P0480
DTC P0480, P0481, P0691, P0692, P0693, or P0694
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0480
- Cooling Fan Relay 1 Control Circuit
DTC P0481
- Cooling Fan Relay 2 Control Circuit
DTC P0691
- Cooling Fan Relay 1 Control Circuit Low Voltage
DTC P0692
- Cooling Fan Relay 1 Control Circuit High Voltage
DTC P0693
- Cooling Fan Relay 2 Control Circuit Low Voltage
DTC P0694
- Cooling Fan Relay 2 Control Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The engine cooling fan system consists of one electrical cooling fan, a serviceable resistor module mounted in the cooling fan shroud, and three fan relays. The relays are arranged in a series parallel (S/P) configuration that allows the engine control module (ECM) to operate the fan at low, medium, or high speeds, depending on cooling requirements. The resistor module is a self-contained unit providing a specific resistance through three individual circuits. To activate the fan, the ECM applies ground to the coil side of the applicable fan relays. The cooling fan and fan relays receive battery voltage from the underhood fuse block. The ground path for the operation of the cooling fan is provided at G104.
Conditions for Running the DTC
* The ignition voltage is between 8-18 volts.
* The engine speed is greater than 80 RPM.
* The DTCs run continuously once the conditions above have been met.
Conditions for Setting the DTC
P0480
The ECM detects an open in the cooling fan relay 1 control circuit for greater than 4 seconds, or a cumulative of 30 seconds.
P0481
The ECM detects an open in the cooling fan relay 2 control circuit for greater than 4 seconds, or a cumulative of 30 seconds.
P0691
The ECM detects a short to ground in the cooling fan relay 1 control circuit for greater than 4 seconds, or a cumulative of 30 seconds.
P0692
The ECM detects a short to voltage in the cooling fan relay 1 control circuit for greater than 4 seconds, or a cumulative of 30 seconds.
P0693
The ECM detects a short to ground in the cooling fan relay 2 control circuit for greater than 4 seconds, or a cumulative of 30 seconds.
P0694
The ECM detects a short to voltage in the cooling fan relay 2 control circuit for greater than 4 seconds, or a cumulative of 30 seconds.
Action Taken When the DTC Sets
DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.
Diagnostic Aids
When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.
Reference Information
Schematic Reference
Engine Cooling Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Cooling System Description and Operation (LSA) (Description and Operation)Cooling System Description and Operation (LP1,LY7,LLT) (Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, command the appropriate fan relay ON and OFF with a scan tool. You should hear an audible click.
2. Ignition ON, command the appropriate cooling fan relay, or relays, ON and OFF with a scan tool. Observe the appropriate scan tool FC Relay Circuit Test Status parameters. The parameters should display OK or Not Run in each commanded state.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF, disconnect all three cooling fan relays.
Note: The following test must be performed on all three fan relay circuits.
2. Ignition ON, verify that a test lamp illuminates between ground and the relay coil ignition circuit terminal listed below:
* Fan 1 relay and fan 2 relay terminal 85
* S/P fan relay terminal 86
• If the test lamp does not illuminate, test the relay coil ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay coil ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
Note: The following test must be performed on all three fan relay circuits.
3. Test for 2.6-4.6 V between the ground and the relay coil control circuit terminal listed below:
* Fan 1 relay and fan 2 relay terminal 86
* S/P fan relay terminal 85
• If less than the specified range, test the appropriate relay coil control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
• If greater than the specified range, test the relay coil control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
Note: The following test must be performed on all three fan relay circuits.
4. Connect a test lamp between B+ and the relay coil control circuit terminals listed below:
* Fan 1 relay and fan 2 relay terminal 86
* S/P fan relay terminal 85
5. Command the fan relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
• If the test lamp is always OFF, replace the ECM.
6. If all circuits test normal, test or replace the relay.
Component Testing
1. Ignition OFF, disconnect the appropriate cooling fan relay.
2. Test for 200-240 ohm between terminals 85 and 86 of the relay.
• If not within the specified range, replace the relay.
3. Measure the resistance between the terminals listed below. The DMM should display O.L.
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
• If not the specified value, replace the relay.
4. Test for less than 2 ohm between terminals 30 and 87A.
• If greater than the specified range, replace the relay.
5. Install a 20 A fused jumper wire between B+ and relay terminal 85. Install 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 (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming