My 78 280Z Starts and Runs Great But... Ignition Switch Issue Switch?

[FlyingL]

I have a bone stock 78 280z that I have had for about 20 years. About a year ago it would just stop running like someone shut it off. If I waited 15 minutes it would start and run great again, I thought it might be the ignition relay and changed it but it didn't help.  The first time you start after re-attaching the negative battery cable  it starts and runs great,  When I shut it off the red brake light in the speedo comes on and so does a little red light in the ammeter that says charging. I can also hear a humming noise that I think is the fuel pump.  

 

I think it may be the ignition switch is not turning off the contacts it should. I bought a new ignition assembly but haven't installed it yet.  Could a simple adjustment cure the problem? There is another ignition switch component  that you can buy at a parts store that I read about in some posts but do not know where it is located. Ant suggestions will be greatly appreciated!

Thanks

[NewZed]

4 hours ago, FlyingL said:

it would just stop running like someone shut it off. If I waited 15 minutes it would start and run great again,

 

This part sounds like a failing ignition module.  They overheat and stop working then start working after they cool off.  Often they will stop working after getting the engine up to higher RPM.  That's one way to test it, run it up to high RPM, watch the tachometer needle for weird behavior and see if it keeps running.

 

4 hours ago, FlyingL said:

When I shut it off the red brake light in the speedo comes on and so does a little red light in the ammeter that says charging.

 

This part is normal.  Those lights are supposed to be on when the engine is not running, but the key is on.  They should both turn off when the engine starts.

[FlyingL]

The lights stay on when the key is removed. They do turn off when the car starts. So each time I shut the car off I take the negative battery connection off. If I don't it drains the battery completely.  Where is the ignition modules and does it have anything to do with the ignition key mechanism? Are new ones available? I appreciate your comments.

 

Thanks

FlyingL

[jhm]

Yes, replacement ignition switches are available.  You can buy new, from a vendor like MSA Auto; or you can find a good used one from a donor car.  I've had them fail, and it's an easy replacement/fix.

 

https://www.thezstore.com/page/TZS/PROD/classic10e07/12-4208

 

To test the switch, this is what the continuity should look like with the key in various positions: