Help with wire identification.

[Cmillet]

All 3 of these wires are on the passenger side. The green wire and the black wire comes out of the same little cluster. The black one has a plug still on the end. The yellow wire comes out of the same little cluster as the starter wire. It also looks like a wire may have broke off of the starter. (Truck still starts fine)
Also their is some kind of sending unit in the block without a wire. Thanks for your help.

[kwmech]

Early attempt at emissions control. Time to eliminate some wires

[Cmillet]

All 3 were for emissions???

['68OrangeSunshine]

If the PO converted to HEI, the 20 Yellow line to the [Points] Coil Positive terminal would be redundant. It forks also to the Starter, also no longer necessary.
Tape it off good, in case the other side is still connected to power, so it doesn't short out.

[Cmillet]

Anyone else know what these wires are for??? Esp the black plug.

[leftybass209]

http://67-72chevytrucks.com/vboard/s...d.php?t=470268

This is the schematic for these trucks. As far as the black wire.... the color doesn't matter where the plug end is at... it could have been spliced in. You should trace that wire to find where it enters the fuse block.

That location will tell you much more about what the wire is, or what someone may have spliced it to accomplish.

['68OrangeSunshine]

Originally Posted by Cmillet

Anyone else know what these wires are for??? Esp the black plug.

The plug looks like the one for the Reverse/Back-Up light switch that connects to the transmission. Is it long enough to reach back into the tunnel? Does the truck have a Manual Transmission? If it doesn't now, what does the SPID read? If it does have a manual, do the back up lights work?

Green wire is usually for Water Temp Sender.

The indicator probe under the pass/side manifold, above the starter is in the usual position for an electrical Oil Pressue Failure sender [''Idiot Light''] , although the device looks a lot like an electrical Water Temp Sender. ''Idiot Lights'' were so-called because, by the time they went off, the damage was already done. Water Temp sender was usually in the driv/side head, forward, or in the thermostat housing, front, top.

[Cmillet]

Thanks for the input. Here is what I know. It's not the reverse/back up wiring. Corrected that pretty blew a few weeks ago. It's not oil sending. That's on the block by the distributor and I have it working correctly. The drive train is 307 w turbo 350 auto tranny. (All original). None of these wires were added or spliced in. I know need to figure out the temp sending sensor and if it's working and location. When I ground the green wire, it makes this box click. (Or at least that's what I think is clicking)

Keep the clues coming!

[Cmillet]

Here is the pic.

[leftybass209]

What year truck is this?

[garyd1961]

Isn't that the gadget that delayed the timing or something like that when in 3rd gear? Never seen one hooked up.

[Cmillet]

It's a 1970.

[leftybass209]

It's very possible that it's remenince for the TCS, or Transmission controlled spark. You can go here....http://www.67-72chevytrucks.com/vboa....php?p=5781194

And download the 1970 chassis manual. Look at section 6T, or roughly page 385 on the pdf. It has a description and a diagram of what all the system contains.

['68OrangeSunshine]

Yeah, TCS. Terminal Controlled Spark. Totally unnecessary now. Delete it and the relay on the firewall.
Funny, on my '71 GMC w/350, the TCS relays were on the drivers' side.