C0502

CIRCUIT DESCRIPTION
The Electronic Variable Orifice (EVO) Module supplies a 0 - 850 milliamperes pulse width modulation current (percent Duty Cycle) to the EVO Solenoid. This current is used to extend or retract the actuator valve inside the solenoid. This in turn will regulate an orifice on the power steering pump causing the fluid flow output to modulate. This results in an increase or decrease in steering wheel efforts. With 0 milliampere supplied to the EVO Solenoid, the valve will be fully retracted, providing maximum fluid flow and power steering assist. With 850 milliamperes supplied to the EVO Solenoid, the valve will extend decreasing fluid flow and minimize power steering assist. The EVO Module is constantly adjusting current flow to the EVO Solenoid based on vehicle speed and steering wheel position, thus providing vehicle speed related power steering assist.

CONDITIONS FOR SETTING THE DTC
1. When there is an open or short to ground in circuits 1294 or 1295 when the ignition switch has been cycled to the OFF and then to the ON position.
2. When voltage is below 0 volts.
- The above conditions must be met for 1 second or longer.

ACTION TAKEN WHEN THE DTC SETS
The EVO Module will not send any current to the EVO Solenoid. This will cause the EVO Solenoid valve to retract, providing maximum fluid flow and full power steering assist at all times.

CONDITIONS FOR CLEARING THE DTC
1. A history DTC will clear after 100 consecutive ignition cycles has occurred without a fault.
2. History and current DTCs can be cleared by using the Tech 2 scan tool.

DIAGNOSTIC AIDS
- An "Intermittent" problem may be caused by a poor connection, break in the wire insulation exposing the internal wire, or a wire that is broken inside the insulation.
- The EVO Module and the Vehicle Control Module (VCM) should be thoroughly checked for terminals that have backed out, broken locks, improperly formed or damaged terminals, weak terminal retaining tension, or for proper routing.
- The EVO Solenoid valve may be stuck providing uncalculated power steering assist.

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TEST DESCRIPTION
The step numbers below refer to the same step numbers in the EVO Solenoid Open or Shorted to Ground Diagnostic Table.
1. This step ensures that the "Diagnostic System Check" is performed!
2. This step test will determine if the Electronic Variable Orifice (EVO) Solenoid is open.
3. This step will determine if the Electronic Variable Orifice (EVO) Solenoid is shorted to ground.
4. This step checks for a short to ground or an open to ground in circuits 1294 or 1295.