2005 blazer ignition coil failed on me and I could see white burn marks on the sides of it. I replaced it with a new one and now I see white marks starting to appear again. Does anyone know what would case this to happen ? Is it a grounding issue ? What can I do to correct this ? Any help or advise is appreciated. Thanks in advance.

 

The first thing that comes to mind is the resistance of the coil to distr lead or the spark plug wires. If not then the distr/rotor/timing.

Any codes?

How is it running?

What is the condition of the ignition wires? Measure their resistance, especially the coil lead.

How old are the spark plugs and what shape are they in?


George

 

Here is an article on how to diagnose a GM 4.3L Ignition control module and a IGNITION COIL. The Ign. control module has 4 wires and the ignition coil has three wires and are mounted side by side on the passenger side of the engine compartment.

. https://easyautodiagnostics.com/gm/4...test-the-icm-1

 

There is nothing wrong with testing your coil and ICM and Jim’s article is a good one. If that’s where you want to start then by all means carry on.

The reason that I started with the condition of your wires is because your symptom is one of an overheated and/or cracked coil that can develop rated spark energy but cannot discharge it properly. This is the same reason why you should not pull spark plugs wires without giving them a proper air gap to jump. Wires with excessive resistance are approaching an open condition where the coil is trying to jump a huge air gap and can then overheat/crack and start discharging externally. I am assuming that you did not have two bad coils in a row. I should have provided you with my reasoning initially.


George

 

They wires are new and it did it with the old spark plug wires as well. Thanks for all your help. I'll have to keep working on this problem. I did notice today that I only have 2 wires going to to coil. I find that strange. I'll have to look at some diagrams. The plug has 2 outer wires and no middle wire. It looks like it's this way from factory because its blocked off on the factory clip.Also the guy that wired my car starter in tied a wire into to tach wire on the coil wire (white/black stripe) wire.

 

OK then my initial guess may be wrong. I would still test the wire resistance anyhow, especially the coil lead. On your truck nothing ties into the signal wire from the ICM to the coil so any add on may be disturbing the signal to the coil. Why was that wire added? The coil has two wires and the high voltage output. Pink is fused power and wht/blk is the ground side switching from the ICM. At the ICM pink is once again fused power, Wht/Blk is the ground side switch control to the coil, white is the timing control from the PCM and blk/wht is frame ground. Good luck





George

 

I found my problem. It was the signal wire to the coil. When my car starter was installed 10 years ago the person at the shop I took it to did a horrible spice and butchered that wire. Hopefully my overheated coil , cam sensor and crank sensor are ok. I can see that the coil was over heating by the white marks on the sides I would like to thank everyone for their help here.Very much appreciated guys 😉