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Refer to Test Number 9--Ohms Test (sections 1-7) for Ohmmeter use.
The purpose of the ballast resistor (when equipped) is to limit the
current available to the ignition coil when the vehicle is running.
Failure of this resistor results in a dead engine.
If the engine trys to
start when cranking, but the instant you release the key,it stops, then
you may have an "open" ballast resistor.
You can feel and hear the engine
cranking speed increase because the ignition system is trying to take over.
With the ignition key off, locate the ballast resistor and remove the
wires that are connected to it.
(The ballast resistor is usually a
white ceramic block with brass terminals and is generally located on the
fire wall.
If you have difficulty locating it, consult your vehicle service
manual.)
NOTE:
Many Chrysler Corporation Electronic Ignition systems use a dual
ballast resistor,
One side of this resistor functions exactly as indicated
above.
The other side is the auxiliary ballast resistor and it should read
approximately 5 ohms.(Figure 45)
PROCEDURE
The OHMS scale is used to test the ballast resistor.
To test the ballast
resistor, disconnect all leads at their terminals to pr@vent possible damage
to the analyzer or to prevent inadverdent measurement of other circuits
connected to it.
CONNECTIONS:
Ii
2.
Insert the white plug OHMS lead into the corresponding tester socket,
Connect the RED and BLACK clips to the ballast resistor as shown.
Some
ballast resistors are dual units--such as on some Chrysler automobiles,
while others are single units--or resistor wires.
Some ignition
systems utilize the ballast resistor in the coil primary (see ignition coil
test).
TEST PROCEDURE:
i.
The Ohmmeter will read full scale at the extreme right hand side,
INFINITY
( Oo
), with the BLACK and RED clips disconnected.
When the clips are connected together, the meter pointer will
read zero on the left (short circuit or zero ohms).
2.
To measure the ballast resistor, connect the RED and BLACK clips as
shown in Fi_ure 45 .
Set the Function Selector Switch to the OHMS
position.
3.
Set the Range Selector Switch to the LOW scale.
Typical readings should
be between 0.5 and 7.5 ohms.
IMPORTANT: Consult your vehicle service manual for the exact OHMS value
for your car.
The value read should be very close to the specified value
as large differences can cause damaged points or electronic ignition module
(when too low).
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