When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I've been lurking these forums for while trying to get some insight into what could be causing a power drain on my sons ES300 while it's running. I initially swapped a battery and an alternator to no avail. Following some discussions in other threads it seems that the stock 80amp alternator is underpowered for this vehicle. I picked up an RX300 alternator which should work according to the discussion in these threads which has been modified to pump out 130amps.
I ordered some 4 gauge cable which I'm going to run a new wire from the alternator to the battery, and I'm going to run new grounds to the chassis and the engine block. I'm hoping this will fix the voltage from dropping to non charging levels.
And here's another problem. I went to pull and reseat the 100amp alternator fuse and the entire casing pulled out and left the legs stuck in the box, and the fuse is toast. I soldering some solid copper wire to the legs and resoldered the fuse part across to each copper wire and so far, it's holding and supplying power as it was originally.
My question: If I run a new power wire from the alternator to the battery and connect an inline fuse at the battery, will that work without the need for that fuse I just broke?
Any issues with using that 130amp alternator in this car? Any advice on what other wires I can check or replace?
I would really suggest Against any intrusions to the Factory Systems, they are designed specifically for those cars and don't need any alterations. I myself have had a 130A Alternator in my 2000 ES300 for at least 2 years at this point, and neither the Factory B+ Wire, nor the 100A Fuse have ever given me any issues. Not to mention that the 4AWG Wire you purchased for a retrofit is considerably Smaller than the one Already installed in your car from the Factory.
Here is a thread about the Alternator B+ Wire. In short, all that matters is the Car's Current Consumption, not the Alternator's Rated Power, you can have a 300A Alternator in there, it won't change the fact that the car is Unable to draw That much Current at once, it simply doesn't have enough Electrical Components to do so, ergo the Wire that is currently installed in your car is already sufficient for the Power Demands of your car, and unless you are planning on installing an Aftermarket System with a huge Power Demand, you should leave the Factory B+ Wire intact, same goes to the 100A Main Fuse.
Other than that, the Battery in those cars is Secondary, the B+ Wire goes from the Alternator Directly to the 100A Main Fuse, the Battery is connected in Parallel to the Fuse Box with a pretty small Wire that is just enough to run Basic Components while the Engine is Off, it is also what Charges the Battery while Driving, here is a thread that shows said Wire. The other, Bigger Wire coming to the Positive Battery Terminal is running directly to the Starter, it does not go anywhere else, it's literally about 50cm long.
As for the Ground Leads, that is indeed the point that leaves a lot to be desired in those cars, and I did make my own Ground Leads to the Battery, as well as between Engine and the Frame, and I did use a 4AWG Welding Wire, it is a Lot more Flexible than regular wire you can buy at the store, not that I have noticed any improvement, the car didn't start producing gas instead of consuming it after that, but at least I can now sleep better knowing that I won't have any Grounding Issues in the Future.
The fact that your 100A Fuse managed to crumple apart like that is alarming all on its own, Factory Fuses are extremely reliable, there is a good chance someone else has been in there and replaced it with an Aftermarket piece, never trusted them before, and never will, here is a thread on what happens if there is a Loose Contact on that Fuse. The Part Number for the Factory Fuse is 90982-08246, below is a video on how to replace it, do so and see if the Battery will start Charging Normally.
I would really suggest Against any intrusions to the Factory Systems, they are designed specifically for those cars and don't need any alterations. I myself have had a 130A Alternator in my 2000 ES300 for at least 2 years at this point, and neither the Factory B+ Wire, nor the 100A Fuse have ever given me any issues. Not to mention that the 4AWG Wire you purchased for a retrofit is considerably Smaller than the one Already installed in your car from the Factory.
Here is a thread about the Alternator B+ Wire. In short, all that matters is the Car's Current Consumption, not the Alternator's Rated Power, you can have a 300A Alternator in there, it won't change the fact that the car is Unable to draw That much Current at once, it simply doesn't have enough Electrical Components to do so, ergo the Wire that is currently installed in your car is already sufficient for the Power Demands of your car, and unless you are planning on installing an Aftermarket System with a huge Power Demand, you should leave the Factory B+ Wire intact, same goes to the 100A Main Fuse.
Other than that, the Battery in those cars is Secondary, the B+ Wire goes from the Alternator Directly to the 100A Main Fuse, the Battery is connected in Parallel to the Fuse Box with a pretty small Wire that is just enough to run Basic Components while the Engine is Off, it is also what Charges the Battery while Driving, here is a thread that shows said Wire. The other, Bigger Wire coming to the Positive Battery Terminal is running directly to the Starter, it does not go anywhere else, it's literally about 50cm long.
As for the Ground Leads, that is indeed the point that leaves a lot to be desired in those cars, and I did make my own Ground Leads to the Battery, as well as between Engine and the Frame, and I did use a 4AWG Welding Wire, it is a Lot more Flexible than regular wire you can buy at the store, not that I have noticed any improvement, the car didn't start producing gas instead of consuming it after that, but at least I can now sleep better knowing that I won't have any Grounding Issues in the Future.
The fact that your 100A Fuse managed to crumple apart like that is alarming all on its own, Factory Fuses are extremely reliable, there is a good chance someone else has been in there and replaced it with an Aftermarket piece, never trusted them before, and never will, here is a thread on what happens if there is a Loose Contact on that Fuse. The Part Number for the Factory Fuse is 90982-08246, below is a video on how to replace it, do so and see if the Battery will start Charging Normally.
Thank you for your reply and input. So basically leave the power wires alone from the alternator since they are already capable of sending enough power to the battery and just rerun the two grounds correct?
Also, appreciate the part number and the video on replacing the fuse. Any issue leaving the 100amp vs using a larger one like a 120amp?
He's gotten a couple of dead starts and voltage is all up and down when the car is running, so the alternator isn't providing enough voltage to charge while running. The old alternator did the same thing although it didn't leave him stranded with a dead battery. I replaced both alternator and battery back in October, so I'm wondering if the alternator is toast and if something in the wiring caused it. I see the biggest drops when the AC and the headlights are turned on, so wondering if a weak ground somewhere is the culprit. Today I'll do a load test on the battery also just to make sure it's still good. My main concern is that the weak voltage conditions trigger the ABS lights to come on and Traction control light to flash. He's a student driver and I'm concerned for him driving without those safety options.
Load test is fine on the battery. Maybe the alternator can't keep up with the power demands of the car. Seems good at start showing over 14v, but driving around for a while it ends up dropping down to the 12v range, and if the battery is weak, into the 11v range.
Figured I'd share my fuse job Frankensteining it for now till the replacement fuse comes in.
Sounds like a bad alternator. Rebuild that one with a proper VR board, or exchange for a better one. A failed VR board will also usually leak A/C voltage, you could check for that tell-tale sign, too.
off-brand and many Auto Parts store rebuilds have HORRENDOUS VR failure rates. I went through four from O’Reilly until I just got my money back and got a better one at NAPA. It was the ONE alternator I did not rebuild myself at the time because we were in a hurry. Huge mistake.
Sounds like a bad alternator. Rebuild that one with a proper VR board, or exchange for a better one. A failed VR board will also usually leak A/C voltage, you could check for that tell-tale sign, too.
off-brand and many Auto Parts store rebuilds have HORRENDOUS VR failure rates. I went through four from O’Reilly until I just got my money back and got a better one at NAPA. It was the ONE alternator I did not rebuild myself at the time because we were in a hurry. Huge mistake.
You're right about that. This is definitely a part that's finicky with this car. I picked up this one so I'm hoping it's strong enough to provide for the power demands of the car.
Just an update. I put the 130amp alternator in this weekend, replaced the stock battery terminals with Schumacher Zinc Terminals and fixed the broken fuse replacing it with the 100amp stock fuse. I charged the battery up before running the car, wasn't too bad with about 70% capacity based on what the charger started at. My son has driven it a few times and hasn't seen any voltage drops. Voltage seems to hang in the high 13v area with AC and headlights on.
I've got some 2awg welders wire coming in today with crimp connectors so I can upgrade his ground cables if need be. I noticed that the body (looks like it's on the trans body) and chassis wires merge into the one on the battery terminal. I also checked for voltage drop from the alternator B+/body to the battery +/- and only saw a .02 drop.
I'm hoping it was just an original alternator failure that didn't get solved with the aftermarket rebuilt one. The one that is in there now is a rebuilt Denso for the RX models that normally provides 100amps but has been modified to provide up to 130amps. Overkill, I know but the price wasn't that far off from getting an unmodified 100amp unit or an original 80amp Denso rebuild.
Unfortunately, even with a stronger alternator the car is back down to showing low voltage and triggering the Traction Control and ABS lights. I'm gonna upgrade the ground wires next but I'll be out of ideas on what or where the problem is stemming from.
Here is a thread on how to diagnose No Charge condition.
When the Engine is Running, check the Voltage between the B+ Terminal of the Alternator and the Alternator Frame, do not put the Lead on the Nut of the B+ Terminal, attach it Directly to the Threaded Stud, and see if it is the same as the Voltage you have between Positive and Negative Terminals of the Battery.
If both voltages are the Same, then you either have another Fried Alternator, or the Signal coming to the Voltage Regulator is Missing, the thread linked above describes the function of each wire on the Voltage Regulator, and how to check them.
If the Voltage on the Alternator is Higher than on the Battery, then you have a Break in the Connection between the Alternator and the Battery. Again, the thread above describes how to find said Break, that was, in fact, the cause of the issue from that thread, a B+ Wire was Loose inside the Fuse Box, sorry for spoiling all the fun..
Here is a thread on how to diagnose No Charge condition.
When the Engine is Running, check the Voltage between the B+ Terminal of the Alternator and the Alternator Frame, do not put the Lead on the Nut of the B+ Terminal, attach it Directly to the Threaded Stud, and see if it is the same as the Voltage you have between Positive and Negative Terminals of the Battery.
If both voltages are the Same, then you either have another Fried Alternator, or the Signal coming to the Voltage Regulator is Missing, the thread linked above describes the function of each wire on the Voltage Regulator, and how to check them.
If the Voltage on the Alternator is Higher than on the Battery, then you have a Break in the Connection between the Alternator and the Battery. Again, the thread above describes how to find said Break, that was, in fact, the cause of the issue from that thread, a B+ Wire was Loose inside the Fuse Box, sorry for spoiling all the fun..
Hope this helps and best of luck!
I checked those all several times before and after each alternator change, the values were pretty consistent. I'll check again tomorrow. What I haven't tested is the the plug going into the alternator. I replaced the fuse and I made sure the screws were tight. Those ends looked fine as well. Aside from replacing the three prong connector with a new one, I'd like some more info on where they terminate at so I can check those ends as well.
Are those Values consistently Identical on the Battery and on the Alternator?
It's not about the General Check, per say, it's about the Difference between Alternator Voltage, and the Battery Voltage, if your Alternator is showing proper 13.5 - 14.5V, but you only have 12V on the Battery, then you will know for sure that there is a Break in the Connection between the Alternator and the Battery.
Are those Values consistently Identical on the Battery and on the Alternator?
It's not about the General Check, per say, it's about the Difference between Alternator Voltage, and the Battery Voltage, if your Alternator is showing proper 13.5 - 14.5V, but you only have 12V on the Battery, then you will know for sure that there is a Break in the Connection between the Alternator and the Battery.
Hope this helps and best of luck!
They've consistently shown the correct voltage, both at the alternator and at the battery. The voltage jumps all over the place one minute showing charging, the next it shows in the 12v range, and then it'll drop into the 11v range. That triggers the abs/tc warning lights to pop.
You saw in the one pick the voltage was 11.9v. This pic was taken a little bit afterwards. It's back up to 13.8v. I'm wondering if the battery is having trouble charging at that voltage and because it's not fully charged, it's causing the voltage drops below 12v. That battery was fully charged off battery charger when that alternator was put in. So either something in the electrical system is preventing it from getting charged properly or the battery is a dud. I did a load test and it measured good.
1999 Power Issues
