24 replies to this topic

[Clayman]

I took my fuse box out to clean it, then hooked it back up with the wires in the "correct" places ( i noted them down before i disconnected them). Everything worked fine then, the indicators to! (yay!). Then i try the lights and smoke starts coming out of the bonnet... even when i turned off the ignition completly the lights where still on. By the time i got the battery disconnected all the wires where completely melted... i mean what the hell? how does this happen.. jesus.

[Big_Adam]

is this a problem or a rant. means theirs a bad short somewere. start probing with a multimeter thats what i'd do and bust out a wiring diagram to find the problem.

[Clayman]

is this a problem or a rant. means theirs a bad short somewere. start probing with a multimeter thats what i'd do and bust out a wiring diagram to find the problem.

Nah its a problems, i dont see how the fuses didnt blow yet all the wires around them melted. I think its a problem with the spotlights.. i hate them thinsg anyway, there going. Tomorrow i'll see how burnt the wire in the loom is.. and hopefully it hasnt messed with any other wires.

[flameredturbo]

my bro put my batt in mine the wrong way round once and it did that so maybe you did get one of the wires the wrong way round.

[Big_Adam]

<<<snip>>>>
Nah its a problems, i dont see how the fuses didnt blow yet all the wires around them melted.

oh good point. sorry. not too good with electricals. have to wait for some smarter to pop along.

[pikey7]

It just takes one wire to be on wrong and the whole thing can go mental! And not even necessarily touch the fuses as that one wire may short things one side of the box, which than melts and shorts others. Its a vicious circle.

When you put things back together, make sure the wires you use haven't been damaged beyond repair. If so, replace any sections by soldering them, and use "sealing" heatshrink. Then not only replace them where you noted, but also treble check them with the haynes manual. If you can, use the same coloured wires as original too, but that's usually a bit excessive when you're replacing 12 colours!

[Wiggy]

If so, replace any sections by soldering them, and use "sealing" heatshrink.

Also known as 'Adhesive Lined Heatshrink' FYI. Oh, and heat it up a little bit even after it's shrunk. To melt the glue.


Hmm, how sad at 1:05am. Heh.

[taffy1967]

Well I once stupidly put my battery back in my Mini the wrong way around and then after attempting to attach the earth lead (I think, or it may have been the positive lead?), all I got was a load of sparks when the metal touched briefly. Well I didn't completely attach it thankfully.

But yes I don't think that caused my wiring to melt, well everything seemed okay and still worked fine afterwards at least?

[minidaves]

headlamps arnt fused in some minis, so i guess you have a short on the light system

dave

[dklawson]

I didn't post yesterday as I presumed your car to be much later than mine with presumably a very different wiring schematic.

Minidaves confirmed what I was going to post... that headlights are unfused. On early cars they were also un-switched... meaning they could be on with the ignition key out of the car. If somehow you connected the headlight wires incorrectly they could short. Without a fuse the headlight wires will melt inside the harness taking everything with them. From memory, the old Lucas color codes were a blue wire to the dimmer switch with blue/red and blue/white wires going to the headlamps. If you connected either the blue/red or blue/white to ground by accident you could easily create the situation you're describing.

[Clayman]

I didn't post yesterday as I presumed your car to be much later than mine with presumably a very different wiring schematic.

Minidaves confirmed what I was going to post... that headlights are unfused. On early cars they were also un-switched... meaning they could be on with the ignition key out of the car. If somehow you connected the headlight wires incorrectly they could short. Without a fuse the headlight wires will melt inside the harness taking everything with them. From memory, the old Lucas color codes were a blue wire to the dimmer switch with blue/red and blue/white wires going to the headlamps. If you connected either the blue/red or blue/white to ground by accident you could easily create the situation you're describing.

It was 2 brown wires that got it, both on the same fuse. Could one of these be the lights? Or even the spotlights that someone has added at some point.

I got help awhile ago when i had troubles after replacing the old fuse box. There was originally one brown wire on the top fuse, and one below it on the 3rd connector. The 2 brown wires where then put on the same fuse as the haynes said that connector had a brown wire.. on the 3rd connector. Before i cleaned it, nothing happened.. I dunno..

[dklawson]

Again, my car and it's wiring schematic are probably a lot older than yours. In the old Lucas color codes, the brown wires were un-fused connections between the starter solenoid and fuse box, and between the solenoid and alternator. Another brown wire connected at the fuse box and went TO the lighting switch. The two wires JOINED at the fuse box but they were not fused... they didn't pass through the fuse.

Without seeing the carnage, it sounds like you've developed a serious short on the brown wire leaving the fuse box going to the lighting switch. Others will have to tell you places to look for this short but I'd suggest starting by replacing those two brown wires and looking for shorts on parallel wires using a volt/ohm meter. If the brown wires were bundled tightly with others in the loom there's a good chance that the wires running parallel to the brown ones were damaged and will need attention.

[Clayman]

[quote name='dklawson' date='Jun 14 2006, 05:45 PM' post='306533']
Again, my car and it's wiring schematic are probably a lot older than yours. In the old Lucas color codes, the brown wires were un-fused connections between the starter solenoid and fuse box, and between the solenoid and alternator. Another brown wire connected at the fuse box and went TO the lighting switch. The two wires JOINED at the fuse box but they were not fused... they didn't pass through the fuse.

Why are they connected to the fuse box? Ahhh whats going on

Whats this shrink heat stuff?

[dklawson]

You REALLY need a schematic for your particular car. I don't want to lead you astray by talking about stuff that doesn't apply to your particular car.

Why do the brown wires join but not pass through the fuse box? Power comes from the battery to the starter solenoid through the big cable under the car body. At the solenoid, a heavy gauge brown wire carries the power for the car's electrical system TO the fuse box. That fuse box connection is used as a junction. The second brown wire leaves that junction point and goes to the headlight switch. As mentioned, the headlight circuit is unfused and doesn't pass through the ignition switch nor does it pass through the fuse box. This allows you to leave the headlamps on with the engine off and the ignition key out. Why BMC/BL/Rover failed to put inline fuses on the headlights is a mystery to me.

Somebody with a later car needs to comment on any errors I've made above as I don't have wiring diagrams that cover cars with alternators.

[minidaves]

brown wires are a perm feed to you fuse box, and if they have melted then proberly your fuse box is shorting out on the bulkhead

dave