GxT V055-01 Diagnostic Analyzer - Manual (Page 8)

8
This test measures the input power and response of
the coil. If there are no readings, or they are obviously
wrong, check your connections.
COMPOSITE SCREEN
RPM is read by the black Primary Amps probe from the
current pulses drawn by the ignition coils. Battery voltage
comes from the red and black Battery Clips. The next
display line shows the average ignition primary amps
and the average milliSeconds it took for all coils to build
up the current during dwell.
DRIVE MILLISECONDS
The Drive MilliSeconds reading is the total dwell time
from the time the coil begins to charge to the time of
plug firing. In current-limiting electronic ignitions, the
difference between drive and build time is the “hold”
period.
MULTISPARK
Some ignition systems spark more than once during
each power stroke. If so, the words “Multispark Ign.” will
appear with the number of sparks per ignition.
INDIVIDUAL COIL READINGS
Press the up and down arrows to see individual coil readings. The numerical screen shows Peak Amps,
Build and Drive milliSeconds per coil. Two more screens show peak amps and build milliSeconds in bar
graph format.
PEAK AMPS
Look for equal current in each ignition coil, between 4 and 11 amps. If the primary ignition supply circuit
has bad connections, all amps may be low.
BUILD MILLISECONDS
These readings are useful for checking current-regulating ignitions that take a fixed time to build coil
current. Typical build time is 3 to 4 mSec. This time is nearly constant up to about 3000 RPM, and then
begins to shorten as RPM increases. If battery voltage is low, build times will lengthen.
Build time is a function of battery voltage, the inductance of the coil primary, and the peak amps level at which
the ignition module is set to regulate. The following relationships exist, if other factors are constant.
Long build time may be caused by high resistance in the primary circuit. Remember that the coil primary
circuit includes the power feed, the coil primary, the drive module, and its connection to ground. Increased
resistance from loose or corroded connections limits the primary current. This may cause lower peak amps
or longer build time readings.
Short build time may be caused by shorted coil windings.
Build time will be slightly longer while cranking, because of reduced battery voltage. If the ignition module
is not regulating at all, then Peak Amps can be High and Build can be Long. Both will be limited only by
the primary circuit resistance and battery voltage.
Ignition Primary - DIS