Pontiac Fiero 1988 Service Manual page 689

6E3-C4-4 DRIVEABILITY AND EMISSIONS - FUEL INJECTION (PORT)
"C
IGN.
BLK.
CONN.
GRY.
CONN.
PICK-UP
COSL
TACH.
IGNITION COIL
CONNECTOR
DISTRIBUTOR
5-26-87
mm
DISTRIBUTOR CONNECTOR
E C M
423
WHT
430 PPI/WHT
424 TAN/BLK
453 ILK/RED
B4
B5
D5
B3
EST
— REFERENCE
— BY-PASS
5-8-87
'5S1923-6E
CHART C-4B
IGNITION SYSTEM CHECK
(REMOTE COIL/SEALED M O D U L E CONNECTOR DISTRIBUTOR)
2.8L "f"
SERIES (PORT)
3.
Test Description:
Numbers below refer to circled
numbers on the diagnostic chart.
1. Two wires are checked, to ensure that an open is
not present in a spark plug wire.
1A. If spark occurs with 4 terminal distributor
connector disconnected, pick-up coil output is too
low for EST operation.
2. A spark indicates the problem must be the
distributor cap or rotor.
Normally, there should be battery voltage at the
"C" and " + " terminals. Low voltage would
indicate an open or a high resistance circuit from
the distributor to the coil or ignition switch. If "C"
term, voltage was low, but " + " term, voltage is 10
volts or more, circuit from "C" term, to ignition
coil or ignition coil primary winding is open.
Checks for a shorted module or grounded circuit
from the ignition coil to the module. The
distributor module should be turned "OFF," so
normal voltage should be about 12 volts.
If the module is turned "ON," the voltage would be
low, but above 1 volt. This could cause the ignition
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 "Bat." to the tach terminal.
4.
5. Applying a voltage (1.5 to 8 volts) to module
terminal "P" should turn the module "ON" and the
tach. term, 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 generating
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 multi-meters 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 it's terminals which can be
used to trigger the module. The voltage in the
ohm's position can be checked by using a second
meter or by checking the manufacture's
specification of the tool being used.
6. 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 problems
would have been found before this point in the
procedure. A module tester (J24642) could
determine which is at fault.