Please help identify wires

[dmjlambert]

I would like to ask you fine folks to please help me figure out a couple of wires. I am having trouble finding them on the wiring diagram. I am attaching pictures.

Picture 1:
Both of the wires have connectors.

Picture 2:
The pink wire comes out of the firewall using a grommet that looks like original factory wiring to me, a little bit above and to the right of the harness connector. But I suppose it could be an add-on for something.

Picture 3:
note 1 -- pink wire at the firewall
note 2 -- the connectors
note 3 -- the orange wire has a ragged end
note 4 -- they appear to be harnessed together at one point, now the wrapping is ragged

Picture 4:
Pink wire ends up at the fuse box, I am pointing to the pink wire with the red arrow.


The connector ends of both of these wires was sitting on top of the engine when I got the truck back from the mechanic who helped with engine installation. The mechanic gave me the helpful advise of don't worry about those wires, and hinted that the orange wire may have gone to the transmission to advance timing. The truck had a points distributor but has been upgraded to a used HEI and only one power wire goes to the distributor now. So, I don't know if these would have run to the old points distributor. I'm kind of thinking the pink wire may be power wire going to some accessory, and really don't know what to think of the orange wire. The heater blower motor has a purple wire going to it.

This is a 1969 Chevrolet CST/10 with 350 CU IN engine, Turbo 400 automatic transmission, factory air conditioning, no tachometer on the dash, and GM/Delco AM/FM/8-track.

[ray_mcavoy]

I believe those pink & orange wires were originally for the TH400 transmission kick down ... aka "passing gear".

As you have noticed, the pink wire receives power from the fuse panel and runs through a grommet in the firewall. From there, it ran to a kickdown switch mounted near the carburetor. Then the orange wire ran from the kickdown switch down to a connector on the transmission case that in turn connects to the kickdown solenoid inside the trans.

[dmjlambert]

That is interesting. I wonder if I should look into hooking that back up.

[TonyM]

I had exactly the same question as you. I'm fixing up a 67GMC and those wires are just hanging out. I was curious as to whether they should be hooked back up. What did you end up doing? Thanks!

[dmjlambert]

I obtained a carburetor mounted kick down switch like my truck had originally, and a new harness for it, and tested it, but have not yet actually hooked it up. I'm going to. In my test the TH400 does kick down into passing gear when the switch is pressed. I don't have driving habits that will make it active, perhaps ever, but I do like having it restored to original operation. If I liked passing people and driving like a maniac I would have made it a priority, but since I don't floor the gas pedal it is not going to get much action except perhaps just to test it. I am slowed down because also missing from my setup a proper throttle return spring and the tiny braket that is supposed to be screwed into the intake manifold to hold the spring in the right place under the switch. I'm moving the spring to the water neck instead. Here is an update of the mounting of the switch. https://67-72chevytrucks.com/vboard/...d.php?t=854591

[HO455]

Yes, you should hook it up. When properly adjusted the switch in conjunction with the vacuum modulator will allow your transmission to down shift properly on hills and when your heavily loaded. The switch contacts should make contact around 3/4 to 7/8 throttle.

When properly adjusted it will help prevent the engine from detonating under load.