Can a bad ignition coil cause fuse to blow? 2016 Nissan Altima

Just wanted some insight from more seasoned techs, as I have never run into this situation before.

BACKGROUND:
-So the other day I had a 2016 Nissan Altima, Crank No Start. Customer said it just died in traffic one day when he went to hit the gas.

PROCESS:
-Did all the diag, found no spark, no power to coils, which led me to the fuse. It was busted (fuse 44, 15A for ignition coils).

-I put a new fuse in it and she started right up. Idled well for a long time, but the moment I tapped the gas it died! Fuse was busted again. Oddly enough, after that, power probe showed ground on the power wires for the coils (and at the fuse) with key on, nothing with key off. OK, seems like a short? But all the exposed wiring and harnesses checked out. Wiggling harnesses and connectors changed nothing.

-At this point I was suspect of either IPDM or coils. Replaced fuse, and started up with one coil unplugged, revved to see if fuse popped. Repeated this for each coil. Nothing. Plugged all coils in and revved to try and get fuse to pop again. BUT, it wouldn't even do it anymore! Ran beautifully.

-Idled with all coils on, scoped current ramps on all coils, mirror images all at about 10A peak. Square signal waves from PCM good.

CONCLUSION/QUESTION:
-Ultimately, I advised customer that we replace the ignition coils to eliminate that possibility. However, I've never seen a coil-on-plug cause that, especially without any misfires or other symptoms taking precedence.
1. Is it possible for a coil-on-plug to fail intermittently in this way (internal short), causing the fuse to blow? Anyone ever experienced this?
2. Could it have been a problem with the internal transistor for one of the coils being stuck on or something?
3.How would you even test/confirm a case like that?



Thanks in advance,
Ken

Ken,
Yes, a failing coil can absolutely cause a fuse to open.
It looks (according to Shop Key) like that fuse feeds only the ignition coils.
You could remove the fuse, install a fused loop, and current ramp all 4 coils at the same time with a voltage trace as a sync on #1 coil turn on signal while revving the engine to see which one was not playing nice.
It might not have revealed anything once the problem went away however.
How did the plugs look? Crappy old plugs will over work the coils too.

You could remove the fuse, install a fused loop, and current ramp all 4 coils at the same time with a voltage trace as a sync on #1 coil turn on signal while revving the engine to see which one was not playing nice.

This was going to be my suggestion. Your 10A reading sounds exactly right for this ignition system.

I might keep an eye out for a harness problem that only occurs when the engine torque pulls the harness one way or the other. See if the same problem happens when you shift to Drive, or Reverse.

Maybe even just turn the key on and rock the car back and forth against the parking pawl. If the problem happens with the engine off, the ignition coils had nothing to do with it.

And so the saga concludes.

It ended up doing it again early this morning. On VERY close inspection this time I noticed the wire for one of the two small ground islets on top of the engine had a sneaky little split in it (see picture). Assuming that's coil ground. Replaced fuse, wiggled wire and it sparked, car died. BINGO.... or so I thought.

Repaired wire, replaced fuse, but now fuse started popping immediately with engine off. Turns out there was a second break further up the harness, this time in the power wire to coil 3. Harness was rubbed through by the bolt for front camshaft sensor (see picture). So 2 breaks in the circuit. One intermittent short to ground, one break in the ground. Go figure. Thanks for the advice guys!

Ken

Good find Ken! Thanks for the update