Chasing Gremlins

[mmt 15]

Hi Guys, 

Can you please help me with some basic pointers on How to find a short. 
 

I have a fuse which shorts. Meaning, when I put a fuse in the socket it shorts/blows. 
 

Non standard (Racing) fusebox and wiring. 
 

What is wrong and How do I find it? 
 

thanks. 

/M

[boldy205 75]

What items does the fuse protect?

[mmt 15]

Thanks. It protects the ECU and and and miscll. 
 

It use to work - it is something I’ve connected incorrectly I think. 
 

what should I look for? 

[Anthony 1,003]

Unplug the devices powered by that fuse - if the fuse still blows with nothing connected, you've likely got wiring shorted to ground, and if it doesn't, plug the devices back in one by one until it blows the fuse again and there's your culprit.

[mmt 15]

Thanks Anthony.
 

Wiring is not my strong side. I’ll be as methodical as possible. 

[Anthony 1,003]

The first challenge is normally identifying what's powered by a particular fuse - this can be enough of a headache on a standard production car, and more so on anything that's had a non-standard re-wire at some point.  Sounds like you've already got a pretty good idea, so you're already part way there  

 

If it does look like it's a wiring fault, I'd start by checking the loom near to where it runs close to or through any body metalwork or near to the engine/gearbox, as that's usually where you find wiring that's rubbed through and is shorting to ground.  Also, if the fault occurred around the same time as you were working on the car, check around the area where you've been working and double check any connections might have touched.

 

At least on the bright side you also have a constant, easily repeatable fault - much easier to diagnose and be confident that it's resolved than an intermittent one where the fault only occurs once in a blue moon.

[mmt 15]

First of all - thank you for the pointers AND the encurragement. 
 

Found the culprit(s): Rainlight and Transponder was connected incorrectly and caused the short. Blew 12 (twelwe!) fuses on my Way to salvation. 
 

everything is now working. 
 

got it started up and is now ready for next race day. 
 

thanks again. 

[SRDT 175]

You can buy circuit breakers to replace important fuses, this way you don't have to carry tens of spare fuses just in case.