90-823225--1 10965E-78 - ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY)
Ignition System Check
(2 of 2)
TO IN-LINE HARNESS (TACH)
TO DISTRIBUTOR
DIST. REFERENCE “HIGH”
BYPASS
DIST. REFERENCE “LOW”
IGNITION CONTROL
TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the
diagnostic chart.
1. Applying a voltage (1.5 to 8 volts) to module ter-
minal “P” should turn the module ON and the
“Tach” terminal voltage should drop to about 7-9
volts. This test will determine whether the module
or coil is faulty or if the pick-up coil is not generat-
ing the proper signal to turn the module “ON.”
This test can be performed by using a DC battery
with a rating of 1.5 to 8 volts. The use of the test
light is mainly to allow the “P” terminal to be
probed more easily. Some digital multimeter can
also be used to trigger the module by selecting
ohms, usually the diode position. In this position,
the meter may have a voltage across its terminals
which can be used to trigger the module. The volt-
age in the ohms position can be checked by using
a second meter or by checking the manufactur-
er’s specification of the tool being used.
2. This should turn OFF the module and cause a
spark. If no spark occurs, the fault is most likely
in the ignition coil because most module prob-
lems would have been found before this point in
the procedure.
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