90-823225--1 10965E-76 - ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY)
Ignition System Check
(1 of 2)
TO 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. Two spark plug wires are checked, to ensure that
an open is not present in a spark plug wire.
If spark occurs with Ignition Control (IC) connec-
tor disconnected, magnetic field output is too low
for Ignition Control (IC) operation.
2. A spark indicates the problem must be the distrib-
utor cap or rotor.
3. Normally, there should be battery voltage at the
“C” and “+” terminals. Low voltage would indicate
an open or a high resistance circuit from the dis-
tributor to the coil or ignition switch. If “C” terminal
voltage was low, but “+” terminal voltage is 10
volts or more, circuit from “C” terminal to ignition
coil or ignition coil primary winding is open.
4. Checks for a shorted module or grounded circuit
from the ignition coil to the module. The distribu-
tor module should be turned OFF, so normal volt-
age should be about 12 volts.
If the module is turned ON, the voltage would be
low, but above 1 volt. This could cause the igni-
tion coil to fail from excessive heat.
With an open ignition coil primary winding, a
small amount of voltage will leak through the
module from the Battery Positive (B+) to the
“Tach” terminal.
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