Accidentally Switched Battery Polarity

w1427486 · September 3

I accidentally switched Battery polarity on my car and now it wont start. The dash lights up and the car wont crank.

I have checked the fuses and some 30A had to be replaced as they were bad.

What could the issue be?

madasahatter · September 3

Have you checked this fuse.It is the long strip .

Linas.P · September 3

Yes - as above, combination fuse is the most likely thing to blow first... if you lucky... if you not lucky your car is totalled. And I don't mean it lightly, if combination fuse did not blow, but instead it damaged ECUs or wiring somewhere (which is like 50/50% chance), then likelihood of ever finding and fixing the issue is small. These cars have a lot of wiring and a lot of electronics that really really hates to be connected wrong way.

w1427486 · September 3

30 minutes ago, madasahatter said:

Have you checked this fuse.It is the long strip .

The fuse bar has 0 voltage from the screw.

madasahatter · September 3

Can you put some pictures of your fuse box.

w1427486 · September 3

39 minutes ago, madasahatter said:

Have you checked this fuse.It is the long strip .

Ok

Linas.P · September 3

So that would be main 140A (if memory serves... or 150A) link that has burned. Literally the last and thickest tab closest to the screw...

Should look something like this:

w1427486 · September 3

2 hours ago, madasahatter said:

Have you checked this fuse.It is the long strip .

And it is meant to be joined together?

Linas.P · September 3

yes - the picture is of the blown one.

w1427486 · September 3

To confirm it looks blown at 150a the beginning and where do I get this new part for cheap?

Lexusjim · September 3

this previous thread may be of help.....

Linas.P · September 3

I paid something like £50 from Amayama, from Lexus in UK it is £188... and there are no aftermarket options.

https://www.amayama.com/en/part/toyota/8262030170

https://lexuspartsdirect.co.uk/product/lexus-is-phase-2-fusible-link/

madasahatter · September 4

I bought mine from a diesel scrap car, just less wires than mine. Took plenty of photos,& put

which colour goes where. Took two of us about an hour and a half, fuse box keeps trying

to close on itself. if memory serves me right bought from upullit York £22.00.

Linas.P · September 4

Yeah it is painful piece of work, cables are short and tabs are hard to unlatch, be the time you unlatch one side the other pops back in, so it is constant fight and also you can't use too much force, because breaking it is not an option either. Having 6 hands certainly helps!

To be fair I have few of these lying around, so could sell for maybe £20, but I will not be around for few weeks... so that will have to wait.

w1427486 · September 4

1 hour ago, Linas.P said:

Yeah it is painful piece of work, cables are short and tabs are hard to unlatch, be the time you unlatch one side the other pops back in, so it is constant fight and also you can't use too much force, because breaking it is not an option either. Having 6 hands certainly helps!

To be fair I have few of these lying around, so could sell for maybe £20, but I will not be around for few weeks... so that will have to wait.

Can you get one to me somehow this week?

Linas.P · September 4

Sadly not, literally on my way to airport now and I have left the parts in Birmingham where I am swapping IS250 engine, not going back there until ~25th September.

Unfortunate timing, was there last weekend.

madasahatter · September 4

You could bridge it as a tempory repair. I used a washer bent in half and wedged in.

w1427486 · September 4

Would it not explode? or dangerous to solder?

madasahatter · September 4

The metal does not soldier, it is like a tin. provided you do not mess your Battery again it

should be fine. If you have some one handy, put a screw driver across the brakeage button

in the car should go green if so it will start. As soon as you stop you would have to keep doing it.

I run mine ages like that till i got the fuse link, there is a couple on eBay £120.00 each.

They are a pig to fit, so be forwarned. If i remember the triangle piece comes off first, it slides

in. If you have the replacement part practice taking it apart, then double the pain taking the old

one out and putting the replacement back in.

Linas.P · September 4

9 minutes ago, w1427486 said:

Would it not explode? or dangerous to solder?

It would not be advisable, as you bypassing the fuse, but may work as short term solution. I have pressed thick solid coper wire there just to check that my issues is certainly that, before ordering the new part. You can certainly take little piece of wire to bridge the gap and solder it, but then it is anyone's guess what amperage it could handle... it may blow at 50A just driving around (not ideal), or not blow at 200A setting the car on fire (also not ideal).

The only problem with soldering is that it will be very hard to access, but in principle doable as temporary fix.

madasahatter · September 4

I had no issues with mine just kept checking it, as its only a temp fix. It is up to the individual

wether they are stuck or not. I worked nights finished early hours, so needed my car.

w1427486 · September 4

i need help the bolt is like hard near the fusible link or stuck what do you recommend n

Herbie · September 4

5 hours ago, madasahatter said:

You could bridge it as a tempory repair. I used a washer bent in half and wedged in.

As a time-served and fully qualified electrician, that statement fills me with horror!

Fuses are designed as the weakest link in the chain and when excessive current flows the fuse is designed to 'blow' in order to protect the wiring and devices downstream. I have no idea what the current carrying capacity of a washer would be but I'll bet it's more than the wiring downstream that it's supposed to be protecting.

This means that if there is a fault then the wiring will heat up, the insulation will melt and cause short circuits, more than likely leading to a fire.

Do you really want to risk it :surprise: