DESCRIPTION & OPERATION
The PCM monitors certain parameters (such as engine coolant temperature, vehicle speed, A/C on/off status, A/C pressure, etc) to determine engine cooling fan needs.
The PCM controls the fan speed and operation using a duty cycle output on the Fan Control - Variable (FCV) circuit. The fan controller receives the FCV command and operates the cooling fan at the speed requested (by varying the power applied to the fan motor). See FCV DUTY CYCLE OUTPUT FROM PCM table.
| FCV Duty Cycle Command | Cooling Fan Response/Speed |
|---|---|
| 0-Less Than 5 Percent | Fan Off, Controller Inactive |
| 5-Less Than 10 Percent | Fan Off, Controller Is In Active/Ready State |
| 10-90 Percent | Linear Speed Increase From 20-100 Percent |
| More Than 90-Less Than 95 Percent | 100 Percent |
| 95-100 Percent | Fan Off |
FCV DUTY CYCLE OUTPUT FROM PCM
COMPONENT LOCATIONS
The fan controller is located at or integral to the engine cooling fan assembly.
TROUBLE SHOOTING
Note. To trouble shoot mechanical cooling system components, see GENERAL COOLING SYSTEM SERVICE article in GENERAL INFORMATION.
PRELIMINARY INSPECTION
Verify customer complaint by operating suspected system. Visually inspect for obvious signs of mechanical and electrical damage. Inspect for blown fuses and damaged relays. See WIRING DIAGRAMS . Inspect for loose or corroded connections, damaged wiring harness and/or switches. Check for a broken or partially broken wire inside insulation, which could cause system malfunction but prove good in a continuity/voltage check with system disconnected. Ensure any aftermarket electronic equipment is properly installed. If fault is found, repair as necessary. If no fault is found, see DIAGNOSTIC SYSTEM .
DIAGNOSTIC SYSTEM
For cooling fan electrical diagnostics on 2003 models, see SYMPTOMS in TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE. For cooling fan electrical diagnostics on 2004 models, see SYMPTOMS in TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE.
Removal & Installation
Drain coolant from the degas bottle only. Remove the degas bottle supply hose. Remove the overflow hose. Remove the bolt and the degas bottle. Disconnect the fan motor connector. Remove the two bolts and the fan blade, fan motor and the fan shroud assembly. To install, reverse the removal procedure. Tighten bolts to specification. See TORQUE SPECIFICATIONS .
TORQUE SPECIFICATIONS
| Application | INCH Lbs. (N.m) |
|---|---|
| Degas Bottle Bolts | 89 (10) |
| Fan Shroud Screws | 89 (10) |
TORQUE SPECIFICATIONS
2003
For wiring diagrams, see COOLING FAN in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
2004
For wiring diagrams, see COOLING FAN in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
For wiring diagrams, see COOLING FAN in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
For wiring diagrams, see COOLING FAN in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
For wiring diagrams, see COOLING FAN in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
For wiring diagrams, see COOLING FAN in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
For wiring diagrams, see COOLING FAN in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
For wiring diagrams, see COOLING FAN in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.