What are these 3 wires in my engine harness?
 

I just want to make sure where these go...........

is that a aftermarket wiring harness? it looks nice. i think green is water temperature sender. red maybe your automatic choke? dont know, im just guessin about the red one, but pretty sure that originally the temp sender wire is green. good luck, Ben

Cory M has a diagram on his site that might help you...
http://www.geocities.com/chevroletc1070/wiringdias.html

The blue wire is for an oil pressure sending unit.
The Green wire's I believe are for AC compressor and Soleniod. Or for a temp sending unit near the thermostat housing ( Gm used green for both ac (light green) and temp sender wires(dark green)
The Pink hmmm nothing comes to mind right off hand. Possibly your old ignition coil + supply wire?

i THINK green is temp, blue no clue, and pink no clue, but i do know that there not on my 71s harness. BUT they were on a 70 harness i had

I did buy it new.it is one of those M&M harnesses, that GMC Paul's sells......My factory harness didn't have an oil pressure light, or it had been cut......I am running gauges.....as for the pink one....this one is really confusing me......if it is laid out right............this wire wants to go to the front of the motor somewhere.......I dunno...........lol.......thanks for the help though

get a voltameter, and figure out when it gets power, like with the key on, or put some volts to it and see if a guage moves? maybe that isnt a good idea. good luck tho, Ben

The blue or the red wire might be the electric choke wire.

The green wire may be for a tach.

If it is a stock harness I think the red one is for an anti-deseling solonoid that goes on the stock quadrajet.

I went with M&H also and had the same questions. This is way it goes. There are 2 green wires for temp sender. One plug works with warning light type sender the other works on gauge type. The pink/red goes to the solinoid on q-jet carb and the blue would go to oil pressure sender if you only had warning light and not gauge. I just cut off wires not needed and went with it.

BTW M&H uses only factory color/gauge and connectors in their replacement harness's, just the way it should be!