ECM checks the ignition coil operation every 10 seconds and if signals indicating open or
short circuit, ECM will set a fault code and engine warning lamp will turn on.
as you see there is specific fault code for each ignition coil so considering
the fault code you have perform the following diagnostic procedure for that ignition coil.
before doing anything it is very important to review the ignition coil wiring diagram.
as soon as you turn the ignition switch to on position, power supply will be provided
on ignition coils via engine main relay, so you must have battery voltage on that pin,
there is also ignition coil fuse to provide this power supply. also ignition coil is controlled by
PCM using the other wire that is called control line. when engine is running according to the
engine firing order, PCM will activate the control line so primary coil will be activated
and there will a magnetic field around the primary coil. as soon as PCM cuts the control line,
magnetic field in primary circuit will collapse and it will induce a high voltage in secondary
coil that must be used in spark plug to ignite the air fuel mixture inside the cylinder.
before removing the ignition coils you can check the waveform of them to see if they
work correctly also you can get some more information through the waveform
to have this waveform you must be using an oscilloscope and you can only get
the waveform from the primary coil circuit and one the control line is shown in here
here you can see an explanation of an ignition coil waveform.
Dwell time is when control line is connected and primary coil is creating magnetic field. Peak
voltage is the increased voltage on primary coil after collapsing the magnetic field
and spark duration is the time that spark is happening. you can see a comparison between
two cases of ignition coil waveforms in left case discharge voltage is too low
so wide spark plug gap and lean air fuel mixture could be the cause and the right case
has got a long spark duration that could be from narrow spark plug gap or rich air fuel mixture
and this is a case study of ignition coil waveform which is affected by a faulty spark plug
first step after checking the waveform is to disconnect the ignition coil connector turn
the ignition switch to on position and to measure the supply voltage which should be battery voltage
if there is not any power on all ignition coils check the ignition coil fuse which
is normally in the engine fuse box otherwise check the wiring
if power supply is correct to perform the next test turn the ignition switch off,
disconnect the battery negative terminal and disconnect the PCM connectors.
when both PCM and ignition coil connectors are disconnected check the continuity
between the power and control line. there should not be any continuity in this case
if you see the continuity you must check the wiring to find the short circuit
this section shows you how to test the continuity between
the ignition coil power supply and control line
now it's time to check the short to ground in the control line. when both connectors
are disconnected check the continuity between the control line and the good ground. there
should not be any continuity in this case otherwise control line is shorted to the ground
for testing the open circuit on control line, test how much resistance there is in
control line by using a multimeter your measurement must be less than one ohm.
if there is not anything wrong with the wiring remove the ignition coil and test
the primary coil internal resistance as shown here
also test the secondary coil internal resistance is shown here