Lights flicker all the time

[85crownHPP]

iirc that ground shouldn't be flowing juice for anything except the o2 sensor... Id take a good look at your other engine/frame/body grounds under the hood, clean them up and make sure they are tight.

[1980c10]

I dunno I had previously cleaned and tightened all other ground, and it didnt fix it. As soon as I hooked that up it was fixed.

[gadget73]

thats.... odd. I'm with Pete on that one, the O2 ground should only be for the O2 sensors, and maybe act as a voltage reference for the ECM. It should have no effect on the light circuits at all.

[85crownHPP]

It could be corrosion inside a ground cable that you cant see... if lights and other stuff are making ground through that O2 wire, its likely because their own grounds at some point are compromised.
Do you have an ohmmeter? If you probe the cables in various places like on the terminal, on whatever is fastening the terminal, IN the wire (pierce it) in various places, etc you can find any resistance you may have to the negative battery terminal.

[85crownHPP]

I forgot to ask... how big was this wire you fixed? the O2 sensor wire is pretty thin... if the one you fixed had any girth to it, then that was one of the main ground cables and may be the end of your troubles

[1980c10]

ummm, It was fairly small prolly 14-16 ga. I dunno I think im gonna replace the battery cables with some larger new stuff soon anyway. Even though its fixed the stock stuff seems in poor shape, and a bit small IMO. What do you all think. couldnt hurt right?

[Lincolnmania]

i would replace at least your ground cables

[1980c10]

Good lookin' out guys. I hate chasing electrical problems. Thanks for all the help everyone.

[1980c10]

It's back guys. You were right I was wrong, your smart i'm stupid, your pretty i'm ugly haha I kneel before you.

Anyway it came back about a week after I thought it was fixed. I have since re-cleaned all the grounds, and put a brand new main ground cable on. Still nothing and its worse this time than it was before. could it be to much resistance in the positive cable? Could my battery have a shorted out cell in it? Anyother Ideas? I'm at my wits end at this point.

[85crownHPP]

Have you looked at the headlight switch terminal and connector yet??
Also I'd look at the ignition switch /connector, both switches are known to short and/or fall apart on the inside causing strange things to happen.
Next time it happens, try wiggling the key and headlight switch and see if anything changes.

[1980c10]

Okay will do. The ground that goes from the engine to the firewall wall, were does it connect to the engine? or supposed to i should say.

[1980c10]

Got it God im a dumbass. It was the ground from firewall to engine. I must have missed it in my cleaning and checking grounds. But it was completly unhooked. I must not have hooked it back up when I did the H.O. swap. Thanks for putting up with me being a moron guys. I feel so stupid haha.