Neutral Safety Switch Mod

[Kiko]

My 83 G-Body Grand Prix has been substantially modified. When I changed trannys, I removed the rod from the linkage on the 700R4 that goes to the bracket under the hood near the firewall, that physically moves the Neutral Safety Switch/Back-up Lights lever on the steering wheel column.

However, I would like to rig-up some sort of "micro switch" inside the floor mounted shifter on the gear selector detent (or other (?) solution), to have a neutral safety capability. In other words, instead of a physical movement of the NSS on the steering column, I would like to use a relay/micro switch to make or brake that electrical connection.

Has anyone done this? I'm open to any solution or ideas.

Thanks in advance,

Andry

 

[joe_padavano]

Has anyone done this? I'm open to any solution or ideas.

Yeah, the factories in the 1960s. Once the locking shifter was mandated by the Feds starting with the 1969 model year, the console-mounted switches were phased out. You should be able to find aftermarket neutral safety and backup light switches that you can adapt. Note that most of these do not have the current carrying capability of the factory switches and require a relay to work properly. Also note that your car does not have an electric neutral safety switch. It has a mechanical interlock in the column that prevents the key from rotating to the START position unless the shifter is in neutral or park. You will need to splice into the starter wires to use an electric neutral safety switch. Also, with the backdrive linkage removed, the sleeve inside the steering column that works this mechanical interlock can vibrate out of position, preventing you from starting the car. I usually drill a small hole through the outer jacket and the inner sleeve and pin them together with a self-tapping screw to prevent this.

 

[Kiko]

Joe,

Thanks for that good description. I know exactly what you mean, since I dismanteld the complete car during the restoration/mod process. I took apart the steering column and know that there's a mechanical interlock on it to make electrical contacts for the Neutral Safety Switch (NSS) and Backup lights. The NSS used to be physically activated by a rod that was connected via a linkage to the transmission shifter under the car. That rod is what I removed.

I retained the NSS/Backup lights connector on the steering column. There is still a physical connection via metal rod to the ignition switch. What I would like to do is rig up my shifter detent in the console so that when I shift, I could activate those electrical connections in the NSS/Backup lights connector.

My thoughts are to mount two "micro switches" on the shifter detent, which would be physically activated when I move the gear shifter from gear to gear. The micro switches would be mounted in such a way that one would make electrical contact when the shifter is in the park and neutral position, to activate a relay that would connect the ignition wire; and the other would make electrical contact when the shifter would be in the backup positon, to activate a relay that would connect the backup lights.

What are your thoughts on this approach? Anyone else, please feel free to chime in with suggestions and/or recommendations.

Thanks,

Andry

 

[Kiko]

Judging by the lack of feedback, I guess I'm about the only one that'll be attempting this kind of mod. Oh, well. I'll let everyone know how it works out.

In the meantime, if anybody has any thought, please let me know.

Andry

 

[FE3X CLONE]

I've installed aftermarket shifters but found it easier to keep the rod and linkage from the steering column like the factory had it to keep things as simple as possible.
For my T56 I just cut the back up light connector off the dash wiring and wired in the new plug that runs directly to the trans.
You should be able to do something similar with your wiring except you'll have your wiring going to the micro switches instead.
For the neutral safety you could splice into the large purple wire on the steering column and run a wire to each side of the micro swtich. The only problem, like Joe mentioned, you'll need to make sure your switch can handle the current.
Joe pretty much nailed it on the head.

 

[85olds4spd]

maybe try a switch like this. Just make a bracket so it hits the shifter when in the neutral spot.

 

[joe_padavano]

Joe,

Thanks for that good description. I know exactly what you mean, since I dismanteld the complete car during the restoration/mod process. I took apart the steering column and know that there's a mechanical interlock on it to make electrical contacts for the Neutral Safety Switch (NSS) and Backup lights. The NSS used to be physically activated by a rod that was connected via a linkage to the transmission shifter under the car. That rod is what I removed.

Actually, no. There is no electric NSS in the starter circuit in your car. The switch you saw was the Park/Neutral switch, used by the ECU to help set idle speed. It looks like the old-style electric NSS but that is not what it does. The starter interlock is a completely mechanical feature that acts on the rod that goes from the lock cylinder to the ignition switch. Even if you spliced into the wiring on the Park/Neutral switch, it would not prevent the car from starting. If you do install an aftermarket NSS switch on your shifter, you will need to splice it into the wire that goes to the "S" terminal on the starter solenoid.

 

[Kiko]

To all,

First of all, thanks to everyone for chiming in. Lots of good points that I'm chewing over!

The microswitch pictured is what I was thinking about. I will most likely use the switch to provide a ground to a relay. That way, I won't be running any high current wires throughout the car.

Joe,
Your explanation makes sense, and after thinking it over, I realized that you are correct regarding the NSS. It's the ignition switch lock cylinder that pushes a rod that allows the engine to be started in either neutral or park, only if the linkage from the transmission is in the right position (i.e., only when the transmission is in Neutral or Park). I don't have that linkage any longer.

Since my car does not have an ECU, I don't think that the steering column interlock does anything other than provide a circuit for the backup lights.

I guess that the rod from the ignition switch lock cylinder is no longer required. The microswitch will be used to make/brake the purple wire connection. Hence I will need two microswitches; one for the Neutral stick shift position and another for the Park position. I will also need a third microswitch for the Backup position.

Does my interpretation make sense?

Andry

 

[joe_padavano]

Joe,
Your explanation makes sense, and after thinking it over, I realized that you are correct regarding the NSS. It's the ignition switch lock cylinder that pushes a rod that allows the engine to be started in either neutral or park, only if the linkage from the transmission is in the right position (i.e., only when the transmission is in Neutral or Park). I don't have that linkage any longer.

Since my car does not have an ECU, I don't think that the steering column interlock does anything other than provide a circuit for the backup lights.

I guess that the rod from the ignition switch lock cylinder is no longer required. The microswitch will be used to make/brake the purple wire connection. Hence I will need two microswitches; one for the Neutral stick shift position and another for the Park position. I will also need a third microswitch for the Backup position.

Does my interpretation make sense?

Andry

I apologize in advance if I'm misreading your response, but what you wrote still doesn't sound quite right.

Just so there's no confusion, there have been two rods discussed. The first is the rod from the lock cylinder to the ignition switch. This rod is internal to the steering column and is mandatory. The second is the backdrive rod from the trans to the tab at the bottom of the steering column. The backdrive rod rotates a shift tube inside the column as you move through the gears. This rotation serves several purposes. First, it locks the trans in park when the key is removed, which is a federal requirement for car manufacturers. Second, it rotates a blocking ring inside the column that prevents the first rod from moving to the START position unless the trans is in park or neutral. This is the mechanical NSS function. Third, it slides the Park/Neutral switch into positions that either send the Park/Neutral signal to the ECU or close the circuit for the backup lights when in reverse.

Removing the backdrive linkage obviously disables all these functions. This is not a problem, but as you noted, you need to come up with a different way to perform both the NSS function and the backup light switch function. The rod from the lock cylinder to the ignition switch must remain in place. One thing to consider is that the shift tube in the column can inadvertently rotate due to vibration, preventing the key from moving to the START position. You have two choices here. You can drill a small hole between the outer jacket of the column and the inner shift tube and install a small sheet metal screw to lock the shift tube into place. Alternately, you can just grab the shift bowl part of the column and check to make sure it is fully counterclockwise before starting the car. This has the added benefit of working as an anti-theft device. Simply turn the shift bowl fully clockwise when leaving the car and the car cannot be started even if the thief uses a slide hammer on the lock cylinder.

 

[Kiko]

Joe,

Very good write up that clears up points that I did not express all that well. Thanks!

I like your suggestion for "anti-theft" using the shift bowl. I'm a bit concerned about your statement that "vibrations" could cause the shift tube in the column to rotate, preventing the key from moving to the START position. Vibrations would only occur if the car is driven, i.e., already in START/RUN position. When the car is parked, there would be no vibrations to move the shift tube out of position and preventing starting the car. If somehow the tube was moved, all that would be required is to rotate it counterclockwise (i.e., the "anti-theft" principle). Am I correct or is there something else that I'm missing?

Thanks for helping me out. :wink:

Andry