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Inside the Neutral Safety Switch (or Transmission Range Switch)

48K views 21 replies 10 participants last post by  hashwood 
#1 · (Edited)
Inside the Neutral Safety Switch (or Transmission Range Switch)



Hello All,

In my quest to keep the kid’s 94 900NG running I found myself elbow deep in the engine bay pulling out the Neutral Safety Switch (NSS). We have been having problems with it and I thought it was time to take a stab at it. I had read here that others were installing bypass switches and the like and I was prepared to do the same but I thought first I’d take a look at fixing the darn thing. The one thing I new for sure was that I wasn’t going to pay the $300+ for a new one.

The problems started with the usual not being able to start the engine in PARK. We would have to put the shift leaver into neutral to get the starter to turn. Eventually that procedure no longer worked and we had to modify the starting procedure to the following: First put shift lever in Neutral; then turn the key to start and hold it there; And Finally jiggle the shift leaver in Neutral until starter engaged. WOW!

Today I pull the darn thing out and carefully disassembled it. What I found inside was interesting. The good news is that these switches are easily repairable! :cool:


To remove the switch you have to:

Remove Battery and battery tray.


Remove Auto trans fill tube (clean dirt and grime away from base of tube first so grit and grime do not fall into tube hole in transmission housing)
Unbolt various hose clamps and push hoses aside to make room for fat hands to get into switch area location

Remove nut that hold shift selector cable plate onto the NSS and lift cable plate off NSS.

Remove large nut below shift plate along with retainer washer and rubber washer (retainer washer has bend up tabs to lock large nut in place – I think this nut is only snugged when reinstalling and then washer tab is bent up to hold it –that’s what I did anyway).

Remove right and left fasteners that hold the switch in place and pry switch up off transmission shaft – It doesn’t take much force but there is a “snap in place” feature that must be overcome.

Finally unplug the two electrical connectors and cut any tie straps to get wires free. Study the connectors to make sure you understand how they come apart since there are locking features. We don’t want to break those features off now do we? ;)


At his point the switch should be in your greasy, grimy, grubby hands! :cheesy:

The switch is fairly easy to take apart. There are 5-6 Phillips head screws on the under side that need to come out. I had to use a vice grips on one of them but they all came out.

Next take a file and pliers to the two sheet metal tabs that are swedged to hold the wire shield in place. While it looks like two of the screws hold on the lower half of the shield leave this piece in place. You have to get the other half off to split the switch housing open.

Once opened, you’ll notice the rotational contacts inside. There is a rotational arm inside with 3 spring loaded contacts. These contacts slide (or wipe) along the other switch housing half which has copper rails potted into it. The wipers conduct across a pair of bars closing the circuit.

Please see photos.

What I notice in my switch was that the contact grease had become hard and tack. The last contact, furthest from the pivot point, was actually stuck down into the leaver arm and did not appear to be making contact. This last contact looks to be the one which tells ECU what shift leaver position is in.

I cleaned every thing up. Lightly sanded the copper rails (600 grit). Reinstalled springs and contacts into leaver arm (note that 2 of the springs are connected- you’ll see what I mean). Greased everything with a generous amount of bulb grease and put her all back in place and …… Walla,... starter cranks in “Park” every time.

It was not that difficult to do and should be able to be accomplished in a Saturday afternoon.

I hope this helps!

Brian

94 900ng

2003 93 conv

1973 Jensen Healey

1997 F250 Power Stroke Diesel Crew Cab

2001 T&C Mini Van (for Sale)

1974 TVR (Project car - just sold but still parked in my garage):confused:
 

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#4 ·
Shift cable troubles

The saga continues.:(

I've been getting the "check Gearbox" light and suspected it was more trouble with this Neutral safety switch (auto matic trans). I thought the switch body needed further adjustment or maybe the internal contacts were mucked up? After messing with it for the last few days I've discovered problems with the gear selector cable. The plastic housing at the end where the thing connects to the neutral safety switch has shattered. There are pieces of it lying on top of he transmission housing. With out the support of the plastic housing the cable seems to be buckling when the shift leaver is pushed towards park.

I’ve checked eEuroparts.com for this cable and can’t find it. It looks like I’ll have to try to find a used cable or possibly fabricate some thing?

Any thoughts?

Thanks,
 
#6 ·
Thanks for the reply. Dealer only = expensive?
First I'll try the fix pictured below?
The cable had a bend in it which I straightened before taking the shot.
I trimmed away the jagged plastic but saved the ends. then took a piece of fuel line and slit it and tie strapped it in place. It's a bit crude but may work. I'll find out tonight.
This would explain why gearbox light has been coming on. Park sensor tells computer shift lever is in park but neutral safety switch tells it that it is not quite there.

Brian
 

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#8 · (Edited)
You and I will have to disagree on your last statement. Many of the cars I've worked on are old enough that parts are no longer available. I see nothing wrong with fabricating solutions rather than running to the dealer and forking over cash every time a part breaks.

It won't take much restraint to prevent the short section of shift cable from buckling.
 
#9 ·
Hey that is a great fix in a hurry :D

I kept a link to your DIY Neutral Switch repair That was a very good posting.

BTW, Diosnoche wasn't being rude he just didn't want you to get stranded :D

Diosnoche is a very knowlegeable SAABer and is of great help to many over here. He's a great asset to SAAB Central :cool:
 
#10 ·
Yeah sorry if I came off as being rude, but from my point of view, I see this prat as being so simple, yet something so important, I wouldn't want to get stranded one day when I didn't have any extra tools or parts in the car with me.

When I got my Saab the Accelerator linkage cable was kinda loose, it looks similar to the same cable on the transmission. Then one day we're driving along, I enter the highway and all of a sudden the accelerator just became loose, and I rolled off to the side. The cable had broken off the throttle body and I was left on the side of the road. Something so simple can cause a delay when its not wanted. Thank god I was able to rig it to the cruise cable on the side of the road to get me going, but what an inconvience.

But you have to realize how much pressure that cable is under when you shift the gear shift through the gears, it will eventually let go. You can try it yourself with the car off, move the arm that the cable attaches to by hand, it has clicks and will take a bit of effort.
 
#11 ·
briankelly said:
That was rude! :nono;

You and I will have to disagree on your last statement. Many of the cars I've worked on are old enough that parts are no longer available. I see nothing wrong with fabricating solutions rather than running to the dealer and forking over cash every time a part breaks.

It won't take much restraint to prevent the short section of shift cable from buckling.
I must agree with Brian on this one.
Often times a component can be repaired using "spit and duct tape" which can, if done by an expert, be better than the original. ..And, from the viewpoint of an accountant, far more expensive.
Viewed by a purist, this can be simply wrong, that only OEM should be used...
Viewed by a realist, this can be the only way......
"spit & duck tape" means fabricating, welding, using epoxys, over building,etc..
 
#12 ·
When you were having trouble with your neutral switch on the gearbox and the gearbox check light comes on , do you experience trouble on pulling away like its not in the correct gear then bump and its away and no more problems. This is until the switch acts up again by either not starting in park or neutral or the check light comes on. Its like the gearbox has got mixed up to what gear its in. I gather when the light comes on it puts the box in a high gear :confused: so could this be the problem. Plus how do you set up the switch again. I have set it so the car starts in park & neutral & the reverse lights come on when in reverse. I cannot try running the car as i have the turbo off for a rebuild and decided to do the switch at the same time as i was fed up of the light coming on and having to turn off and start up again. Oh i have had the gearbox checked and serviced. sorry for taking your thread bash
 
#13 ·
bash said:
When you were having trouble with your neutral switch on the gearbox and the gearbox check light comes on , do you experience trouble on pulling away like its not in the correct gear then bump and its away and no more problems. This is until the switch acts up again by either not starting in park or neutral or the check light comes on. Its like the gearbox has got mixed up to what gear its in. I gather when the light comes on it puts the box in a high gear :confused:
Its call "Limp Home Mode" the transmission defaults into 3rd gear.
 
#14 ·
Hello All,

It’s been a while. I thought I should follow up.

My first fix didn't quite work. The rubber hose I tie strapped over the end of the cable flexed too much and the result was not being able to push the shift lever (on the tranny) into park.



My second attempt worked better. I fabricated a 2 piece clam shell out of a small wood block which could be clamp over the end of the cable to hold it more rigid. With this block in place I was able to shift through all the gears and into park. However some of the times I shifted into park the Check Gearbox Light would come on. My next step would have been to mill a small, 2 pc aluminum clamp type part to install over the cable end had the CGL not come on.



Backing up a bit, I had a number of problems occurring at the same time. I had the neutral safety switch go bad which I disassembled, cleaned and reinstalled and I had the plastic end of the gear selector cable break which allowed the cable to buckle there by causing a problem with gear selection. I was having difficulty resolving which problems were being caused by which failure. By coming up with a temporary fix for the cable I was able to regain confidence in the NSS fix. After talking with a service tech at my local Saab service center I bought a new cable since the old one may have been stretched. I will install this and hopefully all the problems will be solved.



The cable was not that expensive ($115) but I wanted to avoid the hassle of tearing into the shift consol. Well looks like I’ll be doing it any way.



BTW Bash, to position the NSS my manual says that you put the shift selector in “N” and then rotate the NSS on the tranny so that the pointer on the shift bell crank is positioned on or centered on the rib which is cast into the top of the NSS.



Diosnoche, sorry I took offense to your comment. The fact alone that you are here on this board means your intentions are good. I just like to try a few things first before spending the cash on new parts.



I’ll get the cable installed over the next few days and post a follow up.



Thanks for all the help.
 
#15 ·
More Problems

I've installed a new Gear select / shift cable. It was $115 from the dealer and it is a Dealer only part. Replacing the cable is a bugger since the all the plastic has to come off the shift consol. I found that removing the internal air duct that directs air to the rear of the consol was helpful because it gives you side access to the lower end of the gear select lever.
So new cable is in and all seemed well for a while. Now Check Gearbox light comes on when ever selector is moved to park. This is very repeatable. If we turn off engine and move shift leaver back and forth thru all positions and then back to park, release brake and restart engine the light goes out. Selector can be moved to reverse or drive with no light but light almost always comes on when it is moved to Park.
I have the Neural switch aligned such that when selector is in "N" the finger on the selector cable bell crank is centered on the rib which is cast into the top of the switch (per Hayes shop manual).
I'm going to pull the neutral switch one more time and re-clean the contacts. I will also stretch the contact springs a bit to put more force on the contacts.
I'm wondering is if there is a problem with the park interlock switch?
If re-cleaning the neutral switch doesn't fix the problem then I'll spring for a new switch ($300) and install that. If that doesn't fix it then the car goes in to the local dealer! The logic being that I knew the cable was bad so installing that myself saved me 2-3hrs of dealer labor. Also, they charge $90 more for the neutral switch than eEuro does plus 3hrs labor so I will save on that as well.




Here goes! :eek:

Brian
 
#16 ·
Today I removed the Neutral safety switch again and opened it up. I found the dielectric grease (light bulb grease) I had used had turned green (tarnish from the copper)? I cleaned it and used petroleum jelly instead.

Also I sanded the copper tracks with 600 grit and filed the tops of the 3 contacts flat (they were pitted). I stretched the springs ever so slightly and I reassembled everything. It now looks like problems are solved. I can not get check gearbox light to come on.

Hopefully this will be the final fix. :)

Brian
 
#17 ·
Congrats on the repair, and thanks for the info and great pics!

I think I'll be undertaking the same procedure soon, although my problems are cold-start issues as opposed to no-start issues, but the dealer and his tech2 said it's probably the NSS... It's a 12yo car so I'm sure a good clean of the switch wouldn't hurt.
From the look of things it's a very simple procedure, if a little fiddly. It's surprising a clean and re-grease job on the switch isn't standard workshop practice, as it looks far simpler than many other procedures commonly undertaken. (I wonder how many dodgy shops do clean the switch and charge you for a new one?)

Cheers,
Andrew
 
#18 ·
Three weeks later and still no problems. I wish I could get my hands on all the good NSS's that have been thrown out. I bet one could make a pocket full of cash by "reconditioning" them.



Now it's on to front axle replacements. I could hear them knocking as my daughter did a u-turn down in the end of the cul-de-sac the other day. I replaced the boots on one last year.

I bought two replacement front axles from eEuro and they were waiting for me on the front steps when I got home from work yesterday. I also bought a new belt idler. Looks like car will be down for a few more days.


Brian :D
 
#19 ·
One thing to keep in mind for 'stealership' only parts - call eEuroparts directly - Drew has gotten me quite a few things not listed on his site - but stealership only - for less than the stealership. I call with either the part number - or when feeling cruel - make him look it up ;) - either way works out usually :cheesy:
 
#20 · (Edited)
I just pulled and cleaned my NSS, it was pretty gunked up, so hopefully my issues will be solved.
My car ('96 900 V6) had a lot of crud in the way, worst part was some steel piping (think it was part of air con) that was impossible to move, I could only just pull the switch past it to get it out, it was a pretty tight squeeze.
I happenned to break the same bit of plastic tubing on the gear cable. fixed mine with a bit of lathed up aluminuim bar stock and a couple of hose clamps. Hopefully wont have any issues....:confused:
Managed to get away with not completely removing the ATF dip stick, so didn't have to worry about crud falling in. It had to be partially pulled out to get it off the bolt, but then I just turned it out of the way and pushed it back into the transmission. It was a bit annoying to work around, but better than junk falling in the transmission.
My base battery pan couldn't be removed either, it's part of the chassis, was pretty hard to get past.

Found a broken vacuum hose as well, not sure if it was already broken, or if I broke it myself, turned out to be part of the secondary air intake system for when it's cold, so if it was already broken then it'd also contribute to my cold start issues. The hose was pretty fragile feeling, I'll have to find some replacement hose asap.

Thanks again for showing that a switch clean can be done. it was a heck of a job getting the switch out, but I think it'll be worth it. Certainly better than a new one and breaking the bank.

Andrew

**Update - Using this information, my NSS is in perfect condition, I haven't had a single check gearbox light since the fix.
 
#21 ·
I know i'm bringing a dead thread back but I wanted to contribute that I found this thread while searching for how to remove and clean the NSS from my '01 9-3. Everything here is great advice for getting it out, but found that on my NSS the screws had been replaced by rivets. Why? So you need to pay for a new one I assume.

Found this thread in the 9-5 forum suggesting to drill out the rivets/cut the heads off and replace with machine screws upon re-assembly:

http://www.saabcentral.com/forums/showthread.php?p=1764117

Good to go
 
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