Got 'the dreaded' call from my wife this morning, while I was at work. She was going to take our baby to the doctor, but her '95 E320 (cold engine) wouldn't start. Never an issue before (90k) - never a sign of a no start. I had her try and start the car in neutral, and in park moving the shifter lever all around. No luck.

Got home and got the car up a bit so I could check out the neutral safety switch. I was able to fiddle around with the "white, moveable" ring that fits against the outside of the switch (I believe the ring moves with each gear selected). Anyway, after a crawling under the car and back up - fiddling with that ring - it started. Went through all the gears (idling in the garage), put it in park, and tried the ignition again. No start. Again, fiddled around quite a bit (maybe 30 minutes worth) and got it to start. I immediately shut off the engine, crawled back under and took a mental note of where I adjusted that 'moveable ring'. Got back in the car - started again. And again. Then, nothing.

So I pulled the switch - and cleaned the contacts. Didn't have to pull it to clean them, really. But I wanted to evaluate it, to see if it was serviceable. Cleaned the contacts and put the switch back on (10mm - two bolts) with no luck. No adjusting this time would work.

------------

So - I think all I need is a new neutral safety switch. What do you guys think? Battery is charged. Cold engine. All fuses are good. Hear fuel pumps charging. Hear power getting to solenoid (at times). I think it has to be the switch, as I was able to fiddle with it and get a start.

Is the neutral safety switch all I should order? There is a round sensor (male, two connectors) that sits behind the neutral safety switch. The plug 'threads on' like a water spicket/hose. What is this guy? Looks tied in somehow.

Many thanks guys. I do appreciate it! Best regards, 71Rcode

How about the OVP?

Is it the original unit? If so, replace it.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

That certainly sounds like the problem. A neutral safety switch is only $52 at Fastlane, maybe a hundred at the dealer. That sounds like the way to go if you're looking to have a reliable car. If the shifter bushings are suspect you might as well do those as well while you're there. There's two bushings at about $2 each. They're tricky but there's plenty of info in the archives on putting them in.

Thanks guys - I do hope it's as simple as a total failure of the neutral safety switch.

Paul, I checked the OVP yesterday (fuse on top was fine) - that was the first thing I checked. This morning I went out and pulled it, no rattles, and the connectors all looked fine. Plugged it back in. No start. Then I checked the position of my neutral safety switch - put the car in reverse and got backup lights. Not that it means anything, but I wanted to make sure the switch was in the right spot.

Would you mind e-mailing me today at work? I could use your help troubleshooting. Down a car is tough for us.

The white ring you refer to is just a plug retainer and has nothing to do with adjustment.

First, the most common problem is worn shift rod bushings. Check and replace, if needed.

If you noticed, the two holes in the switch that the mounting bolts go through are elongated for adjustment. Assuming the bushings are OK, with the selector in neutral on the shifter and the (metal) lever on the trans also in the neutral position, the switch needs to be adjusted by rotatiing at the slots to align the little black plastic rod on the switch to the metal arm with a pin through both into a hole in the trans body. Then tighten the two mounting bolts.

If all of the above are correct, it is either a wire problem or the switch itself. Both can be checked with a meter.

Thanks for that clarification. Last night, it seemed the white ring was for some other purpose, as it has detents and tabs on it, and it spun. That makes me think (today) that my 'adjustments' last night to the neutral safety swith - that resulted in a start - were possibly a coincidence. My shift rod bushings are both there - and looked good. But I have new ones on order as I type this. Yes, I noticed the elongated holes in the switch - and did attempt to adjust it with no success. I do appreciate your steps on aligning it (the proper way).

Also have a switch on order, and will replace what I think is the bad unit. Just from having switches go bad in my 940s, there usually seemed to be a warning sign or some kind. As in intermittent no starts. Our MB just gave up starting yesterday. No signs of a failing switch.

Tell me, how should I check the switch with my meter? And when you say a wire problem, what are you referring to? Again, thanks for the great advice.

There are 4 pins on the switch where the plug goes. 2 are to the contacts for P & N and 2 are for R to complete the circuits (start & backup lights). You should see continuity across the right pairs if the switch is OK. Otherwise it could get to be a pain should there be a problem in the wiring somewhere.

My old switch had oil, dirt, etc. in it, which likely prevented the contact (P &N) from making. Now the mystery is that the backup lights don't work with the new switch!! They were fine before.

Nowhere in your post do I see you mention if the engine CRANKS .. Does it??
You mention it does not start, but "Start" to a tech can mean the car does in fact crank [ starter motor attemps to start car], but engine will not start
[ RUN]..
I mention this cuz E320 are famous for not starting due to a bad OVP.. but with a Bad OVP, the car will still CRANK.. but not START..
..if it does not crank, forget the OVP, as it has nothing to do with the starter circuit.
If the car does NOT crank, you are on the right track with the N switch. But if it won't start, but cranks , this is NOT the problem..
Anyway , the N switch white ring that you are turning is only the lock tab for the plug [ so it does not fall out..it is a retainer ring]
The terminals at the switch that should have continuity when the shifter is in N or P are #3 and#4 ..these are v/wt and v/grn wires . This is where an ohm-meter can be used to check for a connection/points contact. One may also just jumper these two and see if starter turns engine over w/key..that would indicate bad sw.
This cable also runs into the car, under the steering wheel/dash and can be jumpered there for testing.[ 4 prong plug. same #s]
The other 2 terminals are for back-up lamp..terminals # 1/2..

Et al.
The reason I mention the crank/start difference for posters is cuz the diagnosis of a starter circuit and a running circuit are so far in different directions that the first question you are going to get back from a Tech is
" Do you mean it just turns over and won't catch or do you mean it just does NOTHING? " ..from there , it is easy...

Joe - great info. Thanks for that. I'll test it. Hey, I'd trade you b-up lamps for a consistant start - any day of the week.

Arthur - I didn't make that clear, did I.... It WON'T CRANK. Fuel pumps cycle, and sometimes I get a 'solenoid' like click, and other times not. However, fiddling with the neutral safety switch allowed me TO START and RUN the car a few times last night. But I coudn't ever get a consistent result. And my b-up lamps are working great.

Thanks for clarifying Joe's post. I appreciate that. I would've jumpered two of these leads together, but I wasn't sure which two. I'll look for it to where the harness runs under the steering wheel.

Yes - the problem is in the starter circuit. NOT in the running circuit. And yes, turn the key - and I get NOTHING. And "it is easy" is in the eye of the beholder...lol. Thanks again for your help, guys.

Cool.
All conditions points to a bad starter lock-out sw. then..

The "Easy " part was in reference to the Techs job of repairing the problem being sometimes easier than getting the proper info to do so...

Arthur - very cool of you to stick with me on this one. And the rest of you guys. Be watching for my reply - if I can get a chance tomorrow night, I'm going to replace the switch (and then pull the battery to find that nut that secures the OVP

Thanks again, man! Best regards, 71Rcode

Been there / Done That with the OVP nut..
Don't forget to make sure you have your radio code before you disconnect bat. power .....

..also, while 90% of the time a bad Starter Lock-Out sw [ that's German for NSS] solves the problem, be aware that both a worn ignition switch and a bad starter holding coil [ solinoid] ] will display the same conditions..
so. we will follow this to the end, just in case ..

Very good. I suspected it might be an ignition switch as well - and why I thought for around $30, I'd order one from Phil at Fastlane. It will be here today with my NSS. Thanks Arthur.

Arthur - NO LUCK - No crank. I replaced the neutral safety switch - it's all aligned - and nothing. Same thing as before. She won't even bump the starter over. I also bought an OVP - didn't make a difference (knew I might need a spare someday).

In an effort to test the ignition switch, I wiggled the key around like mad when trying to start - and it made no difference. Also moved the gear selector switch around with the key turned all the way to the start position - and hear a 'hissing' only in Park and Neutral - I'm assuming this is the fuel pump. I do hear and electrical 'hissing' sort of sound if I leave the key in the 'run' position.

What do you think?? Trying to figure out how to jump the starter solenoid to get it to run, but it's tough getting to it on an E320. And there only seems to be the primary starter cable (large wire that's not exposed that attaches to the front of the solenoid) and what looks to be an exposed ground lug.

This is just I know I can get her started - and not have to get it flat-bedded to an indy shop...

Man - how dissapointing - as I was sure the NSS would fix it. Thanks for any advice you guys may have.

Turn headlamps on and then try to crank... watch if headlamps go out..if so, you have a bad connection on the bat or ground cable
If lights have no change , give the starter a rap and try again..

I will get the schematic out