I have a 1970 convertible, 350 w/ manual 4 speed.
I suspect the CSS (clutch safety switch) is intermittently failing/having issues. I want to confirm it is the CSS before replacing it so I know the problem is actually fixed.
I tried to add a toggle switch into the circuit, but doesn't seem to be working. What I did.....
There is a spade connector that connect the 2 wires from the CSS to 2 purple wires. I pulled the connector apart and tried to inserted a toggle switch; the way I did it is difficult to explain, but here it goes.
I 've attached some pictures for reference, but basically I think that one purple wire connects with one of the CSS wires, continues to the CSS, when the clutch is out, it creates a break in the circuit, not allowing the car to start, when the clutch is pushed in, it completes the circuit and the car will try to start. That circuit still exists, but there is a toggle switch connecting that has a connection between the wire going into the CSS and the wire coming out of the CSS. The thought is....run the car as normal, but if/when it won't start (acts like the CSS circuit isn't closed), I can use the toggle switch to bypass the CSS, and if the car tries to start, I know the CSS is the problem. Unfortunately, it seems the way I set it up has no effect because I push the clutch in, and car tries to start, leave the clutch out and it won't (which is how it is suppose to be), If I leave the clutch out and use the toggle switch, I think it should bypass the CSS and should try to start, but it doesn't. The car behaves like the I never put in a toggle switch. If the clutch is not pushed in, regardless of if the toggle switch is on or off, the car will not try and start.
What an I doing wrong???

 

the toggle switch I'm using is a Heavy-Duty Rocker Switch SPST. On the back, it reads: 10 A 277 V AC, 20V AC / 3/4 HP 125-250 V AC

Should this switch work?

 

Have you tested the switch with an ohmmeter to confirm it works?

 

Here are some wiring diagrams. Note that 1970 gets two, early and late.

http://wordpress.keystonestatecorvet...m/?page_id=118

I'm not sure I've ever driven a used car that had a working clutch safety switch. My C3 certainly doesn't have one. I thought bypassing it was as simple as tying the two purple wires together, but I never had to do it.

 

Yup, bypassing it is as simple as connecting the two wires together. The clutch switch just completes the circuit. Not certain where the OP has gone wrong as well. But I'd be checking that add on rocker switch as well.

 

Thanks all,
I was using a 120V AC toggle switch and changed it to a DC 12V, also found one of the connections was loose. Now it works the way I expected it to.
yeah, I could have just jumped thr 2 purple wires, but it’s technically my wife’s car, and she wanted to have the clutch switch in it and working. I also want to make sure it is the reason it would start sometimes (exact same symptoms as the clutch safety switch not completing the circuit, so 90% sure.
I figure when it won’t start, she can flip the toggle and we will know for sure if that is indeed the culprit!
Thanks for everyone jumping in to help!
Merry Christmas all.

 

Consider changing out the toggle to a momentary, normally open switch where you have to hold it to make the connection. Eventually the toggle will be left ON and the car will be started in gear. Result - front, or rear, bumper damage!

 

I don't know. You get so used to stepping on the clutch to start that I find I always step the clutch to the floor on my modern car to start it. And it doesn't have a clutch safety switch, only one at the top of the clutch for cruise control.
So, yes my modern, (Japanese) automobile will start in gear without stepping on the clutch.
But force of habit, I always floor the clutch when starting.

 

While I agree with 4-vettes that it gets to be habitual and a good habit of a long-time manual driver to press that clutch. However, there are some other factors to consider:
Assume the toggle gets left in the ON position and somewhat forgotten about over a period of months or years.
1. He said his wife will be the primary driver. Her experience with a manual is unknown. She may forget to push the clutch when she tries to start it.
2. He may have outside mechanic work done on the car. If the car is being worked on by a local mechanic, they may get distracted and forget it is a manual, and reach their hand in the window to test crank the car while in gear. I know my carbureted car, when warmed, will crank surprisingly quick when I turn the key.
3. He may sell the car in the future to someone who may forget or not really understand the reason for the clutch safety switch.
4. The cost/trouble of swapping that toggle for a momentary type toggle is minimal compared to the potential bumper damage to the car lunging forward or backward when that key is twisted.
The only thing different for the driver is he would need to hold the toggle switch up while turning the key, similar to keeping the clutch depressed.

 

I don't have a dog in this fight, I've never had to bypass a clutch safety switch, and the OP is debugging so he doesn't replace the wrong part, but I can think of just as many reasons to leave it bypassed.

The most obvious:
Never trust or rely on a mechanical safety device. Always depress the clutch when starting the car. And only after checking that the car is in neutral by wiggling the stick a half-dozen times.

Also, you can move the car with the starter if you need to:
Pull it into the shop
Move out of the way
Get off of train tracks when stalled