Bonneville America Forums Forums Off Topic Discussion Forums Lounge Ignition coil on my truck keeps blowing any ideas?

last fall I had no spark in my 02 GMC Sierra. So I was reading how to diagnose the problem and ended up replacing the ignition coil and ignition module before giving up and having "the man" replace the ignition rotor.

so a couple months back I got stuck again with no spark and had to have it towed to the same guy and he replaced the ignition coil. Which I thought was strange since I just replaced it before when I had it in there to replace the rotor.

oh well, I figured I messed something up when testing it with the multimeter, I told myself.

Then last week the truck wouldnt start again and I was nowhere near the usual guy's shop and had to get towed into another place. He told me it was the ignition module at first then called back and said it ended up being the ignition coil AGAIN.

So thats three coils in less than a year, what gives?

Is there a fuseable link that runs to that? Maybe the fuseable link is shot? There should be a ground wire that runs from one of the coil screws to the fire wall also.

How about the plug gap? Too big a gap would really strain the coil.

Right, if its not well grounded you can have problems. Also I am not sure on an 02 but there use to be a pickup coil under the rotor. Those things could cause all kinds of trouble.

thanks guys, Bucky that links pretty helpful. And I definately gotta check that gap.

Another thing I just thought of this morning is the mechanic tested my battery and told me it was low on cranking amps and I should replace the battery. I told him no of course cause I can handle that.

But do you think the battery not having enough cranking amps can make the coil work harder during ignition? Its actually the original battery from 2002 that came with the truck..haha.

I would have to look under your hood to verify for your year, but the trucks a little bit older would start having ignition problems when the rubber weather strip that attaches to the cowel and prevents water from the hood dripping down on the ignition wears it then allows that and causes ignition failure.

yeah Ian, the mechanic that replaced my ignition rotor assembly said that they go bad for that reason. I never got around checking the weather stripping because I figured (at the time) that it was just an old rotor and needed replacing. I'll have to look into that.

Have your mechanic check the pickup coil at the distributor......Angelis

A lot of coils are designed so that the secondary winding is terminated at the battery connection. If the primary wires are connected backward, you get some 40 - 80 K-volts across the winding instead of the few hundred it was designed for. So, if the problem persists, try switching the low voltage wires.
Which brings us to another possibility. If the plug gaps are too wide or you have resistor type plugs and/or wiring and the wiring is old and tired, it can cause the voltage across the secondary winding to go so high as to break down the insulation.