Anybody know what this is?

[stevet]

Picked up my new to me GS300 today and noticed that cover over a relay box won't close properly due to whatever it is in the attached picture. Any clues as to what it is?

[Farqui]

Wow, that a big fuse. It must be as it says 'mega'!

Does the car have an aftermarket stereo or amplifier fitted?

[Britprius]

I could be wrong but that looks like someones attempt at a cheap way of repairing the ribbon fuse that runs along the side of the relays just visible in the picture. The blown fuse has had wires soldered on either side and connected to the new block fuse.

The fuse usually blows if a reverse polarity jump start is attempted.

John.

[stevet]

30 minutes ago, Britprius said:

I could be wrong but that looks like someones attempt at a cheap way of repairing the ribbon fuse that runs along the side of the relays just visible in the picture. The blown fuse has had wires soldered on either side and connected to the new block fuse.

The fuse usually blows if a reverse polarity jump start is attempted.

John.

Hi John. Yes you are right. Had a further investigation and it looks like someone has done repair on the Fusible Link by soldering in one big fuse. Going to leave it for now as it looks a big job to change it.

[Britprius]

2 hours ago, stevet said:

Hi John. Yes you are right. Had a further investigation and it looks like someone has done repair on the Fusible Link by soldering in one big fuse. Going to leave it for now as it looks a big job to change it.

Yes Steve the fuse is a bugger to change. I did one on a Prius for a friend, and it required the removal of the fuse/relay box to get at it from underneath.

John.

[Upex]

175 amp is a lot, should it be that big? Or is the normally fitted link lower in capacity?

Regardless, that wire doesn't look man enough to take 170amp, unless the sizes deceiving in the pic!

[Britprius]

On 9/14/2017 at 6:43 AM, Upex said:

175 amp is a lot, should it be that big? Or is the normally fitted link lower in capacity?

Regardless, that wire doesn't look man enough to take 170amp, unless the sizes deceiving in the pic!

The link fuses are not marked with the fusible ratings "this is only shown on the circuit diagram" as effectively the link is a series of fuses getting lower in rating as you go along the strip. From memory the first section in the Prius was rated at 120 amps so the GS could be higher, but it is doubtful it's normal running load is anywhere close to this. 

The cable from the Battery in the boot to the front of the car is not very large, and on some vehicles is made of aluminium instead of copper. However it only carries accessory loads or charging current not having to carry starter motor current. Doing some extensive testing on the Prius charge currents of over 80 amps is possible under certain conditions so again on the GS this could be as high as 100 amps this in spite of the fact that a label on the OEM Battery says "Maximum charge rate 5 amps".

John.

[Upex]

That pic looks to me that the fuse has been added with a maximum cable of 6mm2 csa, so if it's rated at 50 amp, it's doing well. My betting, the crimp and or cable will blow far before a 175 amp fuse!

If it were me, I'd be changing that out sooner than later. Likely to not see that current, but it has fire risk all over it to me.

[stevet]

Just an update on this. Lexus had a look while it was in for a service and recommended getting it fixed properly ASAP. I knew it was a botch job but thought the cost would be epic. Anyway not too bad as the fusible link is £94 and £115 in labour to change it. Booked in next week to get it done.

[Upex]

It's a good chuck of cash for such a thing, but, it's worth it, as that was most definitely a fire risk if even had to handle 1/3 of that fuse current for any amount of time.