Fix the Neutral Safety Switch or not? - PeachParts Mercedes-Benz Forum

byronnash · #1 02-22-2010, 05:20 PM

I took my 300TD that I've only had for 2 weeks to the MB dealer this morning to get the High Mileage Medallion form signed. When I went to pull it in, it wouldn't start. Battery was OK, but nothing happened when I tried to start, no click or anything. Since I was at the dealer, and I my car wouldn't start, I just left it with them to look at, cringing at the future cost. They just called and said that after fiddling with the shifter, they got it to start. He said it might be the neutral safety switch but wanted to check one more time in the morning.

Is the NSS something that I should let them fix or is it an issue that you can sort of work around? I'm totally new to these cars so I don't really know what's critical and what's not. I am prepared to do simple repairs myself(put a new throttle linkage on this weekend) but I'm not sure I can handle anything super serious myself. Any advice on this situation would be appreciated. I am sure at this point, I am stuck with the diagnostic fee for having them look at it.

Thanks!

lorainfurniture · #2 02-22-2010, 05:29 PM

My 300e has the same issue.

Simply starting the car in "N" will avoid future problems.

Imagine if a car thief tries to start your car... in park.

snookwhaler · #3 02-22-2010, 05:58 PM

I would put my money on the shifter bushings before the NSS.

byronnash · #4 02-22-2010, 07:50 PM

So you can always circumvent a NSS problem by starting in neutral? I'm assuming this is the problem but I guess it could be a couple of different things relating to the ignition.

byronnash · #5 02-23-2010, 10:32 PM

Well, the dealership only charged me half the normal $139 diagnostic. They fiddled around with the shifter and chalked it up to an intermittently failing neutral safety switch. I guess it could have been worse and now I know what to do when it acts up again.

85chedeng300D · #6 02-23-2010, 10:47 PM

The next time it acts up again, make sure that the shifter is on P or N, then try to jump start on the junction box located on the passenger side, so you can rule out the NSS

Biodiesel300TD · #7 02-23-2010, 11:02 PM

The neutral safety switch prevents you from starting the car unless the gear selector is in neutral or park. So make sure it's in one of those two if/when it happens again. If it's the shifter bushings you'll have a hard time getting the car to go into gear. Bushings are really easy. They are just rubber grommets that you have to squeeze in. Basic tools are needed, but nothing fancy. If it's the neutral safety switch it might work and not work for a while, but eventually it will stop working all together and you won't be able to start the car. It's a DIY job too. Don't let the dealer do it. Everyone here can help. And you'll save a ton of money. I'd highly suggest you learn to do some basic stuff with you car. Owning any 25 year old car can get expensive if you have to take it to the shop every time something breaks. Take on the little things, and before you know it, you'll know the car like the back of your hand.

charmalu · #8 02-24-2010, 03:38 AM

The Junction box listed above saved my rear a couple times. It is a black box 2 in X 1in, near the battery on the inner fender. has some wires going into it. pull up on the cover to expose the 3 screws.

parking brake on, shifter in park, key turned to glow position. now short across from the large screw to one of the smaller screws, and the engine will start. I use a pair of needle nose pliers for this.

Charlie

amosfella · #9 02-24-2010, 03:57 AM

Quote:

Originally Posted by charmalu

The Junction box listed above saved my rear a couple times. It is a black box 2 in X 1in, near the battery on the inner fender. has some wires going into it. pull up on the cover to expose the 3 screws.

parking brake on, shifter in park, key turned to glow position. now short across from the large screw to one of the smaller screws, and the engine will start. I use a pair of needle nose pliers for this.

Charlie

It can be fun taking the starter off after you've done that a few times.... I'm using the word 'fun' sarcastically....

byronnash · #10 02-24-2010, 07:19 AM

That's good to know that both of those are easy to fix. I do plan on learning how to do as much as I can myself. I can't afford to get work done at the dealer.

fruitcakesa · #11 02-24-2010, 08:34 AM

The NSS is a simple repair. On my 240 it is mounted on the driver side of the trans.
It also controls the back up lights.

charmalu · #12 02-24-2010, 12:23 PM

Quote:

Originally Posted by amosfella

It can be fun taking the starter off after you've done that a few times.... I'm using the word 'fun' sarcastically....

What does that have to do with the starter removal?

I didn`t say to do this on a daily basis. I had my NSS act up when I was 300 miles from home in front of my Parents house. they are Ford people, and don`t have warm fuzzy feelings for our MB. I just casually opened the hood and kicked it over and shut the hood before they came out. only time it did it that weekend. changed it when I got home.

It is a good back up when a start problem arises.

Charlie

kerry · #13 02-24-2010, 12:29 PM

You can also jump the NSS at a junction in the wiring above the drivers kick panel if you don't want to mess with the NSS. Instructions in a thread here somewhere. I think they say the wires are purple or violet and are above the accelerator.