Ignition Coil Replacement: GM 3100

This video from Standard highlights helpful tips to consider when replacing an Ignition Coil on a GM 3100 application.
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Video Transcript:
Let's take a look at replacing the ignition coil on this GM 3,100 engine. Now you can see it's got two coil towers here. And so there's three different coil packs on this particular engine and they've all got companion cylinders. So cylinders one and four are a companion pair, three and six and two and five. And so the entire circuit on both cylinders has to be intact before replacing the coil or even before condemning it.
But let's talk about replacing the coil, so you can see they're located up here on top rear of the engine, not too bad to access here. So on this particular vehicle, we're going to go ahead and replace the number two and five coil. And now the one next to it is for cylinder six and three. And the one next to that is cylinders one and four. So we have one, four, six, three, two, five, and on the OE coil towers here, it's actually got the numbers printed.
So I'm going to have to pop off the plug wires here, but in order to prevent any confusion, when I put it back together, I'm going to take a marker and just write the cylinder numbers on the plug wire. So when I go back to install it, I don't have to worry about mixing them up. So we'll pop the two plug wires off, and I'm going to take my quarter inch ratchet with a 5.5 millimeter socket, and there's just two bolts holding it down here. So you can see if we look at the coil there's one on the top and one on the bottom. And so we'll just unbolt those and lift the coil off.
So in order to access the lower one, sometimes you just get to feel a little bit by hand that it's the only bolt right there. There's no special tricks, no universal sockets, no twisting anything like that. It's pretty straight forward. Once you can feel it, put the socket on and we'll back it out. Yeah. So once we got both of the bolts out, now we're ready to remove the coil. So we can gently pick it up and slide it off. Now on the ignition module, there's two electrical tabs in there that the coil sits on. So we want to be careful when we remove it, because slide it directly up off there, make sure they're good and clean.
Now, of course, the new coil comes with a little rubber insulator boot that goes on the ignition module itself. So we'll just take a 90-degree pick and I'm going to slide those up off there. And as you can see, we're going to slide this into place. So now we've got the insulator in place. I can take the coil, slide it back down over the little electrical tab there.
I'll take my two bolts here. Get them started by hand, get them both snug down good. Once both of the bolts are tight, I can now take my spark plug wires. They're previously marked. And you'll see if they're in the loom. It's pretty hard to reach the incorrect coil tower anyways, but we'll install them back on there in a way we go. Now, typically, if you've got a faulty coil, it's not a bad idea to replace the secondary condition, meaning the spark plug wires and the spark plugs themselves, just to make sure we don't want to damage our new coil or the ignition module for that matter.
So it's always a good idea to at least test these components. And if they haven't been replaced within the last 50,000 miles or 30,000 miles, it's a good idea to go ahead and replace them as well. Hopefully now you understand what it takes to replace one of the ignition coils on a GM 3,100 engine.