Car won't start

[pikelk98]

Yesterday my stabiltrack and ABS light came on while driving and then today they were gone. I drove less than 2 miles to a store and when I went to start the car back up it was dead. I just replaced the battery back in December, and AAA confirmed that the battery was fine when they came so I know it's not that. Got it back home and realized the battery 40 amp fuse was blown. I spoke with my mechanic and he said he had another GMC in the shop with the same issue and it ended up being a flywheel issue that was blowing the fuse, Any one else had anything similar happen?

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[Fless]

I'd be curious about what flywheel issue would cause a blown fuse. Any more info on this?

 

[pikelk98]

I'd be curious about what flywheel issue would cause a blown fuse. Any more info on this?

My mechanic said he's wracked his brain for years trying to figure that out himself. Apparently his customer took the car to his dealership and that's what the service department told him was the problem.

 

[OR VietVet]

Not buying the flywheel problem unless someone can explain to me the details. You said you got it back home and "then" discovered the battery 40 amp fuse was blown. How did you get it home? I have seen where the 40 amp fuse was blown because of not hooking battery jump cables correctly....etc. One time, when that fuse blew, the customer said the lights flashed for a second and the horn honked for a second.

 

[pikelk98]

Not buying the flywheel problem unless someone can explain to me the details. You said you got it back home and "then" discovered the battery 40 amp fuse was blown. How did you get it home? I have seen where the 40 amp fuse was blown because of not hooking battery jump cables correctly....etc. One time, when that fuse blew, the customer said the lights flashed for a second and the horn honked for a second.

I had it towed back home and the following morning checked all of my fuses to see if that was the problem. That's when I found out the 40 amp was blown. I didn't try to jump my battery as it was new and AAA confirmed that it was fully charged. My mechanic has further confirmed that the 40 amp fuse was blown after I had the truck towed to his shop.

 

[strutaeng]

I "think" technically it's a "flex plate" for automatic (flywheel for manual)...but that doesn't really matter.

I can't see how a fuse (which fuse?) would blow from a flex plate issue. The starter cable goes directly to the battery and it's not fused, so it should technically draw the battery's rated amperage or the cable's amperage. In a typical cranking operation, that's usually only a second on crank/fire up. It's probably just a coincidence on the blown fuse. Those large 40A fuses are for like ABS, AC blower, and I can't remember what else? There's not a starter fuse (only starter relay).

You or your mechanic need to go through the conventional methods to determine why truck doesn't fire:

1. Fuel
2. Spark
3. Air
4. Compression

Note: loss of compression on a cylinder or multiple cylinders WILL cause an uneven crank sound and a corresponding amperage draw difference (that's what a relative compression test essentially looks for: which cylinder(s) is drawing less amps than the rest)

Unless there's a short somewhere related to the blown fuse? Always a possibility...

 

[OR VietVet]

Could have fluid in a cylinder and hydraulic that cylinder and the interaction between the flex plate and starter are effected. He said it would not crank. The list of "4" does not come in to play till the engine is cranking.

 

[strutaeng]

Could have fluid in a cylinder and hydraulic that cylinder and the interaction between the flex plate and starter are effected. He said it would not crank. The list of "4" does not come in to play till the engine is cranking.

Ah, yeah. I definitely missed the "no crank" symptoms. Definitely different approach than a "crank-no-fire" condition.

So easiest thing is to check the starter relay. I've those fail and truck simply won't crank.

Next, go down there with a test light and have a helper crank to see if you have power at the solenoid. Then go from there.

The "bang/tap the starter" while a helper cranks is also an easy and effective test to see if starter is intermittently failing.

I hope this helps OP.

 

[pikelk98]

Ah, yeah. I definitely missed the "no crank" symptoms. Definitely different approach than a "crank-no-fire" condition.

So easiest thing is to check the starter relay. I've those fail and truck simply won't crank.

Next, go down there with a test light and have a helper crank to see if you have power at the solenoid. Then go from there.

The "bang/tap the starter" while a helper cranks is also an easy and effective test to see if starter is intermittently failing.

I hope this helps OP.

Thanks all! My mechanic didn't feel comfortable replacing the fuse being it's so expensive just for it to blow again to be able to discover the problem. I've since transferred the car to another mechanic that specializes in electrical issues to see what caused the fuse to blow in the first place. Fingers crossed it's not going to be an expensive fix.

 

[Doubeleive]

My mechanic said he's wracked his brain for years trying to figure that out himself. Apparently his customer took the car to his dealership and that's what the service department told him was the problem.

the only way feasable I could see that happening is if the starter is freezing up due to broken teeth and causing a high amperage situation that would blow the fusible link on top of the battery but on the k2's the starter is on no fusible link at all to the starter. so it's something else. that 40amp link needs to be ohm tested
i think your mechanic misheard something
so the question is which 40 amp fuse exactly?