727 Neutral Safety Switch

[kezammit]

Just bought first Mopar, 68 Coronet 500 383 4bbl with 727. Will not start with key, tracked it down to the Neutral Safety Switch. By adjusting linkage, I was able to get the switch to close (ground) in neutral, and car starts with key in neutral. But I cannot get switch to close in Park. I even tried removing the linkage and moving the transmission lever through the full range of "Park" stop with no luck. Is there a way that the "follower" inside the transmission can fail so that switch works in Neutral but not Park? Easy fix, or should I just go ahead and pull the thing and have it rebuilt?

THanks!!!

 

[Meep-Meep]

Should be easy to pull the switch and check it with an ohm meter. Another thing you can do is check the shift valve actuator on the valve body (the thing with the detent) and see if it has excessive clearance. I have seen them worn out. It's possible that the pressure from the park pawl is throwing the actuator out of alignment with the switch when it's in park. Either way you should not have to pull the trans to fix it.

 

[kezammit]

I think the switch works, since it functions correctly in neutral (and I metered to verify). If I remove the switch, is there a way to check for excess actuator clearance through the port, or do you have to remove the pan to assess that?

Thanks for your help!
Kent

 

[69 Runner]

Neutral safety switch was one of the odd things on Mopars (unlike starters which were basically interchangeable across the board). There are switches that LOOK the same that aren't, and when installed they won't work properly. I went through this once many years ago, and I think it involved the one wire incarnation.

but it's been to long to remember for sure

 

[kezammit]

Yep, this is a single wire switch, and when I ordered a replacement, they sent me the three wire version. I know that is wrong, because the wiring harness is single wire, and there is a reverse light switch on the console shifter. Will pull the switch and see if the distance to the actuator is the same when in park and neutral.

The good news is I can start the car in neutral without getting out and popping the hood!

 

[Meep-Meep]

You should be able to give the shift arm a good yanking about and watch for movement through the hole.