'83 300SD won't turnover - PeachParts Mercedes-Benz Forum

rcwarship · #1 05-04-2011, 12:19 AM

Hi All,
I'm stuck & was wondering if I could get some help.

1. Instrument/glow lights come on
2. Key is turned, no cranking
3. Key is turned, no cranking in both Park & Neutral
4. Bypassing starting circuit by connecting starter directly to battery = cranking
5. Connecting solenoid wiring connector (small one) to battery = cranking
6. I've checked the fuses in the fuse box with a meter, all are good
7. The following listed article suggests checking the fuse in the C105 connector http://autorepair.about.com/library/faqs/bl158i.htm - I don't have one on my car.

Questions:
1. Any ideas if there is a fuse/connectors between the regular fuse box & the starter/solenoid? Or is it just a straight run?

2. Is there a connection between the glow plug circuit & the solenoid?

3. Any other ideas?

Thanks & Best Regards,
Jon

kerry · #2 05-04-2011, 12:36 AM

Sounds like a bad neutral safety switch. You should be able to start it by jumping the terminals in the plastic covered junction box on the right inner front fender near the alternator. Not sure which terminals to jump--could be the first and last.

rhodes2010 · #3 05-04-2011, 01:32 AM

The ignition switch at the back of your key assembly can also cause this.

Two ways: the switch can come loose from the back (three screws)
and the other way is the switch itself.

I have had to rebuild one once. Took it apart, cleaned it, put it back.
Then had one that was loose. Tightened it up and it worked.

The really good news is that your tests prove it is good battery and starter.
No - there is no ither fuse in the link to look for.
Pretty much fusebox.

And there is always the possibility of the neutral safety switch.
There must be an easy way to jump over that and test.
One not so realiable way is to move the shifter through the range with the key turned.

That block in the passenger (right side) fender well is a great place to jump
the car with some insulated pliers. Taught my neighbor that one for emergencies.

kerry · #4 05-04-2011, 08:39 AM

There are instructions somewhere on the forum explaining how to jump the NSS wiring behind the driver's kick panel. I think it involves jumping across the two violet wires which feed the NSS.

rcwarship · #5 05-04-2011, 07:51 PM

Thanks guys, I just got through bypassing the key/neutral safety switch at the black junction box near the alternator & she starts/runs.
Since it's easy to get to & I don't have time this week to get into the neutral safety switch, I'll be working on it this weekend. In the meantime, I can get it started on demand & am back in business.
I replaced the key/ignition assembly about 6 months ago & will recheck connections there......I tried gently tugging on the connector & it was tight, so it's looking like the NSS failed in the open position.
Hmmmmmm during my test drive, the speedometer no longer functions, maybe the 2 are related.
Thanks Again & Best Regards,
Jon

Stretch · #6 05-05-2011, 02:56 AM

This came up quite recently in this thread:-

http://www.peachparts.com/shopforum/diesel-discussion/298080-stuck-storm-comming-how-directly-jump-starter-post2708674.html#post2708674

Read the warnings at the end of the thread too!

tiger64 · #7 05-05-2011, 01:59 PM

I have 85 SD. Had similar situation. Weird because it happened in the cold weather in the morning most often. I waited a year to see if something really failed. It was fixed completely with a new starter. Specifically it was the solenoid. You might just replace the cable and clean connections, but it is the starter. When you by-passed you might have just changed the connection or the amps enough to bump the solenoid

Diesel911 · #8 05-05-2011, 02:56 PM

Quote:

Originally Posted by kerry

There are instructions somewhere on the forum explaining how to jump the NSS wiring behind the driver's kick panel. I think it involves jumping across the two violet wires which feed the NSS.

The instructios are for and 84 300D.
http://www.mbworld.org/forums/diesel-forum/313982-no-crank-1984-300d.html
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.”

Also I believe he does have a terminal block but it is not in the same place as a 300D.
But, since he already knows what Wires go were He knows how to crank the Engine.
If the Neutral Safety Swich on he year and model uses the same colored Wires he could bypass the NSS down by the Switch itself (there should be another connector there).

rcwarship · #9 05-22-2011, 05:57 PM

kerry, rhodes2010, army, tiger64, & Diesel911
Thank you all very much for your help. With your kind assistance, I was able to get the engine going until I could make a permanent fix.

The symptoms:
No cranking, glow plugs & normal lights on dash, however no engine cranking when the key was turned.

The problem:
The connector that is near the gas pedal had worked it's way loose.

The temporary solution:
Start the engine with a jumper to bypass the NSS (Neutral Safety Switch) until the weekend rolled around.

The process:
Turn the key to "Run", ENSURE THE TRANSMISSION IS IN PARK, open the hood, grab the jumper & temporarily place it across the connectors to crank the engine. After the engine starts, close the hood.

The connector was located in the lower passenger side of the engine compartment:

The permanent fix was to push the connector back in place tightly:

Thanks Again & Best Regards To All,
Jon