What are these wires for?

[TommyGuns]

I have an 83 K10 Silverado. A previous owner or the mechanic they hired did a swap from the truck's original 305 to a crate 350. Unfortunately they did not bother to connect the wiring to the A/C, the transmission TCC wiring, and they completely threw out the cruise control assembly. I'm slowly working to restore this stuff, and the next thing I want to tackle is this cut bundle of wires on the passenger side of the firewall above the valve cover: https://imgur.com/a/C4l3f8c

The only wire they left connected from this bundle is what appears to be a ground wire, connected to the back of the engine.

The other wires are:

• A very Light Pink
• Light Green
• White
• Two? Dark Brown wires
• Yellow

As of now, the only things not working in my truck are the A/C compressor, the TCC lockup, and the Cruise Control. The AC blower motor works, as does the vacuum driven A/C vent doors in the cab. Looking at the wiring diagrams are not all that helpful in this case, as they don't specify where on the firewall the "grommet" in each diagram is located. Also several RPO option diagrams share some wire colors passing through the firewall. I hope the location of the grommet will help identify what these wires go to.

Does anyone have any idea what these are for?

[TommyGuns]

Here is a better shot of the wires in another truck. I’m not sure if the Weatherpack connector is stock, but the location and wire colors appear to match.

The unknown wires are circled in green.

[THI]

Over your glovebox in the dash is a control box that was used for the Electronic Spark Control (knock sensor). If your distributor has been changed there would be no need for those wires.

[Loco83]

How does she run with the 350?

[TommyGuns]

Originally Posted by THI

Over your glovebox in the dash is a control box that was used for the Electronic Spark Control (knock sensor). If your distributor has been changed there would be no need for those wires.

Wow, I didn't even figure there would be a module like that on a non-ECU truck. Sure enough there it is right above the glovebox with the exact bundle of wires I see in the engine bay.

What I'm really looking for is the wiring necessary to hook up the TCC, and I hoped it would be in that bundle. The RPO code for the transmission is MX0, there is no other code, which leads me to conclude that this truck has always had a 700R4... and that is what it has now. Right now the TCC never locks up, and there is no wire going to the three pin connector on the driver side of the transmission

[TommyGuns]

Originally Posted by Loco83

How does she run with the 350?

Runs pretty good! A data plate on the side of the block tells me it is a GM Performance 350 HO, PN 19433030:
https://www.summitracing.com/parts/nal-19433030

I had a hell of a time with this truck when I first purchased it. Vapor lock was a menace with the truck having a true dual exhaust and long tube headers running right next to the fuel lines on the passenger frame rail.... plus a mechanical fuel pump adding more heat to the gas. Not to mention gasoline under suction will have an even lower vapor point than normal, making the problem worse. After trying a variety of things, I finally decided to put a Pro Flo 4 system on it, swapped the tanks for 87 TBI tanks, installed a new hard line to supply the engine and sleeved it in insulation. So far it runs great, and the motor comes stock with a mild cam as well.

[Loco83]

[Willie Makeit]

The TCC lockup is controled by a vacuum switch on the firewall. Most are mounted above and to the left of the brake booster.