Neutral Safety Switch replacement (NSS) Failure? or something else.

[grim 140]

I replaced the NSS switch. Still not starting. I replaced the switch because I was having the same issues as everyone else. Not starting in park or neutral, move it around a bit and it will start. Finally one day nothing worked! So I jumped the two wires under the driver's side dash and it starts every time. So I replaced the switch! aligned everything as per the manual and still nothing? Still starts if I jump the two wires though!
Any ideas of where to start with this issue?

 

[gsxr]

Did you align the NSS during installation? Will it start if you move the shifter slightly away from the P or N detents?

 

[grim 140]

I aligned it and I tried moving the shifter around in different positions.
But I will say I didn't try moving it slightly out of the P or N detents.
I can try that tomorrow morning! I jumped the wires to pull in back in the garage for the night.
If that doesn't work what else to check?

 

[emerydc8]

No reverse lights, while in reverse, could be an indication that the NSS is out of alignment. Ask me how I know.

 

[gerryvz]

It sounds to me like a re-install / re-alignment is in order.

 

[grim 140]

Okay!! well no reverse lights and trying to move the shifter around ever so slightly did nothing.
So I guess I will double-check the alignment again. Let ya guys know later on, If I have success or not. Have to head to work now!

 

[gerryvz]

I recommend completely removing, and then re-installing and aligning the NSS. I recommend using an appropriate drill bit as the alignment dowel.

 

[grim 140]

Agreed! I will tackle that tonight!

 

[grim 140]

Okay, I decided to go to work late! I uninstalled and reinstalled the switch paying particular attention to the alignment pin and now the reverse lights do work but still no start? Only if I jump the wires! Is there a way to test the switch hooked up to the car but not bolted in?

 

[grim 140]

Or possible fuses!

 

[500AMM]

Okay, I decided to go to work late! I uninstalled and reinstalled the switch paying particular attention to the alignment pin and now the reverse lights do work but still no start? Only if I jump the wires! Is there a way to test the switch hooked up to the car but not bolted in?

Take a look at post #61:

HOW-TO: Replacing Neutral Safety Switch (NSS, S16/3) | "HOW-TO" Tutorial Articles

When I had the Trans Rebuilt on the C126and E500, they both got replaced. (no it wasn't URO) :stickpoke:

www.500eboard.co

If the NSS is new it looks like that inside, or better of course, and nothing can go wrong inside there except from misalignment. You can take the switch off and move it to the different positions and see what happens. However, incorrect function or a missing respons may not mean that the switch is defect, the switch does only distribute a signal to other control units and equipment in the car.

 

[grim 140]

I know it’s aligned correct. I cut a 4mm drill bit to size and put some tape in the hole so it does not slide out when installing the switch. Had to use needle nose pliers to get the bit out.
I’m just baffled? Reverse lights yes I do have. The shifter shifts smoothly through P-R-N and the rest. No binding!

 

[gerryvz]

I'm starting to wonder if the NSS you have, may be defective out of the box.

 

[grim 140]

Me to!
Wonder if I can pull the switch off the car and put the alignment pin in. Which should be neutral? Hook up the plug and see if it fires up. With the trans in neutral of course

 

[gsxr]

Schematic (link below) indicates you may be able to short sockets 7+8 at the NSS connector, and see if it cranks normally? If so, the NSS might be defective?

https://freescruz.com/.priv/W124/w124CD1/Program/ETM/2415200.pdf

 

[grim 140]

Those are the two wires I gator clip together under the dash. But I will try at the plug also!!

 

[emerydc8]

Are you making sure the connector at the NSS is correctly seated? There's a white ring on the switch that has to be rotated to lock it in place.

 

[grim 140]

Yes sir, it's locked and seated. The bushings look good too.
I'm going to mess with it some more this weekend. It has to be a bad NSS! I ordered the part from EEuroparts here is the link.

SHOP – eEuroparts

Select your year, make and model to find the perfect fit European car parts at the best price! | eEuroparts.com

www.eeuroparts.com

Just in case someone is interested!
I will keep everyone informed and if anyone has any ideas hit me up with them.

 

[500AMM]

If the switch is defective you should get a replacement switch from the dealer, hopefully without too much hassle, but it may take some days with return and get the new one. But out of technical curiousity it would be interesting to know what's wrong with the switch, are you going to do any further checking before going the return route?

 

[emerydc8]

Just in case someone is interested!
I will keep everyone informed and if anyone has any ideas hit me up with them.

So the new NSS is not working at all unless you jump the wires? Will it start with the old NSS reinstalled or do you have to jump wires on that too?

 

[gsxr]

I'll second the questions from emerydc8 above.

Normally I wouldn't order from eEuroparts but NSS 0005456206 is OOS at all the reputable vendors. Hope the threat of NLA didn't come true.

 

[grim 140]

I thought the NSS was not avail From Mercedes anymore?
The original NSS and new one won’t start unless jumped with the wires. I am going to experiment this weekend and also I am in process of setting up a return on the new NSS.

 

[gsxr]

The NSS is showing NLA at RevParts dealers, but you could always call a dealer and inquire. MB Classic shows no results which is a bad sign.

If you can start the car while jumping the wires under the dash, but NOT when jumping the wires at the NSS connector, you have a wiring problem. If it starts when jumping the NSS connector sockets, you could have two defective NSS's, which seems unlikely...

 

[Vinnie]

If both NSSes turn out to be invalid, then you may want to buy from this seller on eBay:

Occasion-Lock-Reverse Light Switch Gear Automatic Transmission for Mercedes-Benz | eBay

Those seem to be the original MB parts, with the "Mercedes-Benz" brand text erased on the plastic part. I'm afraid that those may be the last 8 units on the world...
A few months ago I was told at the dealer that because of covid, the income Mercedes earned was low, so the company introduced cost cutting where possible. Besides, Mercedes invested A LOT into the new electric cars factory. That means that money for the classics division is on the very end of MB's current expenses. That might explain why Dave found no results for that part at MB Classics...

 

[grim 140]

I will definitely report my findings with jumping from the NSS socket.

 

[grim 140]

I'm trying to see if there are any fuses between the NSS and starter?
Does anyone know? I'm not seeing anything. Getting ready in a little bit to see if I can jump the wires at the NSS switch plug!

 

[emerydc8]

Post in thread '1994 E500 won't start - due to alarm or radio?'
1994 E500 won't start - due to alarm or radio? | Troubleshooting and Diagnostics

 

[gsxr]

Good point, Jon! Need to make sure the immoboliser is not the problem.

Assuming this is on your 1995 S500, I'm not sure where to look for this.

 

[grim 140]

Holy Crap!! I bypassed the K38 and jumped it per emerydc8 link and it fired right up!!
Also, the K38 for my year Mercedes 1995 S500 location is up behind the Passenger airbag! The K38 was replaced once before in 2001. There is a date stamped on it. So do I replace the K38 or leave it permanently jumped with the alarm box unplugged? Thanks to everyone for your help and input!

 

[grim 140]

Well never mind! I'm gonna leave it bypassed and go from there!

 

[gsxr]

Glad you figured it out! And that you didn't get a defective new NSS.

Is the old one usable or is it still dead?

 

[grim 140]

That's my next thing to do is test it out.
Let ya know soon!

 

[grim 140]

Well just reporting that the old NSS is definitely bad!
Also, everything is else good! Took it for a good ride down some country roads!
Once again thanks to everyone for their help!