[Johnnyboyy]

Hello All,

I have an 2004 TSX MT with 200k miles, a few days ago I was driving and noticed that my battery light had came on and so I went to Autozone and they checked the battery and the guy told me it was at 71% and could be a faulty alternator not getting charge so it is draining the battery but he said it is okay as long as it has over that 70% to drive for a few days, mind you the car battery is relatively new as I have bought it in October 2022. As I came back to drive it close to another 20mins all of the sudden my whole dash light went on and started to flicker then turn off and I started to lose power so i pulled over and got towed to the nearest autozone since it was close night all the shops were closed. One of the workers tried to check my battery but they couldn't even jump it with their car battery jumper, so they took my battery in to get it recharged. So I waited approximately 1-2hrs and I came back in and still it was at 27% so since I had recently purchased this battery they went ahead and warranty me a new battery. The new battery was put in yet there is still no power, so the guy checked my fuse box and said probably the main fuse fried so since everything was already closed I had it towed again to my house and the next day my older brother tested that it was the main fuse has fried and so he ordered a new one and today as he had put in the new fuse 100/70, it had blown right away. He also checked with a pair of wires and it sparked crazy meaning that something is giving way too much charge to the main fuse. Any adivce or informations of what it could be?? Where to start?

Thank you 🙏

 

[merlinj79]

That's gotta be one of the main positive power cables basically shorting to ground somewhere. Could be a cable connector, or could even be inside the alternator or starter. The good news is that there's only so many places where that could happen so it should be easy to find.

Inspect these carefully:

Three grounding straps: make sure they're connected on both ends and not broken, a loose ground strap might possibly bounce around and contact a major positive terminal. Kind of doubt it but they're easy to check.
Battery cables
Alternator Cables
Starter cables
Inspect every big connector you can get to, look for loose connectors, frayed insulation, or something like a loose bracket where it shouldn't be.


Next I would disconnect either the alternator or starter, whichever is easier (be careful where the loose connectors end up). Then try to key on. If the fuse blows again, disconnect the other device.

If it still blows with both disconnected then iit's got to be either a cable somewhere or maybe something in the main fuse block... I'd try taking the fuse block apart, could be a loose fastener got it there and shorted something. Or maybe it's just defective.

But my guess would be starter or alternator... both have moving parts and a direct feed to main positive and ground.

 

[Johnnyboyy]

That's gotta be one of the main positive power cables basically shorting to ground somewhere. Could be a cable connector, or could even be inside the alternator or starter. The good news is that there's only so many places where that could happen so it should be easy to find.

Inspect these carefully:

Three grounding straps: make sure they're connected on both ends and not broken, a loose ground strap might possibly bounce around and contact a major positive terminal. Kind of doubt it but they're easy to check.
Battery cables
Alternator Cables
Starter cables
Inspect every big connector you can get to, look for loose connectors, frayed insulation, or something like a loose bracket where it shouldn't be.


Next I would disconnect either the alternator or starter, whichever is easier (be careful where the loose connectors end up). Then try to key on. If the fuse blows again, disconnect the other device.

If it still blows with both disconnected then iit's got to be either a cable somewhere or maybe something in the main fuse block... I'd try taking the fuse block apart, could be a loose fastener got it there and shorted something. Or maybe it's just defective.

But my guess would be starter or alternator... both have moving parts and a direct feed to main positive and ground.

Yeah, my brother disconnected the cables to the alternator and it blew right away when he put in the in main fuse 100A/70A. He also put in the main fuse from a TL and it turned on but giving a lot of current so had to take it out before it would blow the main fuse 120A/70A. Do you think its best to replace both bad alternator and starter then try again? before everything went out my car was making a whinning/humming noise with the battery light on.

Thank you 🙏

 

[merlinj79]

If the fuse popped with the alternator disconnected then I'd think the alt is not the problem. The alt might be also bad though, if it was pushing a lot of excess current through a short.

But find the short first, then you can figure out if the alt works.

At this point I'd disconnect the starter and see if the car electronics powers up. Easy to do, but you'll need to jack it up.

 

[Johnnyboyy]

If the fuse popped with the alternator disconnected then I'd think the alt is not the problem. The alt might be also bad though, if it was pushing a lot of excess current through a short.

But find the short first, then you can figure out if the alt works.

At this point I'd disconnect the starter and see if the car electronics powers up. Easy to do, but you'll need to jack it up.

Thank you for the helpful tips, it ended up being the alternator being dead and bad that kept frying the main fuse.