The relay under the hood is only part of the system. It only comes into play if there is another problem, such as a faulty seat switch. Pushing on the button will allow you to start the car once...after that, you'd have to push it every time you wanted to start the car. You can remove the relay, but the system will still be active...you'd just be stuck, with no "over-ride" mechanism.

The Factory Service Manual has a whole chapter devoted to the diagnostics on the system, and a neat troubleshooting chart.

To by-pass/"disable" the clutch switch, simply tie the two wires together going to the switch connector..either with a jumper wire in the connector itself, or cut/splice the wires together.
It would be best to get the switch/rod back where it belongs, for safety reasons, but it's fine to by-pass it to find out where your no-start problem is.


This system is only installed on the '74 cars, and some very early '75s. In fact, all cars sold in the US in '74 were required by law to have it...the same system is in the Impala, Caprice, even Camaros. The other car manufacturers had their own versions of it, but they all had the seat-belt starter interlock system. Another brilliant idea from the minds of the safety nazis...Thanks RALPH...
The only good thing about this goofy system is, it's a dang good theft deterrent!

I just e-mailed you the wiring diagrams...they may help.
Adams' Apple2010-11-04 05:15:39

Ok. I figured out how to start it at the ignition switch, but first here's what I found. The interlock harness in the back behind driver's seat behind carpet. Two wires corroded off smaller connecter. black wire still attached. Unplugged the connecter. Next, under the steering wheel by the clutch switch area a small connecter with a thick wire looped (jumper wire?) looks like the clutch switch was bypassed?? '74Shark2010-11-05 12:13:08

Sounds like the switch on the lower column is out of adjustment or loose. By working it in ACC first it may be pulling the switch housing far enough back to allow the rod from the lock cylinder to move enough to close the start contacts.
The adjustment is easy, getting to it may be tough. Loosen the 2 mounting screws and with the key in the on position move the switch until the car powers up. Tighten the 2 mounting screws and check for functionality in all the switch positions.

A few months ago, I was having a hard time starting up my car. I took it to a few repair shops and they thought the problem was a bad starter. Then I took it to Firestone and they diagnosed it as a bad neutral safety switch. Finally, after having the problem for several months, my car refused to start.
Firestone ordered the neutral safety switch, easily installed it in a day and the car is starting up just fine. The neutral safety switch is what keeps the car from starting until you push down on the clutch.
I have a 5 speed, manual transmission,  Thought I would share this just in case there are others that might have the same problem.

Way to go Susan!!  You may have hit the nail on the head!!  Keep going, Joey will make a mechanic out of you yet!!