Lately it seems members are haveing a spat of no Cranking problems with their starters.
I was over snooping at another forum and found this Info that I have never read before concerning how to bypass/test your Neutral Safety Switch.
This Info Concerns a 1984 300D.
Testing for no Cranking; explanation from 240D3.OT mbworld.org.
http://www.mbworld.org/forums/diesel-forum/313982-no-crank-1984-300d.html
“First make sure the selector is in P or N. Cycle through all the gear positions and try in N.
In front of the battery is a small rectangular box. Use a jumper wire to jump from one of the large posts to the small post with the purple wire. If it cranks, you've got an issue with the neutral safety switch or the ignition switch.
Above the accelerator pedal is a 4-wire plug with a harness that runs down to under the accelerator pedal and to the transmission tunnel. Unplug it, jumper across the two purple wires in the female plug and try to start again. If it starts, you need a NSS.”

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84 300D, 82 Volvo 244Gl Diesel

And, depending on which year of which model, you may also have a wiring harness problem. I had to completely rebuild the connector and a foot or so of wiring harness on my '96 E300D (W210, OM606NA). The "environmentally friendly" insulation had turned to hard plastic and fallen off of the wires.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Thanks, I will correct the above and ad the year and model. But, I cannot change the title.

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84 300D, 82 Volvo 244Gl Diesel

I had to start my 85 300D with that teminal a couple times when the NSS went south.

the plug above the accerator peddle has 4 wires. purple are the start.

I think the other 2 are black with a red stripe. those are the back up lights.

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Good piece of information there on jumping the NSS. Not all 123's have the terminal block in front of the battery to bypass the ignition switch. On 116's the terminal block is under the battery.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

The guy from the other forum used to post here also. His Avitar is VGT in a square.
What suprised me is that I did not read the info on this forum.

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84 300D, 82 Volvo 244Gl Diesel

this wont work on my 77 so thats why I make sure I have a good NSS

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

As this just helped me out and came up nearly first in my search for such a thing, I thought I would add to it. For my 81 300 SD this switch was found behind the carpet side panel next to the accelerator pedal, so you have to take that off to get to it. Also it is a 6 pin plug on the SD not a 4 pin but it is still two purple wires , which I had to take apart the plug to find out it is the top two ports.

Iam sure this terminal block could be added to the cars that did not come with them. I have pulled a couple off junkers at PNP. was thinking of putting one on the 240D.
In the picture below, the block has a cover, this one seem to be missing.

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

I went to leave for lunch, turned the key and no crank. I am pretty sure it is the neutral safety switch because of prior issues with it, but I need to start the car to get it home. I looked for the terminal by the battery to try starting it but I can't find it. Where is the terminal on the 87 300D? Or, where is the one with the two purple wires to bypass the NSS? Thanks!

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05 SL600 75K
87 MB 560SL 119K
87 MB 300D 180K
83 MB 240D 110K
64 1/2 Mustang
74 Monte Carlo 32K
75 Fiat 124 Spyder
16 Equinox
15 2500HD Silverado

Unfortunately this Thread does not apply to your model and year.

It would take looking at the wiring diagram for your year and model to find out where you could tap in to bypass the NSS.

In general if you want to crank the Engine on any Engien with an Electric Starter you will have to locate the Terminal on the starter Solenoid where the Wire coming from the Ignition Switch goes and connect that to a source of Positive Voltage. This is best done with a Remote Starter Button with Alligator Clips on it.

On some Gasoline Engined Cars you need to have the Ignition Switch ON when you crank the Starter this way or it causes some electrical problems (I do not know the exact details on that I just remember reading the warning years ago).

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84 300D, 82 Volvo 244Gl Diesel

Where is the starter terminal block for 87 MB 300sd? How do I bypass NSS?

I have been told this Wire Junction/Terminal Box is under the Battery Tray. This is where you can jump the Starter and get Starter to crank. Use proper precautions when doing that.

The other pic shows that the Electrical Connector on the W126 is close to the same location as it is on the W123. However, I don't know if the Wire Colors are the same.

Attached Thumbnails

   

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84 300D, 82 Volvo 244Gl Diesel

I found the terminal block in front of the battery in my 87 MB 300d. But when I tried to connect one of these terminals to the positive pole of the battery , nothing happened no crank(even I turned the ignition key on). The starter of 87 MB 300d may not connect to this terminal block like older MB(it worked for 85 MB 300TD and 80 MB 300D). Please help.

Someone with a W126 will have to chime in.

The old method when there is no nice Wire Terminal Block to use is to go from run a Jumper Wire or better a Remote Starter Switch from the Positive Battery Terminal (or another source like the Large Cable on the Starter) directly to the small terminal on the Starter Solenoid.

If that does not activate the Solenoid and crank the Starter your Solenoid is no good or there is not a good Ground.
If you hear the Starter Solenoid give a healthy loud click but the Starter does not crank you likely have some internal Starter issue line worn Brushes or the Contact inside of the Solenoid that connects the Voltage to the Starter is burned up.

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84 300D, 82 Volvo 244Gl Diesel