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Electrical Help PLEASE!!

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19MGA60

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I don't know what I have!! Please click on the link below and look at the picture, double click on the picture and it will enlarge. I have numbered the items and I am not sure what the items are. Number 1 and 3 look the same and both have the same numbers on the top. Please let me know what the parts are by number. Are they all necessary? This is a 1977 MGB. In trying to start my car the main power wire to the fuse box started to melt. As you can tell I have a mess. Please help!!

https://f1.pg.photos.yahoo.com/ph/mga60t/album?.dir=/6dc0

Thanks, Tom
 
It sure is a mess. Can you start with what all works and then go backwards? # 4 looks like the signal light relay. #1 and 3 obviously plugged into to something else. You have to get a wiring diagram which must be available someplace. It will help tremendously.

I have no idea from the picture what the gray cable # 2 is or where it goes or came from. Or is #2 something else in the picture? Is anything working at all electrically?

Just checked what little I could find on Moss Motors site and that # 4 might be a battery cutoff relay.

https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29069
 
Relay 1 should be your Ignition Switch Relay.
I can't tell what #2 is refering to.
Relay 3 should be your Starter Solenoid Relay.
I have no solid Iidea on #4 but agree with Bruce that it looks like the picture of a battery cutoff relay?? whatever that is.

Of much more importance you need to find the ground (short) most likely one of the large brown wires going into your fuse panel (this assumes that the "Burning input wires" is refering to one of the brown wires. So;

1. Can you tell which brown wire it is? Or is it some other color?
2. Is it more than one?
3. How badly burned is it... does it look like there might be several wires fused together?

Answer these and we'll see where we can progress from ther.
Oh yeah, most important... do you have any maintenance manual for the car? If so, which one?

It may look nasty, but, it's not the end of the world Whatever Lucas built, we can fix.

Mike
 
My mistake. #1 and 3 looked like 5 pin plugs in the picture. Yes they do look like relays now that it was said. Is one of them possibly the flasher unit for turn signals. If turn signals do work, try unplugging one at time and see what happens. And it certainly could be the ignition switch relay as said above. Again, if ignition switch works (not trying to start car, but warning lights come on or whatever) try unplugging it and see if that stops the lights. Turn ignition off first, then unplug and then turn switch.
 
Adam,

The brown wires are hot at all times. However, while attempting to start the car (that is: turning the ignition on) a new path is generated (still on the upstream side of the fuses) which could cause the ground. It's important to realize that in order to generate enough current to melt the wire insulation there must be no fuse protection. This will typically put this type of problem somewhere in the Brown wire circuit,
There will be, at least two relays, and possibly three, together with the starter solenoid which can effect the circuitry at the brown wires. the two tabs they connect to on the fuse panel are just a junction point. try disconnecting them on your B and you will find that only one of them is hot the other one goes to the "ignition relay"

Mike
 
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