Understanding 12 volt wiring. The basics!

Rusty Panels

Well-Known Member
@Rusty Panels , the wiring in my old Disco is a dogs breakfast after years of dodgy work done by multiple people, sadly including me, feel like dropping over for a BBQ and a afternoon or two of fixing, I just couldn’t be bothered after spending all week installing cabling and equipment
Love to help you out Matt but the tyranny of distance and all the restrictions make that a bit difficult. You just need to get motivated and get those wire cutters snip, snip snipping! Disconnect the earth wire fist though ! ;)
 

Rusty Panels

Well-Known Member
After all that I said today I must report that I blew it! I literally blew my alternator, or at least I cooked it!
I had a new clutch put in a few weeks ago and had the rear main oil seal replaced at the same time. The rear main was leaking as the mechanic said (yes I went to a mechanic!) (4wd boxes have always frightened me due to their size and I don't have one of those big gearbox jack things). Apparently the rear main had been replaced and was not sitting square so therefore the leak. If there's one thing I hate it's oil leaks. Despite the rear main being replaced the oil spots on the garage floor persisted. As there was quite a bit of old oil still laying in the nooks and crannies I decided yesterday to give the old girl a good dose of degreaser followed by a good hose down. That all went well and I was convinced that I had probably solved the oil spots on the garage floor problem.
Took the cruiser for a run into town this morning and being that it was a very warm day had the aircon running and the windows up. I also had the music pumping through the recently installed Pioneer and sub woofer so, I was in a happy place.
I had travelled about 10 k's in my happy state when all of a sudden the music stopped I glanced at the dash and found that not only had AC/DC ceased to belt out of my speakers but the speedo, tacho, fuel, oil, temperature and every other gauge and function had also stopped. The engine was still running thank goodness.
The only circuit that worked was the headlights (no tail lights, indicators or brake lights). I turned around and went home hoping that the cops wouldn't spot me.
After a bit of checking and a lot of thinking I checked the black box that is mounted on the positive terminal on the starting battery. It is a square plastic box about 75 x 75mm. I ended up pulling it apart and found that it is in fact nothing more than a big fuse that feeds 4 connectors and also has a terminal that comes from the alternator. It had a fused section on it that fed 3 of the 4 connectors. After a bit of checking with the trusty multimeter I came to the conclusion that the wire that came from the alternator may be the problem.
When I managed to get a better visual on the alternator I could clearly see that there was a quantity of burnt material on the windings.
Obviously there was a problem with the insulation on the windings. I don't think that I sprayed an excessive amount of water in that area. In any case an alternator should be able to handle complete submergence without becoming a molten blob.
Anyway, the new one has been ordered so here we go again.
 
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