[O'Man]

1972 Chevelle. Factory Automatic Floor shift

On the top of the steering column there is a switch of some sort that is bolted to the column. It is a semi circular switch with 3 separate "sets' / "pairs" of connectors The switch is activated by some mechanism inside the column which is controlled by the shifter position.

The switch apparently efffects 3 separate items in the car. I believe that the switch operation (or at least some part of the operation of the switch) is for (#1) the Neutral Safety Switching function. It also appears that the switch has a function related to (#2) Backup lights and apparently a function (#3) related to the seat belts(?)

At any rate my question is related to two of the wires that go to the farthest right hand terminal "set" on the switch. I am assuming that you are viewing the switch as installed on top of the column and that you are viewing the column as if you were seated in the drivers seat. The wire sizes are I believe 12 PPL (#12 Purple) and 12 PPL / DBL / W (# 12 Purple with double white stripe).

Can anyone tell me what each of those wires is for? I think that the portion of the switch they attach to prevents starting unless the trans is in Neutral or Park but the wires are not connected to anything at this point. I don't know which one goes to which terminal on the far right side of the switch. I should add they are separate wires at this point in time ..they do not have what I think should be a two wire GM 'connector" that orients the correct wire to the correct terminal on the switch. One wire has the original plastic GM connector still on it..that remaining connector has clearly been separated from another plastic conntector that I ASSUME housed the other PPl wire. The other wire has an aftermarket blade connector added to its end point

Just to summarize

#1 What is the function of each of those wires?

#2 What terminal on the switch does each wire go to?

Thanks for you help on this.

 

[Tom Mobley]

TTT, good questions.

 

[Tom Mobley]

I think the #12 ppl goes to the starter. I can't imagine why either of those other two functions would need heavy wire like that.

 

[O'Man]

I think the #12 ppl goes to the starter. I can't imagine why either of those other two functions would need heavy wire like that.

Tom

12 isn't really that big..not relatively speaking. I though some more about it last night after writing the post. I think that the function might be as follows.

When the trans is in other than park or neutral the starter wont engage. The mechanical position of that switch is controlled by rotation of parts of the steering column. The rotation of those parts is controlled by that lever that comes up from the trans to the steering column.

I am now thinking that one of those wires is a 12 supply that goes to the switch. With the switch is close there is juice to allow the car to start (when the car is in park or neutral). When the switch is "open" no juice to the starter..no start1

Now the question is which one has the juice and which one goes to the starter. I think I might be able to figure that out with a multimeter. I still need to understand which wire goes on which terminal.

Does this logic make sense to you or have I missed something?

 

[Dean]

Right, one purple comes from the ignition and is only hot during switch in start position and the other purple goes to the "S" terminal on the starter solenoid. Can't remember which is which but I think the purple/white is from the ignition. Anyway it's pretty easy to tell with a test light or meter.

It doesn't really matter which wire is on which terminal on a spst switch.

 

[1Fast7D]

Can't remember which is which but I think the purple/white is from the ignition.

Correct

 

[O'Man]

Right, one purple comes from the ignition and is only hot during switch in start position and the other purple goes to the "S" terminal on the starter solenoid. Can't remember which is which but I think the purple/white is from the ignition. Anyway it's pretty easy to tell with a test light or meter.

It doesn't really matter which wire is on which terminal on a spst switch.

Now before I bore you with reading thru the entire post here is a remaining question. On the other end of the switch assy...the end furthest from the purple wires there is another pair of wires. What do those two do? I need to go and relocate my wiring diagram but I think that possibly that pair has something to do with the seat belt warning buzzer??? Last but not least I believe that the middle pair is for the backup light circuit?

Now on to what I learned from you guys and from messing around with my trusty FLUKE Multi Meter...................

I started looking under there and discovered the following. I have to say going in that I was not under the impression that there were 3 electrically separate switches inside that plastic and metal case. I thought there was / were some sort of interconnection(s) between the blade connector pairs back there. Now I am not so sure but I kinda doubt my previous interconnection between pairs theory.

After poking around with the multi meter / continuity tester I believe that there are three distinctly different and electrically separate switches encased in the ONE plastic case that attaches to the top side of the column. Looking at the switch from the terminal / blade side there are three (3) separate pairs of terminals for a total of 6 connection points. Am I correct on this three separate switch theory? If I am right things get MUCH simpler to figure out

Each of the 3 separate blade pairs has continuity between their respective two blade connectors only when the little column actuated tab is positioned UNDER that portion of the switch. Move the column actuated tab away from one of the terminal connecetion pairs and there is no connection between the poles of that particular pair. At that point there could be no current flow across the two poles of any of the switches.

Agreed that it matters not a whit on a spst switch which side of the blade pair is the power supply wire and and which side is the output ..AKA supplIED power... to a given load device. All my confusion was generated because I thought that there was / were inteconnection(s) inside the switch between the blade connector pairs.

Agreed about the two purple wires and what they do. One has two white stripes as I said last night. Agreed on the single pole single throw switch as mentioned up above.