r32 gts25 Main fuse blowning

[Prof_Finesser]

I was working on the car last night finishing up a battery relocation and when I flipped my breaker my dash and most of the interior power was gone.  So I searched the fuse boxes and found that the main fuse blew so I thought it was just a blue moon type of deal.  I bought another one and it blew.  Does anyone know what that fuse powers besides the interior fuse box its a 75a grey and clear top.  I've read some forums but not much info but some said about it grounding off the alternator so I'll put some pics of the wiring on the ALT.  This is on a new built engine so it hasn't been ran yet I'm almost done and very close to starting.

[GTSBoy]

Are you seriously doing this without having the car's wiring diagram? It's freely available on the internet. I even made the best resolution scans I could and posted them on this very forum a year ago or so.

[Prof_Finesser]

9 minutes ago, GTSBoy said:

Are you seriously doing this without having the car's wiring diagram? It's freely available on the internet. I even made the best resolution scans I could and posted them on this very forum a year ago or so.

Yea I seen the post but its for a 33 not a 32.

[Duncan]

well, yes the alternator is the easiest place to get that wrong; check the wire with continuity to battery + is on the alternator + and the alternator earth is correctly to chassis earth

[GTSBoy]

6 minutes ago, Prof_Finesser said:

Yea I seen the post but its for a 33 not a 32.

I realise this, but...... it's still useful. Simple things like what the main fuse runs and what the wiring near the alternator looks like don't tend to change much. Notwithstanding that, the R33 drawings are out there too.

[Prof_Finesser]

6 minutes ago, Duncan said:

well, yes the alternator is the easiest place to get that wrong; check the wire with continuity to battery + is on the alternator + and the alternator earth is correctly to chassis earth

I checked it rn and no power is going to the alt.  Doesn't the main fuse send power to it?

[GTSBoy]

Oh, and check your thread title - that was the initial source of the confusion. I already knew you were working on an R33, but the mention of R32 derailed my thinking.

[GTSBoy]

Just now, Prof_Finesser said:

I checked it rn and no power is going to the alt.  Doesn't the main fuse send power to it?

Get a wiring diagram before you set fire to it.

[Prof_Finesser]

1 minute ago, GTSBoy said:

Get a wiring diagram before you set fire to it.

Lol I’m trying all I can find is the ones u posted

[Murray_Calavera]

10 minutes ago, Prof_Finesser said:

Lol I’m trying all I can find is the ones u posted

I have a Christmas gift for you. 

R33_Wiring_Diagram.pdf

[Prof_Finesser]

11 minutes ago, Murray_Calavera said:

I have a Christmas gift for you. 

R33_Wiring_Diagram.pdf 20.07 MB · 1 download

Yes I know there is that one but it doesn’t really have info on the main fuse 75a which I believe is not on the 33.  

[GTSBoy]

8 minutes ago, Prof_Finesser said:

but it doesn’t really have info on the main fuse 75a which I believe is not on the 33

Wot? This one?

[Prof_Finesser]

3 minutes ago, GTSBoy said:

Wot? This one?

oh yea I'm dumb.  I'm getting another fuse tomorrow and will check it after work I looked at it rn and the positive to the alt was pretty loose and the ground was good not sure if the pos being loose will make the fuse blow or not.  In the diagram everything looks whats on mine.  I read another forum on my ALT there is not rubber piece on the pos terminal do you think its grounding on the ALT since it touching?  In the other forum he said he just put a rubber washer and it fixed the issue.

[GTSBoy]

1 hour ago, Prof_Finesser said:

and the positive to the alt was pretty loose and the ground was good

If there's no short to earth then there shouldn't be a reason for a loose terminal to cause the fuse to blow.

1 hour ago, Prof_Finesser said:

I read another forum on my ALT there is not rubber piece on the pos terminal do you think its grounding on the ALT since it touching?  In the other forum he said he just put a rubber washer and it fixed the issue.

Well, obviously the + lead can only touch the thing that it is supposed to touch on the alternator stud. There really shouldn't be an easy way to short the + lead to the alternator body. There is supposed to be an insulating washer on most B+ studs (and on the D+ also). See below

[Prof_Finesser]

22 minutes ago, GTSBoy said:

If there's no short to earth then there shouldn't be a reason for a loose terminal to cause the fuse to blow.

Well, obviously the + lead can only touch the thing that it is supposed to touch on the alternator stud. There really shouldn't be an easy way to short the + lead to the alternator body. There is supposed to be an insulating washer on most B+ studs (and on the D+ also). See below

yea both of my washer are gone i will get some tomorrow and try the new fuse

 

[Duncan]

before you pop another fuse or 10, check if there is continuity between earth and the fuse socket. If there is, you need to trace through that loom and find the massive short.  You didn't just get 2 unlucky bad fuses all of a sudden.

Edit, on second check it is clear that the positive wire's terminal is touching the alternator body in your pic. You don't really need an insulating washer, just screw the existing nut down to the body (tight but not overtight) then fit the ring terminal, then another nut to hold the terminal. That will keep the terminal well off the body. 

And yes, adding a boot is good practice anyway, it will stop big sparks if you are working in that area without the battery disconnected and accidentally touch the terminal and anything else with a tool

[Prof_Finesser]

22 minutes ago, Duncan said:

before you pop another fuse or 10, check if there is continuity between earth and the fuse socket. If there is, you need to trace through that loom and find the massive short.  You didn't just get 2 unlucky bad fuses all of a sudden.

Edit, on second check it is clear that the positive wire's terminal is touching the alternator body in your pic. You don't really need an insulating washer, just screw the existing nut down to the body (tight but not overtight) then fit the ring terminal, then another nut to hold the terminal. That will keep the terminal well off the body. 

And yes, adding a boot is good practice anyway, it will stop big sparks if you are working in that area without the battery disconnected and accidentally touch the terminal and anything else with a tool

I checked it today the one prong had power and one didn't so I think its fine there or if your saying to check the ground that comes off the alternator both had no power.

[GTSBoy]

42 minutes ago, Prof_Finesser said:

I checked it today the one prong had power and one didn't so I think its fine there or if your saying to check the ground that comes off the alternator both had no power.

What he was saying is check for continuity to EARTH at the fuse box. If one side is power and the other side is continuous to earth, then when you put a fuse in, you have a short circuit (where you really really shouldn't).

[Prof_Finesser]

23 hours ago, GTSBoy said:

What he was saying is check for continuity to EARTH at the fuse box. If one side is power and the other side is continuous to earth, then when you put a fuse in, you have a short circuit (where you really really shouldn't).

Wasn't able to get to it today also have some washers coming tomorrow will update tomorrow 

[Prof_Finesser]

I got to it today and bought some rubber washers and it fixed it I did check the continuity first Duncan thank you guys for the info I kinda learned a lot from this about electrical stuff thanks.