News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

Neutral Safety Switch and Reverse Lights

Started by Gary Christensen CLC # 21112, July 25, 2011, 06:48:45 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Gary Christensen CLC # 21112

Can someone explain how the neutral safety switch works?  I can't figure out how it "knows" what gear the transmission is in.

Mine has been bypassed by someone in the past, so I'm guessing it's broken.  But the other thing that doesn't work is my back-up lights.  I'm wondering whether these two failures might be related, since they both rely on knowing what gear the car is in.  If they're not possibly related -- I'm waiting on a new neutral safety switch unit -- then I'll start tracing wires back to the rear of the car.  (I already checked the bulbs, with my fingers crossed).

This is all happening as part of my continuing saga of rewiring the dash, seat, and window harnesses.  Fun.

Thanks.

Gary

Jeffrey Burland

Yes, the BU lights run through this on some also. What year are we talking about as I have some 60-73 switches. thanks, Jeff in CT
Jeff Burland, Just one guy with too many 54-76 restorables and parts to list
https://www.facebook.com/WillingtonCadillac/

Gary Christensen CLC # 21112

Usually I put that I have a '62 Eldorado in the subject -- don't know why I didn't this time!  Duh.

The Tassie Devil(le)

G'day Gary,

There is a lug on the concave part of the switch that goes into the Steering Column, and this lug mates with a recess in the gear selector tube that extends from the gear lever to the bottom of the column.

So when moving the lever from Park, through to Reverse, the lug is moved within the switch to operate the various internal contacts that operate the parts of the Neutral Start Switch, Reversing Lights, and also the Vacuum control to release the Park Brake.

The Neutral Start operation opens the contacts when in any gear, so that the Starter Motor will not crank, and therefore start the engine.   When in Park or Neutral, the contacts are closed, enabling the operation of the Starter Motor.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Chris Conklin

I think Bruce covered the operation. If it's similar to the '66 NSS, you pin the switch in place with an Allen wrench when you install it with the trans in the neutral detante. That aligns the switch with the gear selector. It may take some finessing and don't be surprised to hear a vacuum leak once done. If you trust the switch, the regulator at the brake is the leak.
Chris Conklin

The Tassie Devil(le)

I always make sure that the gear selector is in "Park" and then make sure that the tab is in the corresponding position before inserting it and fastening it down to the column.   But, whichever way you go, make sure that it fits correctly.

I have seen switches installed and the lug not in the correct position, and then snapped off the first time the gear selector is moved.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Gary Christensen CLC # 21112

Thank you for the info.  Now I know why I couldn't figure out how the thing works -- the tab is (cleanly) broken off on my neutral safety switch.  As a result, I couldn't see any way for the switch to know where the gear shift lever is.

And now that I understand the mechanics of it, I also see that the broken tab is the reason for no back up lights.  Since the tabless switch never moves over to the right, the circuit for the back up lights is never connected.

I have learned a lot through this rewiring project.

Thanks again!

Gary