54
Scanner Function
Scanner Operation
Functional Tests
The
Functional Tests
selection is used to access vehicle-specific subsystem and guided
component tests. Available tests vary by manufacturer, year, and model, and only the available
tests display in the menu.
There are four general types of functional test operations:
•
Information Tests
—are read-only tests, like selecting “VIN” from a Functional Tests menu to
display the VIN of the identified vehicle.
•
Toggle Tests
—switch a component, such as a solenoid, relay, or switch, between two
operating states.
•
Variable Control Tests
—command a certain value for a system or component, such as
varying the spark timing in 1° increments or the EGR valve duty cycle in 10% increments.
•
Reset Tests
—reset the adaptive, or learned, values that are stored in the electronic control
module.
Selecting
Functional Tests
opens a menu of test options that varies by make and model.
Selecting a menu option either activates the test or opens a submenu of additional choices. Follow
all screen instructions while performing tests. How and what information is presented on the
screen varies according to the type of test being performed.
IMPORTANT:
Do not enter any functional tests while driving on a road test. During some functional tests, the
ECM makes changes to ignition timing, fuel delivery, and other engine functions, which may affect
engine operation and vehicle control.
Some toggle and variable control tests display functional test controls at the top of the screen with
data stream information below (
).
Figure 4-33
Sample functional test controls
