ttnguyen23

I can access into the main fuse box but I do not see how to get inside the box.
I wonder 140A and 100A fuses can be pull out or unless they bolted down that I need to dissemble the fuse box?

JoeInHNL

I believe that the terminal labeled + goes to the alternator, and if there is no voltage on the terminal then the alternator fusible link is blown. You can confirm this by checking for continuity between the + terminal and the alternator output terminal.

The fusible links are held in by screws. It requires some disassembly of the fuse box to access the screws. Looks to be doable but very fiddly to replace the links.
The fusible links look similar (but not exactly) like this:

Fusible links blowing when battery polarity is reversed is very common. I think you have found the problem (or at least part of it).

05RX330AWD

I imagine that's the reason why some try to find alternatives, install a breaker that is easily accessible, if an issue occurs, press a button, your good to go.
Never went through this myself although JoeInHNL is correct, doesn't appear to be a simple DIY.
Hopefully a CL Member who went through this issue can chime in.
I'm thinking about installing a breaker as a preventive measure.

ttnguyen23

I think you are right. The pictures are seem to be a 140A and 100A. I need to access to it to check it out and replace as necessary. I need to get the car start. Problem do not know how to get to these fuses.??????

ttnguyen23

I really like this idea to add breakers instead go thru the problem that I had.
Right now I just need to make the car start and no fix any other problems caused by reversing the battery polarity.

ttnguyen23

Run good continuity test from starter + terminal to battery +terminal cable.
I need to do the same thing to generator. May be tomorrow.

ttnguyen23

I work on main fuse box. See some tabs around the fuse box. Cannot figure out how to disassemble the box yet. I will try do some more research on youtube tonight.

DennisMik

A fuse provides better protection than a circuit breaker. This is because the circuit breaker takes at least twice the time to "trip" as it does for a fuse to "blow", subjecting the equipment to longer periods of short circuit situations. This is of importance when you are trying to protect electronics.

05RX330AWD

Agreed, although that could also depend on which breaker is chosen to do the job, I would prefer to install a breaker with good odds that it will protect the fuse from blowing.

DennisMik

If you install a circuit breaker in series with a fuse, the fuse will still blow before the circuit breaker trips even if you use an "A" category circuit breaker. If the fuse was in the slo-blow category, maybe not, but slo-blow fuses are generally not used in cars.

Circuit breakers have a letter that represents the reaction time for how fast it will trip. The letters used are A B C and D. When you look on the circuit breaker (or the spec sheet), the letter will be after the number that is the amperage rating. For example, a 15 amp circuit breaker could have 15A or 15B or 15C or 15D on it. If you were looking at the fast trip 15A breaker, many people assume that the A means amps.

The reaction time rating is not so much of a time factor (but it is a part of it), it is a current factor. The A category has a range that starts at 10 times the rated current amount and goes to some amount that I forget. Then the B category range. The D category trip range is several hundred times the rated amperage.

ttnguyen23

Well explain.
I still thinking two bad designs in car industry is use inline cable fuse and hard to replace the fuses. I do not see why? That is very basic engineering practice. Anyone agree?

05RX330AWD

Totally agree, although why? Lexus wants you to pay them a visit, $$$ an hour, instant revenue from poor design & consumer frustration.
Same goes for how well the rear spark plugs are hidden.

DennisMik

Welcome to the Detroit philosophy of automobile design - Make it look pretty. So what if it doesn't work.

ttnguyen23

It took a few hours to looked at around the fuse box and bottom.Found a few tabs about haft way around the fuse box. Use long think flat screw driver unlocked these tabs.
From top of the inside box have another tab near 100A and 140A fuse. Unlock the tab with long flat screw drive and slow push entirely the fuses assembly down. work on this steps four or five times until these fuse are push down from the fuse box. Found 4 screws to hold the fuses to their own housing. Carefully notice somes wire connected to the screws. Remove the wires.


Now I can pull out these big fuses, 140A and 100A, have long male terminals are hold to their own assemble female housing.


Went to Toyota got the fuses. Found the price are half comparing to Lexus .


I guess I will stop today and go to play golf.


Will continue to install new fuses and assemble the fuse box, checkout the wiring of the alternator and do some voltage check before start the engine.

05RX330AWD

Good to hear you made some progress , check the alternator afterwards to be sure it is charging correctly (should read 14+V), hopefully no diodes were damaged.