Replace Ignition Cylinder or install Push Button Start?

What does the key not do? Is the tumbler section or is it the switching section that is bad?

 

It is very likely your wiring module behind the lock tumbler that has gone bad. That module is fairly easy to change and it is still available from Gt Carparts. Do that.

 

I am betting Mitch is correct. That fits the scenario of a broken switch, not a broken lock.

Do not install one of the aftermarket switches. They are easy to get and less costly but are cheap, unreliable junk. Get either Bosch or SWF brand.

I have not bought one in a long time but T Rutlands used to have both in stock.

 

Once you get the new switch, be sure to install a diode to protect the contacts to the starter solenoid. I do this for my Ferrari and Alfa.
Per John Corbain Dino 246:
"Drove the car for another 25,000 miles and the problem came back. I pulled the switch, carefully unriveted it and found the brass starter contact badly eroded. Pulled contact, brazed some rod on contact, filed to original shape and put back together. The hollow rivets can stand 2-3 re-workings. Took that many tries to get contacts and 1-time lockout just right. Time to run an experiment. I touched the starter wire to the battery wire and admired the beautiful arc when I broke the contact. That was where the brass was going. A Flyback diode was needed. I put a silicon diode from the starter wire to ground, cathode to starter wire, and no more arc. When you break the current going to a starter solenoid, there is a huge negative spike and the energy in that spike was killing the switch. The diode catches the spike so no voltage, no arc. Just make sure the polarity is right and the diode is rated for 3 amps or more. Radio Shack is fine. I put everything back together and have run 100, 000 miles without a miss."

 

I have replaced a lot of those switches. Not once for a burned contact. Sorry but this sounds like a fix for a problem that does not exist.

 

I replaced two due to starter solenoid not picking up. I disassembled them and noted the destroyed contacts to the solenoid which were caused by arcing.
They are used in my instrumentation field in some applications for contact protection of switch contacts.
No need to be sorry, we each have our own experiences and act accordingly.

 

If you're worried about the current through the ignition switch (and it's generally a good idea to minimize it - that's why people do headlight relays) it's as easy and more effective to add a relay so that the solenoid current doesn't go through the switch.

 

You don't need to remove the whole thing if all you are doing to to change the switching section. Push the seat back (or remove it). Lay down on your back facing up at the assembly. Reach up with a small Philip head screw driver (I use a ratcheting driver) and remove two small Philip head screws from the back of the switch after you have unplugged all the wires (take notes of where wires go). Swap out the wiring module, replace the wires. If you have the right tool, it takes less than 1 hour.

 

Then you have a problem causing excess load. Probably should fix that instead of applying bandaids.

 

Oops, I was not specific on my two failures. My mistake. One was on my 32k mile 72 Dino 246 and the other was on my 66 Alfa Duetto with 100,000 km. Both had the same type of switch and same internal failure when taken apart. Contact was destroyed by arcing.
My 78 308 only has 18k miles and I installed the diode at 16k miles. I drive it at least once a week to Cars and Coffee.
I will see how long the switch endures. I have two German made switches on the way for spares. Bosch and SWF.

 

I have looked after hundreds in the last 43 years and that is a story I never heard. Not on a Ferrari.

 

For reference..
https://www.ferrarichat.com/forum/threads/dino-saga-071103-_-ignition-switch-2007.173384/

 

So what? I see bad diagnosis every day of the week. With what most good professionals see, if we didn't see it or one of our trusted mechanic friends didn't see it, it never happened. I see more problems attributed to the wrong thing than the right thing.

You can stop now. I will not be convinced. There is a mountain of really good, eyes on evidence.