Vehicle make/model = 1998 chevy cammaro
Mileage = 128,000
Engine size = 3.8
dash lights = check engine
codes = 1351
work done prior = head gasket replacement
work done to repair = replaced the coils and the electical box they sit
on plus plugs and wires
tip/donation yes
tech = jk
question = I just replaced the head gasket on my car. When I was
finished the car would not start. After playing with it for a bit I figured
out it had no spark. So I replaced the little box the coils sit on (it
was expensive so I took it off a 98 ponitac gran prix gt 3.8) and it
started but the check engine light keeps comming on with a code 1351
saying ignition voltige high and open current. So I got another electrical
box and coils off a 97 comarro 3.8 with the same part# the pontiac was a
different  part# box. It runs alot better with no misses but the same
code keeps comming up. I have replaced the plugs and wires when I did
the head gasket. Now there are 2 things I have noticed 1. The cat is bad
in it and will be replaced in the morning. 2. I found a ground wire to
the electrical box broke so I soldered it back together. Well hope you
can help







JK:
Hello and welcome.
Thanks you very much for the tip/donation.
The Ignition Control Module (ICM) sends signals that the PCM requires for fuel control and
spark advance calculations. At the start of engine crank, the ICM controls spark advance
(Bypass mode.) When the second 3X reference pulse is recognized by the PCM, the PCM
applies 5 volts to the Bypass circuit, commanding the ICM to switch spark advance to PCM
control (IC mode). If the PCM detects an open in the IC circuit, DTC P1351 will set. The
engine will start and may run in Bypass mode timing.
It is possible that damage has occured to the IC control circuit wire, or the low reference
circuit wire between the PCM and the ignition control module. Just be sure the ignition
modules are the same part #
You are going to need a digital multimeter to do some tests.
Fisrt disconnect the pcm(connector C1-blue) and ignition control module. Check for
continuity of circuit 423 (white) between pcm and ignition control module with key off. Then
do the same for circuit 453(red/blk). Less than .5 ohms is ok. If high resistance, or open
circuit on either, you will need to trace the wire from pcm to module very carefiully. Also
look very carefully at terminals inside ignition module connector for damage. Damage may
occured during the several times the connector has been on and off. Also pull lightly on
each individual wire at ignition module connector to make sure the wires do not stretch.
Once again, thank you for the tip/donation.
See schematics i will send in a few moments......

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