Dual Fan

DTC P0691-P0694 (Duel Fan)

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 P0691
- Fan Control 1 Circuit Low Voltage

DTC P0692
- Fan Control 1 Circuit High Voltage

DTC P0693
- Fan Control 2 Circuit Low Voltage

DTC P0694
- Fan Control 2 Circuit High Voltage




Diagnostic Fault Information






Circuit/System Description

The engine control module (ECM) grounds the low speed relay, which is the Fan Low relay, and the high speed relay, which is the Fan High relay, control circuits through an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line that is monitored by the ECM. When the ECM is commanding a component ON, the voltage potential of the control circuit should be low, near 0 volts. When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high, near battery voltage. If the ECM detects that the actual state of the control circuit does not match the expected state, a DTC will set.


Conditions for Running the DTCs

* DTC P0606 is not set.
* The system voltage is more than 9 volts.
* The engine is running.



Conditions for Setting the DTCs

* An improper voltage level has been detected on the cooling fan relay control circuit.
* The condition must be present for a minimum of 5 seconds.



Action Taken When the DTC Sets

DTCs P0691, P0692, P0693 and P0694 are Type B DTCs.


Conditions for Clearing the DTC

DTCs P0691, P0692, P0693 and P0694 are Type B DTCs.


Reference Information
Schematic Reference

Engine Cooling Schematics (Electrical Diagrams)
Connector End View Reference

* Master Electrical Component List (Component Locations)
* Component Connector End Views (Connector Views)

Description and Operation

Cooling Fan 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)
* Electrical Center Identification Views (Application and ID)

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

Ignition ON, command each relay ON and OFF with a scan tool. Feel or listen to verify that each relay turns ON and OFF with each command.


Circuit/System Testing

1. Ignition OFF, disconnect the affected relay.
2. Ignition ON, connect a test lamp between the positive terminal at the battery and the relay control circuit terminal 86.
3. Command the 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 ON, test the relay control circuit for a short to ground. If the circuit tests normal, replace the ECM.


• If the test lamp is always OFF, test the relay control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

4. Connect a 20A fused jumper wire between the positive voltage terminal at the battery and the fan voltage supply circuit terminal 87 and verify fan activation.

• If the fan does not activate, test the fan voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the fan.

5. Ignition ON, connect a 20A fused jumper wire between the relay switch voltage supply circuit terminal 30 and the fan voltage supply circuit terminal 87 and verify fan activation.

• If the fan does not activate, test the relay switch voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, replace the relay.

6. Ignition ON, verify that a test lamp illuminates between the relay coil voltage supply circuit terminal 85 and ground.

• If the test lamp does not illuminate, test the relay coil voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, replace the relay.

7. If all circuits and the ECM test normal, replace the affected relay.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Engine Coolant Fan Motor Replacement (Service and Repair)
* Control Module References (Programming and Relearning)