Car will not turn off

[Hookemdmc]

My sons 96 mercury grand marquis will not turn off. I had to disconnect the battery and pull the 50 amp ignition fuse in order to shut it down. What I found is that the ignition switch is good, the problem seems to be with the plastic link between the key cylinder and the switch. Turning the key will 'push' the link in order to start the car but, the key cylinder is loose and will not 'pull' the link back to turn the car off.
My question is, without investing an arm n leg into the car, can I just install an additional toggle switch to break the white power wire supplying battery voltage to ignition switch?

 

[wrencher]

You would need one heck of a toggle switch to handle that kind of amperage.
I think it would be safer & better off to find the ignition switch lock cylinder housing & actuator links used.
There are multiple power wires coming into the ignition switch. Just killing one wont keep it from having a draw on the battery with the key left in the run position.

There has to be quite a few of these in the junk yard.

 

[Miakehl]

If the problem is in the switch or linkage head to your local boneyard of choice and pick up a unit out of any car from the same family.

If it's in the tumbler, just order a new ignition tumbler from your parts supplier of choice. You could get a junkyard unit but I wouldn't risk it. These usually don't get more than $100 and are actually really easy to install. The downside is unless you get a matched door and ignition set he'll have to get used to having two separate keys.

 

[bryanwheat]

You should be able to replace the damaged part, or just buy a used steering column at a salvage yard. You can also just unbolt the switch and actuate it with your hand.

 

[Hookemdmc]

Thank you for the input.
After doing some additional research I may have to go with Bryan Wheats suggestion for now and actuate by hand. Taking apart the column is a little intimidating. I thought I could get lucky and be able to some how make and break one common wire feeding the ignition switch.