MGB 77 MGB Alternator Wiring

[kyreb1862]

The other day I made a post about my alternator not behaving as I thought it should. I decided to pull the alternator and have it checked. The alternator shop informed me that they couldn't find anything wrong with the alternator and in the process of removing the alternator I may have discovered the answer to my problem. I only have (2) wires connected to my alternator and both of them are brown. The yellow/brown wire is missing. So far I haven't been able to locate it in the wiring harness. Is there any chance that the factory could have used another color? The only unused wire I have found so far seems to be black. If any of you have a good picture of the wiring at the back of your 16acr alternator please post it so I can see where the yellow/brown wire is supposed to be in the harness.

Regards John

 

[DJThom]

Your alternator will not work without the "yellow" wire on, which is you ignition warning light. If the alternator doesn't sense a load on that wire when you turn the key it will not work. Learned that the hard way when I used a LED in the ignition warning circuit which didn't draw enough current to switch the internal relay on.

See if you can follow that wire or find out what colour leaves the dash light

 

[kyreb1862]

Thanks for the help DJTHom. I went through the wiring yesterday and found a little DPO trick I would have never thought of. My DPO had cut the terminal off the yellow/brown wire and hooked it into the unused wire that led to the former seatbelt inter lock system. I cut this loose and wired it back into the alternator and now it works as it should.

Regards John

 

[jlaird]

That's almost one for the joke book.

 

[rick_ingram]

My DPO had cut the terminal off the yellow/brown wire and hooked it into the unused wire that led to the former seatbelt inter lock system.

WTF?!?!

Guess that's a front runner for the role of "the emitomy of a DPO"!