MODEL IDENTIFICATION
Note. This article applies to 2000 early body style vehicles only. For 2000 late body style vehicles, see ELECTRONIC - "C" & "K" SERIES - NEW STYLE article.
| Series (1) | Model |
|---|---|
| "C" | 2WD Pickup, Tahoe & Yukon |
| "K" | AWD Escalade, & 4WD Pickup, 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.
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 solenoid actuator mounted on power steering pump discharge port.
- EVO/Passlock(R) module mounted to instrument panel carrier, underneath the radio.
- Steering Wheel Position (SWP) sensor mounted in lower bearing of steering column.
- Vehicle Speed Sensor (VSS) mounted on transmission or transfer case (4WD) output shaft.
- Powertrain Control Module (PCM) located in engine compartment, on left inner wheel well panel.
- Vehicle Control Module (VCM) located in engine compartment, on left inner wheel well panel.
The EVO system increases or decreases the amount of fluid leaving the power steering pump. When vehicle is at a standstill or moving at low speeds, the system allows full hydraulic fluid flow for maximum power assist. As vehicle speed increases, a variable orifice closes at pump, reducing fluid flow providing a stiffer steering wheel response to improve road feel and directional stability at highway speeds.
Note. Steering wheel position sensor is also referred to as "handwheel speed sensor" or "steering wheel rotation sensor".
Steering Wheel Position (SWP) sensor detects abrupt or evasive movement when defensive steering maneuvers are made and signals the EVO/Passlock(R) module to increase fluid flow reducing steering effort. The EVO/Passlock(R) module uses this sensor input to adjust the current to fluid flow solenoid actuator. If the EVO/Passlock(R) module detects a fault, the EVO system is disabled, allowing maximum power assist. When ignition is turned off and vehicle is restarted, the EVO/Passlock(R) module resets and allows EVO operation until it detects another fault. EVO/Passlock(R) module has self-diagnostics and stores diagnostic trouble codes. See DIAGNOSIS & TESTING . Codes will clear after 100 ignition cycles without detecting a fault.
Note. When replacing EVO/Passlock(R) module, reprogramming of learned data must be performed.