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Discussion Starter · #1 ·
2005 D22 Navara. Running well until last week.
Now has a severe electrical problem.
When the ignition is turned ON the following fuses blow:
  • Wipers
  • Turn
  • LEFT headlight
  • Tail lights

Everything else is fine (eg Right headlight, brake lights, radio, fan dash lights etc)
So we know it's a short somewhere (doh) but where?

We have the schematics and the items identfied above are not on any common rail/circuit. Other items that are on the same rail (eg coming from the Ignition relay) dont blow a fuse. So there seems to be nothing obvious in common.
I have fixed numerous shorts on vehicles over the years (the joys of working with old cars) but they either
a) are a short in the wiring to one device (eg horn) in which case they blow the fuse to that device OR
b) they are a short between the battery and the fuse box (ie main power feed before it gets distrubuted) in which case the blow the 80A fuse or fusible link

How can a short work such that it blows 4 separate individual devices fuses but NOT any fusible links or primary feeds?
Any ideas? This is doing my head in.

Hope someone has seen something like this before.
Thanks
 

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Discussion Starter · #3 ·
My first thought is the stop/tail light bulb, very occasionally the filaments short.
Thanks for the reply but whilst a short in the tail light would blow the tail light fuse - how would it also blow wiper+left headlight+turn ?
Its the multiple fuses blowing that has me stumped.
When you get a short current takes the shortest path to earth - so how could that be through 4 different unconnected circuits?
 

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I would do a parasitic draw plan...take all fuses from all "fuse blowing units" put your ignition on, put a good fuse in item "A", say Wipers,.....everything ok...? next item....do each test singularly then in pairs....then....you get the idea.....
 

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Discussion Starter · #6 ·
So I have pulled all 4 fuses that are blowing.
Ignition on - everything that is not blown works ok.
Replace any of the 4 that blow individually and turn ignition and device (eg wipers) on that fuse blows.

My mental model of how circuits work is:

battery -1> fuse -2> load -3> switch -4> ground

for fuse to too much current must flow through it. Which means it must be shorted AFTER point 2.
But how could that happen for 4 separate circuits?

I'll do some more testing today
 

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So I have pulled all 4 fuses that are blowing.
Ignition on - everything that is not blown works ok.
Replace any of the 4 that blow individually and turn ignition and device (eg wipers) on that fuse blows.

My mental model of how circuits work is:

battery -1> fuse -2> load -3> switch -4> ground

for fuse to too much current must flow through it. Which means it must be shorted AFTER point 2.
But how could that happen for 4 separate circuits?

I'll do some more testing today
The circuits are normally

1 fuse
2 switch
3 load
4 ground.

You had 2 and 3 the wrong way round for most circuits.


So the fault would logically be between 1 and 2.

You haven't got towing electrics fitted have you?
 

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Discussion Starter · #9 ·
Update:

Tried to narrow down problems using Headlight circuit, because Left headlight is faulty and Right headlight is fine.

Disconnect plugs from Headlight switch on console:
  • Red-Green (10) => Left hand Globe centre pin
  • Red-Black(5) => Right hand globe centre pin

REMOVE globes and test continuity to earth (there shouldnt be any):
  • R/G (Left) -> 0.0 Ohms (short-circuit) – this is fault with globe out
  • R/B (Right) -> Infinity (ie no continuity - this is correct with globe out – there should be no path to earth)

From Switch on steering column, loom routes to M5/E101 connector in drivers footwell.
Disconnect M5/E101 – thereby disconnecting loom within cabin.
  • R/G (Left) -> ) 0.0 Ohms (short) - fault
  • R/B (Right) -> Infinity (ie no continuity - this is correct with globe out – there should be no path to earth)

So fault is within loom between M5 plug and Left globe connector according to my logic?
Visual check of loom (though RH wheel arch) identifies no obvious cuts or abrasions to loom.

I have a week before I can get back to it. Any thoughts on the above?
 

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Discussion Starter · #11 ·
The circuits are normally

1 fuse
2 switch
3 load
4 ground.

You had 2 and 3 the wrong way round for most circuits.


So the fault would logically be between 1 and 2.

You haven't got towing electrics fitted have you?
Yep - oops
switch before load - at least for headlight circuit anyway.

But fault must be between 2 & 3 (between switch and load)
If it was before switch then fuse would blow regardless of switch - it doesnt - It blows when switch is turned on.
If it was after load it wouldnt matter - because its grounded any way.
If it was before fuse, then fuse wouldnt blow.

Thats my logic - hoping I'm right :)
 
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