P0691
DTC P0480, P0691, or P0692 (2.0)
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 Speed Output Circuit
DTC P0691
- Cooling Fan Speed Output Circuit Low Voltage
DTC P0692
- Cooling Fan Speed Output Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated (PWM) signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the engine cooling fan motor in relation to the pulse width modulated signal. The cooling fan speed can be adjusted from 10 percent to 90 percent duty cycle. 90-94 percent is considered high speed fan.
The ECM monitors the voltage on the cooling fan speed control circuit driver output. Voltage is near B+ when the driver is OFF, and near ground when the driver is ON. If the difference between the actual and expected voltage exceeds a calibrated value, a DTC will set.
Conditions for Running the DTC
* The engine speed is more than 80 RPM.
* The system voltage is between 10-18 volts.
Conditions for Setting the DTC
P0480
The ECM detects 0 voltage on the output during commanded transitions.
P0691
The ECM detects low voltage on the output while commanded OFF.
P0692
The ECM detects high voltage on the output while commanded ON.
Action Taken When the DTC Sets
DTC P0480, P0691, and P0692 are Type B DTCs.
Conditions for Clearing the DTC
DTC P0480, P0691, and P0692 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 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
1. Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
2. Ignition ON, command the cooling fan speed from 10-90 percent with a scan tool. The fan speed should transition with the commanded states.
Circuit/System Testing
Important: The Circuit/System Verification must be performed first or misdiagnosis may result.
1. Ignition OFF, disconnect the cooling fan speed control module.
2. Ignition OFF, install a test lamp between the cooling fan speed control circuit terminal 4 and B+. The lamp should be OFF.
• If the lamp is ON, test the cooling fan speed control circuit for a short to ground. If the circuit tests normal, replace the ECM.
3. Ignition ON, command the cooling fan speed from 10-90 percent with a scan tool. The brightness of the lamp should change with the commanded states.
• If the lamp brightness does not change correctly, test the cooling fan speed control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
4. If the ECM and the control circuit test normal, replace the cooling fan assembly.
Repair Instructions
* Cooling Fan and Shroud Replacement (LE5, L61) (Service and Repair)Cooling Fan and Shroud Replacement (LNF) (Service and Repair)
* Control Module References (Programming and Relearning)for replacement, setup, and programming
Repair Verification
1. Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
2. Ignition ON, command the cooling fan speed from 10-90 percent with a scan tool. The fan speed should transition with the commanded states.