Brake Light Fuse blowing

[Mr Polson 10,214]

Brake light fuse in my XF ute keeps blowing every time I turn the ignition on.

 

Its not the brake switch (eliminated by unplugging it and turning key).

 

I've checked the wiring at the lights and towbar, all seems fine. Pulled the access panels off in the tray and checked the wires, all good there.

 

Where do I check next?

 

Not sure if it matters, but it has a Ghia/ZL dash.

[bear351c 10,273]

It's probly an earth leak. The loom sits on metal, all its life, and slowly vibrates until one strand of copper touches, and bingo!

 

Chased similar prob in my FC LTD, turned out to be where the loom goes over rear wheel arch under back seat. Couldnt see it, but, after I rewound the cables with ins tape, problem went away.

[Crazy2287 1,886]

Not familiar with the circuit. It sounds like you will need to spend a bit of time with a multimeter.

[Mr Polson 10,214]

I've checked the loom from the wheel arches back and it's all fine, I think. It still has all the clips that hold the actual wiring up off the metal too.

 

Thinking of pulling it out and putting it in that black stuff (forget its name, it's like a corrugated tube).

 

How can I trace it with a multimeter if the fuse blows as soon as I turn the ignition on?

[Crazy2287 1,886]

Pull the light globes out.

test resistance of each wire length, should be less than 10 ohm

check resistance BETWEEN each wire, should be infinite.

Check resistance to ground, Should be infinite except earth wires.

If the fuse is ALWAYS blowing STRAIGHT away you should be able to track it down as the fault is constant.

[Mr Polson 10,214]

Stupid wiring is stupid. Have traced it to being in dash loom or engine bay loom.

 

Pulled dash out. Will dismantle whole loom and investigate..