MODEL IDENTIFICATION
Note. This article applies to 2001 and 2000 late body style vehicles. For 2000 early body style vehicles, see ELECTRONIC "C" & "K" SERIES - OLD STYLE article.
| Series (1) | Model |
|---|---|
| "C" | 2WD Pickup, Sierra, Silverado, Suburban, Tahoe & Yukon |
| "K" | 4WD Pickup, Sierra, Silverado, Suburban, Tahoe & Yukon |
| (1) Vehicle series is fifth character of VIN. | |
| (1) | Vehicle series is fifth character of VIN. |
MODEL IDENTIFICATION - TRUCKS
DESCRIPTION & OPERATION
Note. For repair procedures not covered in this article, see appropriate POWER RECIRCULATING BALL article.
Note. Some models are also equipped with Real Time Damping (RTD) suspension.
The Electronic Variable Orifice (EVO) power steering system is controlled by one of two control modules depending on suspension options. The Electronic Variable Orifice (EVO) power steering system consists of the following
- Power steering pump, discharge and return hoses, steering box and linkage.
- Power steering fluid flow actuator (EVO solenoid) valve, mounted on power steering pump discharge port.
- Steering Wheel Position (SWP) sensor mounted in lower bearing of steering column.
- Suspension Control Module (SCM) located behind right rear quarter trim panel (with RTD).
- Body Control Module (BCM) located under lower left side of instrument panel, below steering column (without RTD).
- Powertrain Control Module (PCM) located in engine compartment, on left inner wheelwell.
- Vehicle Control Module (VCM) located in engine compartment, on left inner wheelwell.
- Vehicle Speed Sensor (VSS) mounted on transmission or transfer case (4WD) output shaft.
The system increases or decreases amount of fluid leaving power steering pump. When vehicle is at a standstill or moving at low speeds, EVO system allows full hydraulic fluid flow for maximum assist. As vehicle speed increases, variable actuator orifice closes at pump, reducing fluid flow to stiffen steering wheel response for improved road feel and directional stability.
Note. Steering wheel position sensor is also referred to as "handwheel speed sensor" or "steering wheel rotation sensor".
Steering Wheel Position (SWP) sensor detects rapid movement when defensive driving maneuvers are made. The control module uses SWP sensor input to adjust current to fluid flow actuator. If control module detects a fault, EVO system will become disabled, allowing maximum power assist. When ignition is turned off and vehicle is restarted, control module resets and allows EVO system operation until it detects another fault. The control module has self-diagnostics and stores diagnostic trouble codes. See DIAGNOSIS & TESTING . Codes will clear after 100 ignition cycles without a malfunction.