C0473

CIRCUIT DESCRIPTION
The Electronic Variable Orifice (EVO)/Passlock module receives the vehicle speed information through the Vehicle Control Module (VCM) of the gasoline engines, or the Powertrain Control Module (PCM) of the diesel engines, and the class 2 data line. With the vehicle speed information, the EVO/Passlock module compares the vehicle speed signal received from the Vehicle Speed Sensor (VSS) with the vehicle speed data received from the class 2 data line. The VSS is a permanent magnet sensor producing an AC signal with varying frequency. The VSS is mounted in the transmission, or the transfer case in selectable four wheel drive models, and is driven off the output shaft. The VSS produces a pulsing AC voltage and the number of pulses increase with the vehicle speed. The VCM/PCM supplies the vehicle speed signal to the instrument cluster and to the EVO/Passlock module.

CONDITIONS FOR SETTING THE DTC
The steering wheel rotation sensor voltage is greater than 4.9 volts for one second or longer.

ACTION TAKEN WHEN THE DTC SETS
The Electronic Variable Orifice (EVO)/Passlock module does not send any current to the PS solenoid actuator. This causes the retraction of the EVO valve. This provides the maximum fluid flow and full power steering assist at all times.

CONDITIONS FOR CLEARING THE DTC
- A history Diagnostic Trouble Code (DTC) will clear after 100 consecutive ignition cycles have occurred without a fault.
- The history and the current DTC can be cleared by using the scan tool.

DIAGNOSTIC AIDS
The scan tool will read the steering wheel position in volts. With the ignition switch in the ON position, and as the steering handwheel speed sensor is rotated, the voltage reading should be 0.2-4.9 volts. The voltage should increase at a steady rate up to 4.9 volts when the wheel is turned, one quarter revolution (90 degrees) in either direction.
- Above 0.2 volts.
- Below 4.9 volts when the steering wheel is rotated one quarter revolution (90 degrees).
Using the scan tool, scan the handwheel speed sensor.
- Above 0.2 volts.
- Turn the steering wheel.
- The scan tool display should increase from above 0.2 volts and below 4.9 volts as the steering wheel is turned one quarter revolution (90 degrees).

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Part 2 Of 2:

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
2. This step prompts the technician to complete some basic checks and to store the Snapshot data. This creates an electronic copy of the data taken when the fault occurred. Refer to this stored information as necessary. When the voltage is 0.2-4.9 volts, the Electronic Variable Orifice (EVO)/Passlock (TM) module uses this voltage to detect changes in the position of the steering wheel and the rate of steering. The system voltage increase and decreases proportionately to the steering wheel rotational speed. If the voltage is not within the specifications, a DTC sets.
5. This step probes the ground circuit and checks the circuit for high resistance, which sets DTC C0473.
6. This step verifies a shorted 5.0 volt reference circuit, which may also set additional DTCs.