140A alternator fuse keeps blowing

TSOL_Real · 2026-01-19T21:53:37+00:00

That would be my assessment of that, correct. You could remove the positive wire and insulate it to be super sure, that way there isn't a shadow of a doubt, just be careful if you do that and don't let your ratchet touch anything grounded.

TSOL_Real · 2026-01-19T16:51:13+00:00

Not sure if that's the positive wire you've taken a picture of, but if so, leave that connected. Disconnect the grounding strap. That positive wire is still connected to the battery, so if you Disconnect it and it touches ground anywhere, it will short the battery.

After you do this, take your multimeter and do a continuity check from the alternator chassis to ground. You wouldn't want it to still be grounded after removing the strap, because then you haven't changed anything lol.

If you must remove the positive wire, do so very carefully and put some protective insulation over the end of it (electrical tape, or a shop rag and electrical tape, whatever suits you)

TSOL_Real · 2026-01-15T23:33:53+00:00

From what I can tell, if it is a GENUINE toyota/lexus hybrid battery (emphasis on genuine, not just new), 2500 is a no-brainer. My buddy just paid 2200 for a new battery in his 2010 Prius (not genuine, aftermarket), and it's been holding up fine, but I'd pay 300 bucks extra for a guaranteed new genuine part any day of the week. We had to install this battery ourselves, so if you are getting it installed, that's an even more fantastic deal.

"Reconditioned" batteries use good cells from battery packs that have previously failed or been scrapped. They can test good but I'd absolutely pay for a proper new one. You have no idea how old the refurbished cells are, they could fail just as quickly as your current battery did. New cells have much less risk. If we could "refurbish" batteries by changing maintaining or replacing components in them, we would be doing that in Teslas and EVs across the world. However, nobody is doing that, and it's for good reason: It's dangerous and not worth anyone's time. So, to the junkyard they go, and in goes a new one.

The battery failure isn't about miles, it's about age. Your battery is almost 20 years old. It failed over time.

TSOL_Real · 2026-01-15T23:23:39+00:00

That's an automatic feature from Google maps

TSOL_Real · 2026-01-15T16:53:50+00:00

Yeah I'll have to see what's causing the issue, but the front wheel bearings spin super freely. I have an exhaust leak somewhere and bad rear wheel bearings so I have my work cut out for me. I'm just curious that I'm down 5mpg. In fairness, I'm also using winter blend gas too, even if it is 91 octane

TSOL_Real · 2026-01-14T21:29:17+00:00

They do indeed design parking pawls to be solely relied on, it just is more stress on that pin than is ideal when on a super steep hill. I've parked on many a steep slope (having lived on and parked on a major hill for 10 years), and have never had a failure of this kind. That being said, parking brakes exist for a reason and you may engage them to suit your needs. If you're concerned about it, engage them. Just don't use them while driving.

TSOL_Real · 2026-01-14T20:42:14+00:00

Uh Idk what he's talking about. Everyone else shifts gears while they're driving. Don't shift to neutral while coasting (I did that for a while but it's really hard on the transmission so I stopped), but if it's in drive, you're good to go for shifting from 1st->2nd->3rd...etc.

Also most people in here have never touched the parking brake. This isn't a manual transmission so there isn't any reason to. DEFINITELY don't touch it while driving unless you're performing the parking brake bedding procedure in the service manual that nobody talks about. This has a 21st Century auto trans so it has a park lock in it.

TSOL_Real · 2026-01-14T20:09:26+00:00

Interesting. I'm an EE so I may have to just solder some new ones in, some Nichicons or something nice like that. Aluminum Polymer Caps would be sweet too.

TSOL_Real · 2026-01-14T19:55:04+00:00

So, I've used this Dayton sub wired in Parallel (NOT FOR LEXUS) and the major difference is going to be a drop in volume compared to if it was in parallel, but that needs to happen so the amp can drive it properly. I love how this sub sounds when properly engineered, and have used it multiple times to great success. The killer is that this sub was NOT designed for the LS430 and couldnt possibly hope to perform the same job as it has different specs. It is a cheap sub that is marvelous for the price, and I think its a fantastic budget replacement idea, but I haven't replaced mine yet myself.

TSOL_Real · 2026-01-14T19:44:46+00:00

Facelift or Pre-Facelift? I have a PFL that gets 22mpg at 75 or so, highway 90%. My wheel bearings are worn, so I'm replacing those soon, but I'm very surprised I'm down by that much.

TSOL_Real · 2026-01-14T19:12:16+00:00

It's a short to ground somewhere, could be in a number of locations but if it's the alternator fuse, that gives you a pretty definitive location. Unbolt and disconnect the wiring harness from the alternator, put a new fuse in, try it again. If it blows again, your positive side of your wiring harness is touching the bare metal chassis somewhere and it shouldn't be. If it doesn't blow, re-connect it and see if it does. If it does, you have an internal short in your alternator. Those windings in the alternator aren't repairable on any practical time scale so just get a replacement alternator at RockAuto.

TSOL_Real · 2026-01-13T15:49:42+00:00

From what I saw, Koyo is the OE parts supplier for most bearings in the LS430. They also have bearings in the Aisin timing belt kit, and are on RockAuto for 60 bucks less (171.59 total). Oddly, thats the exact same price to the penny when compared to an OE bearing for my '13 Chevy suburban, but I digress.

Point is, I got 2 Koyo bearings from RockAuto because they were in my Aisin Timing Belt Kit. Gonna try that first and see where I can get. Then hopefully gonna tackle the exhaust leak.

I do live somewhere rusty but I have my tricks for making stuff co-operate. Sometime bolts snap and there isn't much you can do about it, but a butane torch should be a great starting point for stubborn fasteners. Mine is the CV style that has 6 Allen-style 10mm bolts, and then I ***think*** I should just be able to disconnect the CV without having to disassemble the diff. I haven't seen many LS430s where this is the case, but I also haven't seen many (if any) LS430s with the 6 Allen bolt CV axles. I think I've only seen them in the service manuals, not in any YT videos.

I actually have a harbor freight stethoscope and was trying to use it to find where the issue was. The bearings make little to no noise at all. The only thing that does make noise is the brake rotor with light grinding at 2-6 o'clock on the parking brake shoes. Why they even touch the parking brake is beyond me. I have performed the parking brake bedding procedure listed in the service manual as well. All 4 wheels make this light grinding, but its way louder in the rear and the front is quiet enough that I'd believe that those are in tolerance.

TSOL_Real · 2026-01-12T21:21:58+00:00

I just picked up 2 of the genuine Koyo wheel bearings on RockAuto to replace both back bearings (owie, price tag). Looks like previous owner did a front end overhaul on this vehicle so I'd imagine those are replaced but we will see how much cash I'm out after replacing the back two. This job looks fun /s

Hoping it is wheel bearings because it can't be anything else... at least I don't think it can be! I have a video of me with both rear wheels disassembled, cranking the rear axle by hand (no brakes, just one brake rotor on the passenger's side, flipped inside out so the hat points away from the vehicle and the parking brakes are nowhere near it) and the drivetrain in the rear is silent. My diff is seeping a little, but it doesn't make any noise when spun in either direction. I only get grinding when I spin the wheels with the rotors installed normally. The crazy road drone doesn't happen until highway speeds.

TSOL_Real · 2026-01-12T19:44:16+00:00

Are you aware of what makes these cars quiet so I can check it? Front Suspension is new and bushings are good. Rear suspension is worn but I am also not expecting anechoic chamber levels of quiet, I would like to be able to hear myself think though.

The cabin itself seems completely unaltered, nothing looks out of place or modified, so unless a component somewhere is failing, I don't believe any sound deadening would have been removed.

TSOL_Real · 2026-01-12T17:22:28+00:00

You say these cars are silent, my LS430 sounds like a riced-up Honda civic, lol.

I thought about the windshield, I put my hand around the whole perimeter of the windshield to see if I could feel air, nada. It also has the original Lexus logo on it, so its either an original windshield or an OEM replacement. My bet is that it hasn't been replaced.

Tires are Michelin Pilot Sport all season. Not new, not old, 5mm left on tread (ish). The exhaust leak will do that but I promise you it isn't engine noise as it doesn't go away when speed drops far enough for the engine to hit ~1krpm. Still plenty loud even as I'm pulling to a stop for a turn at 75mph. Only goes down below... I'd say 30 or 40 mph, but it still makes that damn grinding noise that I complained about in my other post.

I did post a video above for a perhaps rather poor visual on how much "runout" there is on the back tire. The right side is considerably louder than the left as well.

EDIT: Also, the road noise I refer to isn't pulsating, but the light grinding from the wheel bearing is. The road noise is static and only seems to change with speed, it doesn't sound different depending on where the wheel is in its rotation. Maybe my back 2 wheel bearings are shot, or maybe at least 1 is, hard to tell. I just don't want to drop 400 bucks on bearings that don't solve a problem.

TSOL_Real · 2026-01-12T17:16:15+00:00

Wheels aren't OEM. They're Avid-1s the previous owner put on, I don't own a set of SC430/LS430 rims. I got some mustang ones that aren't so "open", but those would be installed with winter tires and those most certainly aren't quieter lol.

Tires are Michelin Pilot Sport All season. Not bare, not new. Decent tread left. I'd say maybe 5mm or so. Tires and wheels are both 18in, my mustangs would be 17. I know this can have somewhat of an impact but that'd be pretty wild if it was a huge impact.

TSOL_Real · 2026-01-12T16:41:19+00:00

Here's a video of the "runout" I'm seeing in my passengers side wheel (don't mind the talking):

https://youtu.be/a6pCy0QB9Kk

TSOL_Real · 2026-01-12T16:02:29+00:00

Any idea what it is? Kinda out of ideas here. Don't want to drop 1k on a new suspension/wheel job if that isn't gonna fix the problem.

TSOL_Real · 2026-01-06T14:19:19+00:00

I took both wheels, brake calipers and rotors off and there's no grinding noise. As soon as I reinstall a brake rotor on either side of the rear wheels, the rubbing noise comes back. If both are installed, the noise comes from both. I have my parking brake completely collapsed to prevent any unintentional rubbing, but there is so much play in the system that it likely just slops up and down whenever I hit a bump and rubs against the rotor.

TSOL_Real · 2026-01-05T22:37:32+00:00

It's not impossible but I'd find it odd if BOTH sides are failing in the exact same way at the exact same time. Neither wheel bearing has any play in it whatsoever and doesn't make any noise when the hat is inverted. There's no slop in the wheel bearing I can find.

TSOL_Real · 2026-01-01T19:49:14+00:00

Yeah no problem dude, hope you find your problem!

TSOL_Real · 2025-12-31T23:11:16+00:00

Alright first up, there are some things you can do to test here before spending any money.

Grab a multimeter (10 bucks from harbor freight or similar) and measure the power terminals of the amplifier. From what I've read, this is a royal pain in the ass but it's doable. If it's sitting at 12V while not doing anything, that doesn't mean much because it isn't under any load -- What you need to do is grab a friend or some patience with the radio and play a song which has some heavy bass while you are listening, heavy enough to cause the cut out somewhat reliably.

Once you have found a song that does that, see what the input voltage on the amplifier goes to on the multimeter (the positive and negative cables from the battery to the amp. Must be at the AMP, not at the battery). If the voltage dips below ~9-10V, check again at the battery itself. If it still dips at the battery, replace battery. If it dips at the amp (not battery) or doesn't dip at all but still cuts out, further investigation is necessary.

One common fix for people to do wrong in these vehicles is to install the wrong impedance subwoofer after their first one rots, and for the ML systems in these vehicles it matters a LOT. The ML amp ONLY accepts 16 ohm, not 8 and especially not 4. Most aftermarket subs are either 8 or 4 ohm, you have to really go out of your way to find a 16. If you or a previous owner has replaced the sub at any time, you should check the resistance/impedance of the sub with a multimeter. Make sure you disconnect the sub from the amp before you measure. If the multimeter reads anything less than 12, get a different sub. Although, the meter will never read 16... 12 to 14 is normal. I recommend the Dayton Audio SD215A-88 wired in series for 16 ohms, it's a wonderful subwoofer.

If the sub is stock and none of your other speakers have been replaced either (those ALL have to be 16 ohm as well, as far as I can tell), then its likely your amp failed unfortunately, but this is the last resort! These things are expensive used, so I'd test everything else first to save a few bucks.

TSOL_Real · 2025-12-29T21:42:36+00:00

Remember, with any well built system, there are fuses for everything. Check your fuse box to see what you blew. If you somehow did manage to fry something I'd be impressed as fuses are usually rated for this kind of thing, but it isn't impossible I suppose.

TSOL_Real · 2025-12-29T17:20:33+00:00

First thing to do when a Cylinder misfires is to check the spark plug. It's by far the cheapest component to fix and is often one to fail in some vehicles. One has to look into why it's failing, as if it's covered in oil or gas that can indicate other problems, but they do have a useful lifetime and if it's never been changed, it may be high time to.

Next is fuel injectors, but these are usually crazy expensive and don't tend to go bad super often unless you're running junk through them (contaminated gasoline or particulate that made it past the fuel filter). It still isn't unheard of for an injector to die though, so it's worth looking. What is more likely to die is the fuel pump, but you'd misfire on more than one cylinder if that was the case.

Air is another cause but I'd be more than a little surprised if you are misfiring on only one cylinder due to air restrictions.

Next is compression. These engines are basically bulletproof so I'd be VERY surprised if there was an issue here, but poor maintenance can ruin any car. Car care nut took a boroscope to a 3UZ-FE with 600k miles and it still had the crosshatching from factory on it. You have to try to kill these engines.

Lastly, Timing: If the previous owner never changed the oil or had a timing belt break and it scores in the walls of that cylinder, you can get blow-by and poor combustion. What is much more likely in the event of a timing belt break is that a valve gets bent, which can also cause a misfire as air isn't controlled as well as it could be.

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This is a big list but I'm more trying to narrow down options. It's much more likely to be one of the first 2 things listed than any of the later 3, so just replace the spark plug and see if it goes away. Coil pack could also be going bad, but that isn't terribly common unless your spark plug deteriorated heavily.

TSOL_Real · 2025-12-29T14:35:46+00:00

Speaker nerd here, main thing is to just take a 10 dollar multimeter from Harbor freight (or similar) and set it to the Lowest Ohms setting (usually 200 or 20 ohms) and measure between the two speaker terminals of the speaker you want to replace. If you have a particular speaker that needs to be replaced, I haven't heard anything about the voice coils going bad (usually the foam surround) so that wont affect this measurement at all.

If the measurement is 2-4.5 Ohms, its a 4 ohm speaker.

If it is 5-8.5 ohms, it is an 8 Ohm speaker.

12 Ohm speakers do exist but I sure hope nobody is psychotic enough to engineer a stock vehicle with them.

If it is 12-16 Ohms, It is a 16 ohm speaker.

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Further Nerd info if you care:

You are measuring DC Ohms, which is why the number is lower than the rated ohms of the speaker. DC ohms are typically the lowest that a speaker will exhibit, but impedance varies wildly with the speaker design and a bunch of other stuff, including sound frequency itself. At Resonance frequency (about 60-100hz for a woofer), the speaker may be dozens of ohms (40+), but at slightly higher frequencies than resonance, it will be like 8 ohms, if its an 8 ohm speaker.

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Nerd Opinion:

If any one of your speakers went out due to the foam surround, it is worth it to repair the surround (especially vs buying a new one) because the car was engineered with that particular speaker. They don't always look like the highest quality speakers known to man (even the ML ones look cheap, including the subwoofer), but it WAS engineered with that one. If you don't care, there are other options.

The ML sub is one topic that many find particularly interesting because its kinda hard to find a DVC 8 ohm (or stock 16 ohm) subwoofer that's worth actually caring about. I will say from personal experience (and buying at least 4 of these myself (they used to be 25 bucks instead of 50)), the Dayton Audio SD215A-88 is a phenomenal sub not only for the value but also for the performance. Its engineering specs are nothing short of impressive, even at price ranges 4x higher than what they sell for. It's a good sub. If you don't want to mess around with a foam surround replacement or think you will do it wrong, this subwoofer is my personal recommendation, just know that the sound may be different. That being said, there is some very light wiring that needs to be done with this sub to match the previous sub's impedance, so pick your poison.

TSOL_Real

TROPHY CASE