Electronic Spark Timing is ENABLED under certain driving conditions.
EVO (On /Off)
On Saturns with power-assisted steering, power steering pressure can
be modulated with the electronic variable orifice (EVO). This valve
changes pressure based on vehicle speed. At slower speeds, the orifice
is commanded ON increasing the power steering pressure, at higher
speeds steering correction is small, therefore less pressure is needed,
the orifice should be commanded OFF.
EVO Output (Duty Cycle%) Range: 0 to 100%
This represents the on-time percentage that the ECM has calculated for
Electronic Variable Orifice (EVO valve) given current vehicle speed. The
solenoid is cycled open and closed to modulate desired power steering
pressure. This percentage should correlate to the actual EVO pressure
(i.e. 30% duty cycle means the EVO should be 30% closed).
EVO Feedback (Duty Cycle %)
This parameter feeds the actual open percentage of the EVO back to the
ECM to verify correct solenoid operation. The ECM will make sure that the
actual solenoid command duty cycle matches the feedback duty cycle.
The solenoid is isolated for more accurate fault detection. Range 0 to
100%.
Fan 1 or 2 (Yes / No)
An indication that the electric cooling fan is on and whether it is operating
at low or high speed (for single fan engines). Some engines have two
fans. The second fan provides extra cooling under extreme conditions.
First Gear (Engaged / Disengaged)
If the ECM is commanding first gear, the screen should show ENGAGED.
Otherwise, the screen should show DISENGAGED.
Fourth Gear (Engaged / Disengaged)
If the ECM is commanding fourth gear, the screen will show ENGAGED.
Otherwise, the screen will show DISENGAGED.
Fuel Cut Off (On / Off)
An indication that the ECM has cut off fuel delivery during deceleration.
Fuel Cutoff PN (On / Off)
If the ECM has detected a clear flood condition in fuel injected vehicles,
this parameter should indicate ON. Otherwise, there is no reason to cutoff
Page 68
GM OPERATIONAL DATA ITEMS
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