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Neutral Safety Switch/Backup Light Switch

7K views 13 replies 6 participants last post by  SC Surfer 
#1 ·
I just replaced all the shift bushings on my 83' wagon, feels nice and tight, but...got in to start it and nothing. I've done some serious trouble shooting, took out that last rod bushing next to the switch from under the car, and reinstalled it. Also I've checked all the other posts on this subject but nothing comes up. It started fine before I began the project. Could it be an adjustment on the rod just below the shift lever? Also a post mentioned copper contact points inside the console, but I believe that refers to a manual shift. Should I buy a new switch? and if yes, why did it go out? Any ideas?
 
#8 ·
These cars have a single start ignition switch. Once you attempt to start it and it doesn't, you have to "reset" it (turn to position 0, and try again). Holding it in position 2 to start the car while pulling the gear shifter to the different gears will not work.
 
#4 · (Edited)
I'm about to change all the shifter bushing in my wagon as well... yours is Auto, right?

Here's a helpful link... I found it by typing in "neutral safety switch" in the search function of this forum:

http://www.benzworld.org/forums/w12...l-switch.html?highlight=neutral+safety+switch

I think what might have happened is that you knocked something out of place when taking the bracket off the tranny to get at that bushing. BTW, do you recall what gear the car was seated in when you took that bracket off... it probably doesn't make a difference, as that bracket probably only fits on the receiver one way... thank you Hans...If not, then figure it out...

In any case, if you're lucky, you might just need to adjust the NSS... if not, then the switch could have been worn from years of being actuated by a linkage with worn out or missing bushings, in which case you need to replace the thing... hopefully your dealer can get you one quickly and for a reasonable price... I wouldn't go aftermarket with this item!

If you're in dire need of the use of your vehicle, and are like me (I don't mind having to pop my hood up from time to time to get going... who cares what the average guy thinks, cause he probably has no clue of how to get out of a mechanical jam, or doesn't mind spending exorbitant amounts for another, probably less qualified person to 'fix' his car), there is a procedure for bypassing the NSS function with a jumper switch in the link above, or the link posted in the first link... you either have one, can use your jumper cables, can get one from Sears, or can make your own using a some 12 Volt wire and a switch.. I think an interior lighting wall switch from Home Depot might work for you, but ask one of their electrical guys or an electrician about it... BTW, it's a handy thing to have around for a few other fixes. (tranny service, valve adjustment(though it's better to crank engine by hand...refer to MBUSA CDs for proper way)... starting your car when NSS leaves you stranded...)

Good luck, and let us know how it goes...
 
#5 ·
If I remember correctly that lever on the trans only goes one way. If it doesn't, pull the lever off and by hand put the trans in park. You wont be able to turn the drive shaft if it is in park, but make sure the parking brake is off. Once you have established park on the trans side put the shifter in park. Then check your linkage. It might be off. Dont make any adjustments to the rod. I doubt that putting new bushings in would through it that far off. I am sure it is something simple. Also, make sure the harness is plugged all the way into the neutral safety switch. Those switches get so oily down there they can really fail at any time. I would try turning the key to the crank position and be more aggressive with the shifter going through the gears. Don't go so slow. Go back and forth really fast. That has worked for me.
 
#6 ·
I noticed that the rod can be adjusted, but why would anyone need to adjust the linkage rod/replace it with a new one that needs to be adjusted? I read the Haynes/Chilton manual has directions for adjusting the rod, but the FSM doesn't... I'd imagine that if you were installing a new rod, you'd be able to use the old one to gauge how to adjust the new one, right?
 
#9 ·
Hey Pat, Mine locks out if you let go of it after you start it. If you hold it in the crank position and let go of the key it snaps back to the run position disengaging the starter. Then if you want to crank it again you have to turn the key to the off position and then back to crank. But while you are in crank isn't the switch trying to send current to the starter so why couldn't you slide the shifter through the gears. Its late so bear with me.:confused:
Jon
 
#10 ·
What was I thinking? Sorry it's also late and I wanted to help but just got tired. I wasn't sure about that last sentence I wrote :eek: I just found it difficult to visualize (two right hands are needed...)

Jon you have a good point. Maybe the threadstarter did something else while fixing the bushings. When I did mine, it was not a problem just dig in, clean, replace bushings, clean, reinstall, clean :D but I had to have somebody do the last one under the car since I have bad lighting at our underground apartment garage. I never adjusted anything, because if you did it might throw the alignment off. Maybe you ordered this:


Instead of these:


If the NSS went bad, either P or N should work but not both simultaneously. Maybe you unplugged the battery? Maybe when you parked prior, the transmission did not "catch" so it's reading off? Just an idea, step on the brake and release the E-brake let it roll a bit and see if you can start it that way in P or N.
 
#11 ·
there is a black wire that goes to the back of the tranny .......thats the switch wire and its easy to dislodge if you are ruff under there .....go under and find it......it will plug in on the passanger side in the very back as if you were the drive shaft going towards the tranny....it is easy to break too.
 
#12 ·
DieselKraut may have the best solution here, as I did get a little rough with those wires trying to get at that last bushing--I can't get to it until tomorrow but I am curious how that switch works. Looking at it from the garage floor I can't figure out if the shift rod is supposed to be connected somehow to the switch, manually activating it, or if it works internally. I'm just trying to see if I missed something when I put everything back together. I did roll the car back to see if Park was engaged, and it is. Thanks for all the advice.
 
#14 ·
I solved the problem, although I'm a little embarassed to admit it, but for the benefit of those who may encounter the same problem I'll humiliate myself and admit that the bracket that holds the shift rod and sits next to the neutral safety switch was installed backwards...easy to do since it fits both ways--anyway I reversed it and now it starts. What was important for me though, through this process, was to notice just how badly worn that switch was. The plastic was cracked and missing huge chunks. I'm amazed it even worked at all. So a new one is on order. Humbly, SC
 
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