Single Fan
DTC P0691-P0694 (Single 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 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 DTC
* The engine is running.
* The system voltage is more than 9 volts.
* DTC P0606 is not set.
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 30 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 appropriate relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
• If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the ignition circuit terminal 30 and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the appropriate relay.
4. Verify that a test lamp illuminates between the ignition circuit terminal 86 and ground.
• If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.
5. Disconnect the harness connector at the cooling fan.
6. Test for less than 1 ohm between the cooling fan ground circuit terminal 1 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the cooling fan.
8. Connect a 20A fused jumper wire between the ignition circuit terminal 86 and the control circuit terminal 87. Verify the cooling fan is activated.
• If the cooling fan does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the cooling fan.
9. Connect a test lamp between the ignition circuit terminal 30 and the control circuit terminal 85.
10. Clear the DTCs with a scan tool.
11. Command the appropriate 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 control circuit for a short to ground. If the circuit tests normal, replace the ECM.
• If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
12. If all circuits test normal, test or replace the appropriate relay.
Component Testing
Relay Test
1. Ignition OFF, disconnect the appropriate relay.
2. Test for 75-90 ohms between terminals 85 and 86.
• 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 1 ohm between terminals 30 and 87A.
• If greater than the specified range, replace the relay.
5. Install a 5A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 1 ohm between terminals 30 and 87.
• If greater than the specified range, replace the relay.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Engine Coolant Fan Motor Replacement (Service and Repair)
* Auxiliary Engine Coolant Fan and Fan Motor Replacement (Service and Repair)
* Control Module References (Programming and Relearning)