Alternator question, battery is discharging quickly.

[TitaniumTT]

Ah. Ok, so heres what you need to do.....

Buy Scotch
Buy plane ticket
??????
Profit

Butt seriously, depending on how much of the harness you cut back or removes, and I think I know which harness you pulled out ... Giggitty ... you need to go back to the FE-03 connector, between the "Front" & "Engine" harness and find the B/W & W/B wires and run them up to the alternator and plug them in. That will do it.

If the FE-03 connector isn't around anymore, you can get them on the FEM-01 plug and route them up to the Alternator. That plug is or course located around the stock ECU.

Now, if you've already got a nice Ludwig Harness and you don't have the provisions in that harness for the Alternator, what you can do is use the vacant CAS wiring that you showed the pic of. Those will be in the Front Harness and routed over to where the ECU lives. From there it's a matter of jumping the wires from the FEW-01 plug to the CAS wires (R,W,L,G) and then making the connection to the Alt.

Any of those approaches will properly control the Alt and prevent battery drain. But the key is, regardless of what the internet says, or the GM crowd, the alt NEEDS both wires to work properly and not kill the battery either by slow discharging death, or 16V overcharging death