Coil Packs not getting voltage?

STUART BERMAN

MEMBER
2004 HYUNDAI SONATA
2.4L
4 CYL
2WD
AUTOMATIC
193,666 MILES

54 years I'm turning wrenches and can't figure out why my coil packs aren't getting any voltage when I try to start it, started when my camshaft sensor pigtail came apart, found new ones on eBay wired it up with the correct readings, 12v at the primary wire, 5v at the signal to the ECU and ground, every fuse inside and under the hood are ok, I'm totally lost on what else I need to check, replaced the ignition failure sensor, both coil packs, just no current at the coil packs connector plug!
Only thing left is the crank sensor but I'm not getting any trouble codes for it?

8 Replies

JACOBANDNICKOLAS

MECHANIC
109,867 POSTS

Hi,

Are you getting power to the ignition failure sensor? Power from the ignition fuse in the under-hood junction box to the failure sensor. From there it is sent to each coil via a tan wire with a black tracer. For the circuit to be completed and fire the coil, the PCM needs to provide a ground path via coil 1 white wire and coil 2 orange wire.

So, if you do have power to the coils but they won't fire, either we have an issue with the PCM or the crankshaft position sensor. Keep in mind, the CKP may or may not set a code if it fails. If you have a live data scan tool, check to see if there is an RPM signal when cranking the engine. If you don't have one, see if the tachometer moves at all when cranking.

Let me know what you find.

Take care and Merry Christmas,

Joe

See pics below.

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Saturday, December 24th, 2022 AT 5:57 PM

STUART BERMAN

MEMBER
5 POSTS

There is no power to either coil pack, when I had someone try to start it there no pulse current at the 3 wire pigtail, all fuses are good and there is power to the failure sensor, I have power at the fuel pump, even removed the a/c panel on the dash to check the ECU relay which I can feel clicking on and off, shouldn't there be a live 12v at the coil pack connector with the key on or is it just when starting the test light lights up, I've never ran into this problem before, Hope you have a nice Christmas and if you can think of anything else I'll check back!

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Saturday, December 24th, 2022 AT 7:52 PM

JACOBANDNICKOLAS

MECHANIC
109,867 POSTS

Hi,

Power to the coils should be present with the key on (engine off or on) and in the start position.

Go to the ignition failure sensor. Disconnect the connector and check pin 4 for power and pin 1 for continuity. If you have both, replace the sensor. I believe you replaced it already, but you may have gotten a bad one. If you have power and ground to the sensor, you should see power at the coils unless there is an open circuit between the sensor and coils.

Let me know what you find.

Joe

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Saturday, December 24th, 2022 AT 10:07 PM

STUART BERMAN

MEMBER
5 POSTS

Not sure if you got my last reply, I have 12v to the failure sensor pin 4, pin 1 is in the image I sent, all fuses that lead to the ignition are all working, cranked the engine, no tach reading but still no power at the coils, I'll keep checking back with you to see if can figure something else out, meanwhile I'll keep trying to see on my end, thanks!

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Monday, December 26th, 2022 AT 9:09 AM

JACOBANDNICKOLAS

MECHANIC
109,867 POSTS

Hi,

Looking at your second pic, if you got 12v and used the ground in the connector, you confirmed both are good.

So, connect the sensor and back probe pin 3 (tan/black wire) out of the sensor connector for power. If there isn't any power out, the sensor is bad. If there is and nothing at the coils, then you have an open between the sensor and coils.

Let me know what you find.

Joe