VN LS1 melting fuses in the engine bay panel

[savage1987]

developed quite a problem with melting its underbonnet fuses.. not blowing the fuses, just melting them and the housings.... wtf could cause this?

fuel pump, engine fan, headlights and high beams all melted badly the other night. I'm guessing an earth somewhere(??) but somebody clued up in electronics pleeease give me some ideas. I'm lost with it.


I've had a few ideas so far..


1. engine swap to LS1 has no dedicated earth from engine to chassis - only earths via starter harness-->neg terminal-->body.
2. neg terminal-->body earth is ****, it's a bit of (thick ish) speaker wire. would this cause the problem?


I thought it was just because I was running an uprated fuel pump (Walbro 255lph) on stock wiring, and AU thermo fans also on stock wiring (although they are on an inline fuse instead of the blade becasue that got bloody hot from the massive draw the fans put on the system..)

HOWEVER

the headlights and high beams melted theirs also, the high beams worst of all. They are totally stock systems.



The headlights and high beams also went out the other night for no reason, only once in a couple of hours' driving, and only for a second, but they did go out, so I don't know what the hell is going on there.



Help appreciated, I don't want to go tearing **** apart and rewiring things unless I have to, I have minimal time to sort this out as I have a 4000km trip coming up in a couple of weeks and do not feel like getting stuck on the nullarbor would be particularly awesome.


Thanks
Sam

 

[savage1987]

this sort of thing but it's worse now

 

[savage1987]

Installed an earth lead from the engine block to the body of the vehicle and this seems to be fixed



Now I need to figure out why my thermo fan fuse blows

 

[db_notso]

discconect your fans from power and earth as close as you can to the battery (where you wired them and
then with a multimeter on ohms test for a short to ground on the wiring of the fans
so like from wire (from fans) with red lead (of ohm meter) and black lead (of ohm meter) to battery negative..
if it shows a connection you have to trace the wires till you find it
be aware that the wiring for the fuse could also be melted if incorrect fuse used (see below)

as for melting fuses normally this is either dodgy fuses or incorrect amperage fuse like a 40 instead 15

if the fans had huge current draw greater than fuse and blew the fuse
and then you fitted bigger amperage fuse then the wiring has not been upgraded
as the wiring will only be strong enough for standard amount of amps and so melt wires before heating fuse and casing melting it
suggest using a relay to power fans straight from battery and use the fuse to switch the realy so they operate like normal

hope this helps...

 

[savage1987]

discconect your fans from power and earth as close as you can to the battery (where you wired them and
then with a multimeter on ohms test for a short to ground on the wiring of the fans
so like from wire (from fans) with red lead (of ohm meter) and black lead (of ohm meter) to battery negative..
if it shows a connection you have to trace the wires till you find it

This was pretty much my plan, but substitute "multimeter" with "test leads hooked directly up to the battery".. if the fans turn on, there's probably no short. If they don't, there is (I don't have a multimeter)

be aware that the wiring for the fuse could also be melted if incorrect fuse used (see below)

as for melting fuses normally this is either dodgy fuses or incorrect amperage fuse like a 40 instead 15

if the fans had huge current draw greater than fuse and blew the fuse
and then you fitted bigger amperage fuse then the wiring has not been upgraded
as the wiring will only be strong enough for standard amount of amps and so melt wires before heating fuse and casing melting it

I do think the wiring is slightly too small for what I'm using it for.. the original blade fuse had some heat issues so I avoided the issue by changing to an inline fuse of the same amperage rating (25A). I see this probably wasn't ideal.. what sort of gauge wire should I have run to these things? at the moment it's 10A rated normal wire I think... whatever was run to the V6 thermo fan is what I'm still using.

suggest using a relay to power fans straight from battery and use the fuse to switch the realy so they operate like normal

It's on a relay, set up same way as factory V6 thermo was.. (I joined the 4 wires off the AU fans to the 2 pins on the original VN fan plug), only difference is my inline fuse.

hope this helps...

Sure does thanks, I've currently (current..lol) no bloody idea with electrics but I'm slowly learning.

 

[wamboin23]

i setup a set of AU twin thermos the other day, were blowing 40amp fuses because of the startup current draw. needed either a bigger fuse, or an auto reset circuit breaker.

once running, they only draw around 10amps per fan.

 

[db_notso]

go buy a ten dollar multimeter from jay car for one~! they are cheap and effective

there could be a short UNDER the fuse box where the fuse was
if the wiring is had it it will look black and scored on its sheathing
you COULD trace it by eye and look for damage...
but this will not garantee if faulty

is the 25 amp fuse was the same it SHOULD be okay
if you fit another fuse and it blows straight away you definately have a short in the circuit

a melted wire WOULD explain the multiple circuits that have died
PERSONALLY i would use multimeter to check it out accurately BUT a visual inspection could be done but remember its all the way from the fuse (power source)
all the way to the earth (for fans on vn? follow the wires or where you connected the earth wiring too)

 

[delcowizzid]

put a seperate fuse to each fan after the relay as said above startup current on 2 fans is huge 40 odd amps and if you want fused power to before the relay use an amp fuse holder

 

[savage1987]

delco, how do I do that - bridge where I have the fuse now and just direct power to relay???? then 1 fuse per fan? or what.. I don't really get it

 

[db_notso]

i think hes saying run two fuses and tow sets of wiring to the fans after the relay?
which would work by splitting the amperage to the fans by using two paths too the fans more volts and less current

but if the fuse is melting before the relay?

thats why i thought of using the existing relay to run another relay with its own larger wiring and its own fuse at battery and power fans from that
using old relay to switch new bigger relay thereby still only needing one circuit