13Swords

I haven't got a wiring diagram and searching online AND thru Yotatech hasn't revealed the info I need.

Anyone with a 1978 pickup with the ORIGINAL Alternator Plug still on the harness; can I get a pic posted here or at least a description of the wire colors and their positions going into the back of the plug? Please?
Some dunderhead (yep, that would be ME ) cut the original plug off, without taking note of which wire went to which pin position. The plan was to put spade connectors on and just put them on the terminals separately, as I can't find a replacement pigtail anywhere out there.

The wire colors I have are white, blue and green. The wire that goes to the B+ terminal still has it's ring on it, so I know where that goes. It's mostly the green & blue wire I am concerned with. Those rotted away out of the plug, only leaving the white one, & I know where that goes, bottom left looking at the wire side of the plug.

Any help I can get would be greatly appreciated. Please let me know what you have. Thanks!!!

rowdy235

I'd check for ya if mine wasn't 50 miles away. If you have a wiring diagram maybe that can help?

91bluerunner

Hope this helps. It's from a Haynes manual. It's the only thing I can find seeing as I don't have a '78. It's also the only thing I can find that says white blue & green (w, b & g).
Good luck.

13Swords

No wiring diagram available. Of course I can find almost every other year trucks diagram online, just not the '78. Looks like someone else has chimed in with one, but I appreciate the response.

13Swords

Bluerunner, you are the BOMB; thanks so much for responding!

The pic you have there is for the older E-L-F connections, but I can do the conversion to the later F-E-N connection scheme. Don't know why they changed the labeling but it shouldn't be a problem. E = Earth (ground), F = Field (Rotor). N or L should be the sensing wire to the regulator. Pretty sure as your pic shows the regulator terminal to that marked as "L", which also happens to be the color code for Blue.
Who'd athunk it?

Thanks again for the help!!!

91bluerunner

I knew it wouldn't be exact, so I'm happy it helped!

13Swords

Of course after I needed it, I find an online source for the '78 wiring diagram:

http://www.globalsoftware-inc.com/co..._LC_Pickup.pdf

Should work for '77 too. Please note that 77 & 78 had electric fuel pumps in the tank.