72 °C (162 °F) while the boost pressure is greater than 70 kPa (10 psi). |
| OEM installed cooling fan relay | Open circuit in either coil or contact side of relay |
| OEM installed cooling fan air solenoid valve | Open solenoid circuit |
| Circuit breaker for the cooling fan | Tripped breaker or open circuit |
| Dedicated PTO on/off switch | The "PTO Configuration" is programmed. The "PTO Activates Cooling Fan" is programmed. There is a short circuit in the switch or the switch is on. |
 | |
| Illustration 7 | 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. | |
| The following conditions will turn the Fan ON for Illustration 7. | |
| Circuit | Condition that will turn the Fan ON |
| Coolant temperature sensor | The coolant temperature is greater than 96 °C (205 °F). A diagnostic code for the coolant temperature sensor is active. |
| Exhaust brake | The "Fan with Exhaust Brake ON" parameter is programmed to "YES". The exhaust brake is on at least two seconds. |
| OEM installed A/C high pressure switch | The "A/C Switch Fan On-Time" parameter is programmed to a value above 0 seconds. The switch circuit is open or the switch is on. The external timer is counting or the ECM timer is counting. |
| The engine rpm is less than 2750 rpm. | The engine is cranking. The engine has been running two seconds or the ignition key is on the ON position and the engine off. |
| Air inlet temperature sensor | The temperature in the air inlet manifold is greater than 87 °C (189 °F). The temperature in the air inlet manifold is greater than 72 °C (162 °F) while the boost pressure is greater than 70 kPa (10 psi). |
| OEM installed manual fan override switch | There is a short circuit in the switch or the switch is on. |
| OEM installed cooling fan air solenoid valve | The solenoid is energized. |
| OEM installed Cooling Fan Relay | Open circuit in coil side of relay |
| Dedicated PTO on/off switch | The "PTO Configuration" is programmed. The "PTO Activates Cooling Fan" is programmed. There is a short circuit in the switch or the switch is on. |
Test Step 1. Inspect Electrical Connectors and Wiring.
 | |
| Illustration 8 | g00675876 |
Terminal locations for the ECM | |
- 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.
- 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
- Cooling fan
- Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).
- Check the harness and the wiring for abrasion and pinch points from the battery to the ECM. Then, check from the ignition key switch to the ECM.
- 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.
Refer to Illustration 8 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.
- Connect ET to the cab data link connector.
- Check the "Fan Control Type" parameter. Ensure that the parameter is programmed to"On-Off", 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:
- Yes - Proceed to Test Step 3.
- No - 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. Use ET to Check the A/C Pressure Switch.
- Connect ET at the cab data link connector.
- Turn the ignition key switch to the ON position.
- 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 ET.
- "Fan Control Type"
Expected Result:
The status of the A/C high pressure switch indicates ON or OFF.
Results:
- Yes - The status of the A/C high pressure switch is ON or OFF. Proceed to Test Step 4.
- No - 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. Use ET to Check the Operation of the A/C Pressure Switch.
- Connect ET to the cab data link connector.
- Turn the ignition key switch to the ON position.
- Access the "A/C High Pressure Switch" status screen on ET.
- Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.
- 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.
- 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:
- Yes - The A/C high pressure switch harness is OK. Proceed to Test Step 6.
- No - Proceed to Test Step 7.
Test Step 5. Use ET to Check Active Codes or Logged Codes.
- Connect ET to the cab data link connector.
- Turn the ignition key switch to the ON position.
- Access the "Logged Diagnostic Codes" and the "Active Diagnostic Codes" on ET.
- 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.
- 110-00 High Coolant Temperature Warning
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 either of the following diagnostic procedures: Troubleshooting, "0110-00 High Coolant Temperature Warning" Troubleshooting, "0110-11 Very High Coolant Temperature"
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. Use a Voltmeter to Check the A/C Pressure Switch.
- Connect ET to the cab data link connector.
- Turn the ignition key switch to the OFF position.
- Ensure that the A/C high pressure switch is disconnected from the vehicle harness at the switch terminals.
- 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:
- Yes - 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
- No -
Repair: Replace the A/C high pressure switch.Verify that the repair eliminates the problem.
STOP
Test Step 7. Use ET to Check the ECM.
 | |
| Illustration 9 | g00676088 |
Connector for the Breakout T | |
- Connect ET to the cab data link connector.
- Turn the ignition key switch to the OFF position.
- Disconnect the ECM vehicle harness connector J1/P1.
- Remove terminal 41 (output 11) from the vehicle harness connector P1.
- Install a breakout T between connectors J1 and P1.
- Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.
- Connect the jumper wire to terminal 5 (ap sensor/switch common) and to terminal 41 (input 11) of the breakout T.
Refer to illustration 9.
- Turn the ignition key switch to the ON position.
- Access the "A/C High Pressure Switch" status screen on ET.
- Remove the jumper wire and then insert the jumper wire. At the same time, watch the "A/C High Pressure Switch" status on 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:
- Yes - 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
- No -
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 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. Use ET to Check Inlet Manifold Air Temperature and the Coolant Temperature.
- Connect ET to the cab data link connector.
- Turn the ignition key switch to the ON position.
- Access the status screen. Locate the "Coolant Temperature" and the "Inlet Manifold Air Temperature" status screen. Monitor the status screen for a few minutes in order to verify that the temperatures are changing as the engine warms up.
Expected Result:
The "Coolant Temperature" and the "Inlet Manifold Air Temperature" appear to have the correct reading.
Results:
- Yes - Proceed to Test Step 9.
- No -
Repair: Temporarily connect another sensor. Test the new sensor by checking "Inlet Manifold Air Temperature" and "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. Use the "Cooling Fan Solenoid Special Test" on ET to Check the Circuit.
 | |
| Illustration 10 | g00676097 |
Connector for the Breakout T | |
- Connect ET to the cab data link connector.
- Turn the ignition key switch to the ON position.
- Access the "Cooling Fan Special Test". Access each menu in the order that follows:
- Diagnostics
- Diagnostic Tests
- Special Test
NOTE: If any override switches are installed, the switch must be in the OFF position.
- Diagnostics
- 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:
- Yes - 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
- No - Proceed to Test Step10.
Test Step 10. Use the "Cooling Fan Solenoid Special Test" on ET to Check the ECM.
- Turn the ignition key switch to the OFF position.
- Disconnect the ECM vehicle harness connector J1/P1.
- Remove terminal 11 (Output 5) from the vehicle harness connector P1.
- Connect a breakout T to the ECM connector J1 and vehicle harness connector P1.
- Connect a voltage test lamp between terminal 11 (Output 5) and terminal 67 (negative battery) of the breakout T.
- Turn the ignition key switch to the ON position.
- Access the "Cooling Fan Special Test" on ET.
Cycle the "Cooling Fan Special Test" to the ON position and to the OFF position. At the same time, watch the voltage test lamp.
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 when the test is "NOT Active".
Results:
- Yes - The output for 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
- No -
Repair: Temporarily connect a test ECM. Use the special test on ET 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