Cooling Fan Inoperative
Cooling Fan Inoperative
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructionsprovides an overview of each diagnostic category.
Circuit/System Description
The hybrid engine cooling fan system consists of two electrical cooling fans, two resistors, three engine control module (ECM) fan output control drivers, and five fan relays. The relays are arranged in a series/parallel configuration that allows the ECM to operate the fans at low, medium, or high speed depending on engine cooling requirements. The ECM controls the five relays by grounding the relay control circuits.
Diagnostic Aids
* The ECM has the capability of providing command to the fan relays even when a scan tool output control is being used. Always refer to the fan control command parameters on the scan tool to know which fans are being commanded ON by the ECM.
* The scan tool cooling fan output control operates as follows:
- Fan Relay 1 operates both fans at a low speed
- Fan Relay 2 operates both fans at medium speed
- Fan Relays 1, 2, and 3 operates both fans at high speed
Reference Information
Schematic Reference
Engine Cooling Schematics [1][2]Cooling System
Connector End View Reference
Component Connector End Views Connector End Views By Name
Description and Operation
Cooling Fan Description and Operation Cooling Fan
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Programming and Relearningfor scan tool information
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0480 or P0481 is not set.
• If a DTC is set, refer to DTC P0480, P0481, or P0482 P0480.
2. Ignition ON, command the cooling fans ON and OFF at high, medium, and low speed with a scan tool. Verify that both fans turn ON and OFF when changing between the commanded states.
Circuit/System Testing
Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description .
2. Ignition ON, verify the scan tool hood position parameter displays Open.
• If the hood position does not display Open, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.
3. Ignition OFF, disconnect the cooling fan relays.
4. Ignition ON, verify that a test lamp illuminates between the Fan Control relay ground circuit terminal 87 and B+.
• If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
5. Connect a 30 A fused jumper between the Fan Control relay switch circuit terminal 30 and the relay ground circuit terminal 87. This will complete the left side fan ground circuit. Leave this jumper in place for the remainder of this procedure.
Note: The following test must be performed on the high, low, and both medium speed relay circuits.
6. Ignition ON, verify that a test lamp illuminates between ground and the relay switched ignition circuit terminal listed below:
* Fan Low Relay terminal 87
* Fan Mid 1 Relay terminal 87
* Fan Mid 2 Relay terminal 30
* Fan High Relay terminal 30
• If the test lamp does not illuminate, test the appropriate relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay switch B+ circuit fuse is open, test the relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the appropriate G10 cooling fan.
7. Connect a 30 A fused jumper between the cooling fan relay circuit terminals listed below:
* Fan High Relay terminals 87 and 30
* Fan Low Relay terminals 87 and 30
Verify the appropriate fan is activated.
• If the corresponding cooling fan does not activate, test the relay controlled output circuit and the cooling fan ground circuit for an open/high resistance. If the circuits tests normal, test or replace the appropriate G10 cooling fan.
8. Connect a 30 A fused jumper between the cooling fan relay circuit terminals listed below:
* Fan Mid 1 Relay terminal 87 and 30
* Fan Mid 2 Relay terminal 30 and 87
The appropriate fan should activate and operate at a reduced speed.
• If the corresponding cooling fan does not activate, test the relay controlled output circuit for an open/high resistance. If the circuit tests normal, test or replace the appropriate R10 cooling fan resistor.
• If the corresponding cooling fan activates, replace the appropriate cooling fan relay.
9. Ignition OFF, install the Fan Control relay.
10. Ignition ON, connect a 30 A fused jumper wire between the Fan Low relay terminals 87 and 30. Both cooling fans should activate and operate at a low speed.
• If both fans do not activate, test the Fan Control Relay switched output circuit terminal 87A for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the Fan Control relay.
11. If all the circuits test normal, test or replace the appropriate cooling fan relay.
Component Testing
1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 50-90 ohm between terminals 85 and 86.
• If not within the specified range, replace the cooling fan relay.
3. Measure the resistance between the terminals listed below:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
The DMM should display OL.
• If less than the specified range, replace the cooling fan relay.
4. Test the Fan Control Relay for less than 2 ohm between terminals 30 and 87A.
• If greater than the specified range, replace the cooling fan relay.
5. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohm between terminals 30 and 87.
• If greater than the specified range, replace the cooling fan relay.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Relay Replacement
* Underhood Electrical Center or Junction Block Replacement Underhood Electrical Center or Junction Block Replacement
* Engine Coolant Fan Motor Replacement
* Engine Coolant Fan Resistor Replacement