W126 Neutral Safety Switch
 

Ok, pretty sure this is the issue. Just want to be sure. About a month ago I had a no turn over situation. After much ado, it fired up fine. Never to happen for a while, I ignored the problem as a one-time event.

Now in the past week, with very high temps and a very cold garage, I have having this as a daily issue. No crank at all. I try several things and several keys. What I have noticed it that if I shift all the way to first and slowly back to neutral, it will usually start in neutral. Not in park. I learned this one owning a Mark VIII. On the Mark, this would be the neutral safety switch, aka the manual lever position sensor.

Can I assume its the same issue with the 560? If so, can I assume its also an external part that will not involve fluid loss? And also if so, its it pretty easy to replace? Or clean if replacement is not really required on these?

Thanks!!

Sounds like the neutral safety switch. This happened a while ago in my 300SD. It was a pretty easy replacement. No fluid loss. Must have been 5-6 years ago. Eventually it got to the point where it wouldn't start in P or N, so I just carried a 14 gauge wire and jumpered the starter until I got the replacement in..

Could be. You might try holding your foot on the brake, turning and HOLDING the key in start , then moving the gear selector and see if /where it starts.

Ya, its the switch. New OEM is only $11, so ordered one. Its really got bad FAST. What I found was that if I hold the key to full stop and jiggle the shifter in neutral it will start. And now I had a no-start after work. So its no longer after long cool downs.

Did much more digging. Replacement seems easy but in a tight location. Guess I will be doing a lot of little things this weekend!

Linkage Grommets
 

If the plastic grommets are worn out it can affect the starting of the car also..

I just replaced my NSS a few weeks ago. I found a great tip here in the DIY section that was extremely helpful, and it will eliminate multiple adjustments: Instead of aligning the bracket with the alignment hole on the body of the NSS, turn the ignition on and move the gear selector into Reverse and watch for the back-up lights to come on. Once they´re on. set the NSS at that position. It´s a whole lot easier than the MBZ suggested way.

Just an update. Had the switch for a while, but finally had some time to install it.

All bolts/nuts are 10mm. Space is tight but I found the 1/4" sockets/ratchet worked well in the tight spaces. It really looks worse than it is.

The bolt/nut holding the shift linkage in place must be removed. The arm is grooved for the bolt in the event the nut come off it will still hold in place. Like may upper control arm bolts where they interface to spindle.

The white collar that turn simply hold the harness end in place. To remove you want to turn upward then pry out harness plug. Install is reverse of course.

When installing, just make sure the black lever is in the same position as the original and reinstall should be easy as cake.

I did not have to align anything and now she fires right up without having to mess with the shifter.

how do you determine if its the nss or the ignition switch?

HA, this is the way I installed mine too. I figured everyone would think of this... if not, this is the easiest way to do the job.

For me it was related to shift lever position. Since I could put it in neutral and, with key turned to start, slowly shift into reverse to get it started. At first I thought it was ignition. If it was ignition the car may start randomly, but if you dont touch/jiggle the shifter then I would suspect the switch.