Gxt V055-01 Diagnostic Analyzer Manuel d'utilisateur télécharger pdf (Page 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

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Gxt V055-01 Diagnostic Analyzer Manuel d'utilisateur Page 8