7 replies to this topic

[666junky]

Background info : 91 roundnose with an SPI rear loom for the fuel pump wiring joined up to a normal carb loom for the rest. This has been left mostly standard apart from adding an airhorn + its relay, and a rad fan + its relay. + a safety device and its relay.

 

The 4 cables coming from the ignition switch always used to get warm - to the degree the black connector block melted so a new one was added ( this was before i realised without solving the issue it will just return again!). So now it has : Switch - wires -bullet connectors - wires - black connector - rest of loom. 

 

Now, since the micra conversion we have added the micra loom to the above list - this is running through a single 10A blade fuse running off its own fuse box (im not sure if this is linked to the main fuse box in any way). - this in itself has been no trouble at all apart from blowing the fuse every the car hits the rev limiter - but for now i can deal with that. 

 

My issue is the white wire coming from the back of the ignition switch is now getting so hot it melted its covering and has started to melt the bullet connector and its clear rubber case. The 3 other cables also coming from the switch are also getting hot but im not sure if its just spreading from the white one. 

 

Help! I havnt had a chance to trace the white cable back yet but im going to replace the junk switch and cabling in favour of a new one but i know without solving the issue this cable may well melt too. Any ideas what it could be?

Ive read up about shorting and overloading - the wire doesnt take forever to warm up but it certainly isnt instant - i can keep my hand on it for about 2 mins before it burns! 

 

any ideas gang? Nelly is now my daily and im stuck without her!

[Ethel]

White is ignition live, just find some ignition dependent stuff you can offload to relays.

[666junky]

The thing is i think most of it already has a relay. The fan does, security device does, horn does. Is there anything obvious im missing? i didnt think there was much else that ran off that wiring? maybe the radio but that isnt even being used so i cant see how that is drawing a current? :/

[1984mini25]

The ignition live (white) is what practically drives all the electrics, with the switched ones coming from the ignition stich.

[666junky]

Im sorry but i dont really understand that, does that mean anything that can work whilst the engine is running goes through the white one? 

[1984mini25]

Anything that can work through the ignition switch, as the white wire is the main live (unfused) feed to it.

[Ethel]

The brown supplies  the ignition switch. The first key position (accessory) is for the heater, radio...anything that still works after you turn the engine off. White supplies the ignition coil directly and stuff like the wipers, indicators via the fuse box. White is unfused, ignition lives downstream of a fuse are green, unless they have specific component colours.

 

The horn and, I suspect, your security devices, won't have any connection to the ignition switch. If you mean the heater fan, that should be on the accessory position.

 

I suppose it's also possible you have a short somewhere. You could rig up a feed to the via a continuity/circuit tester. Unplug the ignition switch and hook up a small bulb or buzzer between the white and brown in its place - or better, an ammeter. Have everything switched off and unplug things until it indicates no current is flowing. The alternator should draw current, as will the engine's ignition, fuel pump and other bits that you know are unswitched, like the sensors for fuel, temp, oil...

 

It would still be a good idea to have the ignition feed for Micra loom via a relay. You could use the wire size as a rough indicator of how it matches the current carrying abilities of the Mini side, but beware if it's thin wall cable it'll have a higher capacity for the outer diameter.

 

 

...if it is a short, the wiper park switch is a likely suspect

[666junky]

Thank you, i took a look and my security device was plugged in allover the place, some in the 3rd down and others on the first and 2nd plugs.. removed all of it and so far no over heating problems at all. Going to look further into it and have a replacement loom on the way to put the micra loom through a relay too. :) cheers gang!!