In hooking up the wide band, we ended up inadvertently going on the hunt for a keyed 12 volt source. Initially, I just wired it in to the oil pressure switch (dummy light). I noticed after a while the gauge would still not read, but instead it would pulsate. Whenever it pulsated, the oil pressure dummy light would also faintly pulsate as well. I swapped to the temp sender (also dummy light) and it was doing the same thing.

Pops took the wire and jammed it in the alternator just to see if it'd work, and sure enough it did. Obviously we both knew that'd be a temporary thing, and once I parked the car it was unhooked and I went ahead and disconnected the battery for good measure..but where would be a good place to tap into for the keyed 12 volt source?

 

There should be a spade marked IGN on your fuse block. If I remember correctly, it's hot when the key is turned to the on position.

 

Good call, I didn't even think about running it there. 🤦‍♂️

(yes, this is an old picture..fuses have been replaced since then)

 

Okay, bonus question. Where is an easily accessible place under the dash (yes, that sounds like an oxymoron) to hook the ground to?

im gonna try to get up under there and tidy this up over the weekend, then also swap carbs to get a reading with the wideband for that one (just to determine if my suspicions are correct about that one)

 

If you Olds has the courtesy light option, they are black and orange, black is a good ground, you may try that.

 

Well, I stuck my head under there as best I could without getting on the floor/laying upside down/etc and found what appears to be another ground which has been added in.


..just now I've gotta get under there and figure out what that is. I also need to reconnect the duct apparently too. I love lists.

 

There you go, that will work too. Just an FYI the hole with the two slots is where the under dash light would go if you had that option on your car.
The harness end may be under there somewhere though, good luck.

 

I thought that had to do with the map light on the mirror..but then again it kinda looks like the harness thats zip tied up and after replacing the mirror (separate issue) the light doesn't work. I'd just not back under it to sort that yet.

 

That should be a decent ground, but that connector looks kinda sketchy so make your own for the wideband system. You should have a piece of plastic ducting that goes under the dash to connect to that cloth duct. There will certainly not be any ducting above the steering column for it.

Your map lights and under-dash lights are probably on the same fuse circuit. Since you have a missing under-dash duct, that is probably why you don't have that under-dash light. It would cover it up. There may be a light in the missing ducting.