When servicing the variable effort steering electronic variable orifice (EVO) system, perform the following steps in order. Not following these steps may result in the loss of important diagnostic data. This may lead to difficult and time-consuming diagnostic procedures.

1. Perform a vehicle preliminary diagnostic inspection. This should include:

•	Inspection of the power steering fluid reservoir for proper steering fluid level, signs of contamination and for proper steering fluid type. Refer to Fluid and Lubricant Intermittents and Poor Connections Diagnosis Recommendations in Maintenance and Lubrication.

•	Inspect the EVO/Passlock™ module and system for any wiring damage.

•	Inspect the steering assist control solenoid, connector and wiring.

•	Inspect for poor power steering pump performance. Refer to Diagnosis of Power Steering System in Power Steering System.

•	Inspect the power steering gear for leaks, malfunction or poor performance. Refer to Diagnosis of Power Steering System in Power Steering System.

•	Inspect the vehicle speed sensor and wiring.

•	Inspect the power steering fluid hoses for binding and sharp bends.

2. Perform a power steering system test. Refer to Power Steering System Test in Power Steering System.
3. Perform the variable effort steering system check. Refer to Variable Effort Steering System Check . If any DTCs are displayed, note the last malfunction that occurred. Diagnose and repair this malfunction first.
4. If no DTCs or mechanical component malfunctions are present, or if the condition is intermittent and not reproducible, test drive the vehicle while using the automatic snapshot feature of the scan tool. Perform normal acceleration, stopping, and turning maneuvers. If this does not reproduce the malfunction, refer to Intermittents and Poor Connections Diagnosis .
5. After all the system malfunctions have been corrected, clear the EVO DTCs and test drive the vehicle.