Unidentified Wires

[nuke82]

So I'm trying to finish up my wiring on my 72 Chevy and have a few left overs I can't figure out what they go to. I am also missing the electric choke wire and the Hydraulic brake pressure warning wire.

Choke: I have read on the forum the choke wire is a blue/green wire, however I do not have a blue wire coming from my firewall and the green wire is the engine temperature sensor wire. Was the factory wire daisy chained off another wire like the distributor power wire maybe? Does anyone have any pics of the wire I should be looking for? I know I could just wire something up but I'd rather do this factory style.

Brake pressure warning wire: For the brake pressure warning wire, I have the sensor, but no wire from the cab (pic below).

Unidentified wires: The two brown wires circled in the pics below are a mystery to me. One, brown with a white stripe, is only a foot long and there isn't anything that needs plugin into within a foot, the other, light brown, has an odd round plug. I thought this went to the brake pressure warning sensor but it's too short and the plugin is wrong.

Any help is appreciated and pictures are worth a thousand words!

[ray_mcavoy]

As far as I know, GM didn't start using electric chokes in their pickup trucks until into the mid to late 70's. So I doubt that your 72 harness will have a pre-existing choke wire ... you'll have to add one.

The light brown (tan) wire with the odd round plug (in your last pic) is the one for the brake pressure switch. However (from your first pic) it appears as though the proportioning valve on your truck has been moved to the 73+ location down on the front crossmember. They were originally mounted up near the master cylinder. And a newer prop valve could also explain why the plug doesn't match (they changed to a different style connector sometime in the late 70's).

[Bigdav160]

I agree with Ray. My first thought was someone did a crossmember swap and used the P-valve from the donor. I did that on a '67 and '63. But your's is a '72 so it should have had disc brakes and no need for the crossmember swap. Your P-valve should be under the master cylinder.

The wire-connector on the firewall is for the transmission spark control emission equipment. When I removed the TCS wiring/relay, I had the same connector left over.

[nuke82]

Thanks for the reply's guys!

For the choke I was assuming since I didn't have a manual choke it had to be electric, I never heard of a divorced choke before.

The truck has a Lincoln Versailles rear end, so I'm guessing whoever installed it must have redone the brake system as well when they converted it to 4 wheel disc brakes. Also the truck has 80's model motor mounts, the guy I bought it from said he did that to fit a big block in it. Could have done the front crossmember then too.