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P0481



DTC P0480, P0481, P0691, P0692, P0693, or P0694 (3.6L (LY7 - Gas, 6 Cylinder, 3.6L, SFI, V6))

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 control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.


In low speed operation, the ECM applies ground to the coil side of the cooling fan 1 relay. This energizes the coil and applies voltage directly to the left cooling fan through the switch side of the relay. The left fan is connected in series to the right cooling fan through the normally closed contacts of the series/parallel (S/P) fan relay. The series circuit operates both fans at low speed.


In high speed operation, the ECM applies a ground to the coil side of the cooling fan 1 relay, the fan S/P relay, and the fan 2 relay. When energized, the fan 2 relay applies voltage directly to the right cooling fan through the switch side of the relay. Simultaneously, the fan 1 relay and the fan S/P relay provide ignition voltage and a direct path to ground for the left cooling fan. With both fans connected in a parallel circuit, each fan receives full voltage and operates at high speed.


Conditions for Running the DTC

* The ignition voltage is between 8-18 volts.
* The engine speed is more than 40 RPM.
* The ECM driver transitions from ON to OFF or from OFF to ON.



Conditions for Setting the DTC

P0480

The ECM detects an open on the low speed cooling fan relay control circuit for more than 1 second.

P0481

The ECM detects an open circuit on the high speed cooling fan relay control circuit for more than 1 second.

P0691

The ECM detects a short to ground on the low speed cooling fan relay control circuit for more than 1 second.

P0692

The ECM detects a short to voltage on the low speed cooling fan relay control circuit for more than 1 second.

P0693

The ECM detects a short to ground on the high speed cooling fan relay control circuit for more than 1 second.

P0694

The ECM detects a short to voltage on the high speed cooling fan relay control circuit for more than 1 second.


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.


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 (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. Listen or feel the relay click.
2. 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.

Important: 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:

* Low speed fan 1 relay terminal R68
* High speed fan 2 relay terminal R81
* S/P fan relay terminal R78


• 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.


Important: The following test must be performed on all three fan relay circuits.


3. Test for 2.6-4.6 volts between the ground and the relay coil control circuit terminal listed below:

* Low speed fan 1 relay terminal R69
* High speed fan 2 relay terminal R82
* S/P fan relay terminal R76


• If less than the specified range, test the appropriate relay coil control circuit for an open/high resistance or for a short to ground. 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.


Important: The following test must be performed on all three fan relay circuits.


4. Connect a test lamp between the relay coil control circuit and the relay coil ignition circuit terminals listed below:

* Low speed fan 1 relay terminal R69 and terminal R68
* High speed fan 2 relay terminal R82 and terminal R81
* S/P fan relay terminal R76 and terminal R78

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 applicable relay.
2. Test for 70-110 ohms between terminals 85 and 86 of the relay.

• If the resistance is not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

* 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 ohms between terminals 30 and 87A.

• If greater than the specified value, replace the relay.

5. Install a 20A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87.

• If greater than the specified value, replace the 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


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