94 e320 won't start...weird problem

[skiier3_9]

This is the second time this has happened to me now. I go to start my car and I get all the electronics/power/etc. but when i turn the key to start nothing happens. The first time this happened I had to have the car towed to a local shop where they claim to have "reset the security system". The car then started fine for a week (I would estimate 15 or more starts) and then today the same situation happened. I haven't had the car towed or anything since its at my house. I was hoping that someone here could help me diagnose the problem.

I have tried:
1. disconnecting the battery for xx minutes
2. lock/unlock from all locations
3. start the car in N and P
4. kick the tires....

BTW: When i turn the key to the run position, I can hear the fuel pumps come on (slight buzzing/hissing sound)

Is it possible to "reset the security system" as the local mechanic tells me or are they lying to me.

Please help, this is SO frustrating, I don't even have 1000 miles on the car since i bought it and I've had multiple problems. TIA

[71Rcode]

Skiier - do a search for one of my old posts - about six months ago. Or, do a 'title' search for E320 / start / or something like that. I had the SAME problem with my '95 model. Ended up having to replace the starter - lots of good troubleshooting hints in that post. Good luck. 71Rcode

[mbdoc]

The 1993-95 E-class have a starter interlock relay behind the instrument cluster. The alarm control unit must send a signal to that relay to allow the starter to operate. Best fix is to by-pass that relay!

[skiier3_9]

Originally Posted by 71Rcode

Skiier - do a search for one of my old posts - about six months ago. Or, do a 'title' search for E320 / start / or something like that. I had the SAME problem with my '95 model. Ended up having to replace the starter - lots of good troubleshooting hints in that post. Good luck. 71Rcode

I found your post - did you have any indidcation that the starter was going bad? Or did it just die.

MBDoc - Is it relatively easy to bypass this interlock? I'll do a search to see how to remove the insturment cluster. Thanks for the info.

After searching the forum last night it sounds like this could also be a neutral safety switch problem. Is there any way to test or eliminate this from the list of possible causes?

[mbdoc]

The neutral/park switch would show-up as the problem IF the car wouldn't start in one or the other position.

After removing the cluster simply solder(OR have it done) a wire on the inter-lock relay between terminals 30 & 87 and plug the relay back in.

Doesn't sound like the starter BUT you won't know for sure until the relay has been defeated.

[skiier3_9]

thanks for the info on the relay, i'll give that a shot before i throw any money at the car.

[skiier3_9]

M.B.Doc: per your advice I shorted pins 30 and 87 on the K38 relay (starter interlock) and the car started up just fine (well sort of...see my other post about the BRAKE light/buzzing here ).

Now, what is the name of this relay on fastlane? I can't seem to find it. Hopefully replacing the relay will solve my problem for good.

Edit2: is the p/n: P2020-25016 under Relays... i found this one that looks exactly like the K38 (and has the same pin numbers). Is there any difference between the hella and the silver (OEM looking) one?

Thanks guys for all your help!

Edit (more problems): The P.O. had done some work behind the cluster before as the ABS (or SRS I'm not recalling right now) had an extra wire coming from the circular plug on the opposite side of the insturment cluster. This wire was eletrical taped on at both ends. So>> after shorting the relay, testing the start, and then plugging everything back into the insturment cluster none of the guages work properly. The tach jumps at start up and promptly falls back to 0, oil pressure hovers just off the needle and fuel + temp have no response (although i didn't drive the car so dunno about the temp function). The lights still come on with the headlamps if that means anything.

[kramlavud]

I had the same problem a few months back; and Arthur Dalton showed me how to test the neutral safety swithc from the emgine compartment. Open the link following this paragraph, and scroll to the 4th post on the 2nd page. My engine started when I applied battery voltage to the switch as directed by Arthur, thus my NSS was at fault. Had a new one installed and the problem was solved.

E320 won't start

regards,
Mark

[skiier3_9]

I recieved my new K38 (starter interlock) relay today, plugged it in and still the car does not start.

I tried reseting the security system (lock/unlock drivers door and trunk)

So, any ideas? Troubleshoot the NSS now? I thought i read about a NSS relay under the dash somewhere. Also, how can I test the NSS?

Thanks everyone.

[kramlavud]

Did you perform the NSS test from my post above?
Mark

[skiier3_9]

I'm not sure how to complete the test you indicated. I'm sorry, I just need a better description of the location of the indicated parts:

Originally Posted by kramlavud
Arthur,
I tried P and N positions several times yesterday and today, also moving the shift lever side to side in N as you suggest, with no improvement.

OK you do not move the shifter side to side , you move it foward and rearward of it's normal gate position...and while holding the key in start position without releasing the key during this test..but I do not think that is the problem.

I assume the click I hear is the starter solenoid. The click comes from the engine compartment. Maybe I did not test with the lamp correctly. I connected the red alligator clip to the engine lifting ring, pushed the probe through the purple/white insulation, turned the key to start, and the light did not illuminate.

OK . I want to make sure you are the right connector/plug.. it is a 3 prong , all in a row connector held to the wall with 2 screws .the V/WT is the center connector...... maybe your light is out or you had not pierced the wire fully... test your light by leaving the red on the ring and go to the bat + to test lights integrity..

Here is another prof positive test that will test the same point , but in a different way..
Get a jumper wire and hook one end to the bat + ...
Now, unplug the connector at booster and I want you to look at the 3 MALE connectors at the part of the connector that is screwed to the wall..[not the part you unplugged w/ female connectors]
Take your bat + wire and touch the CENTER MALE connector .. the starter should crank the engine ..if not , you have a problem at the starter or wire going from this connector to the starter.. if the starter turns the engine over [ cranks] w/test, the starter/sol are verified as GOOD. This means you are not getting power at the wall 3 prong connector and the problem is in the NSS circuit..
The reason for testing at this point/connector is that it is a place in the circuit that is easily accessed and it is the dividing point [ electrically] between the NSS circuit and the starter/sol circuit
I think you follow me....


I got under the car and believe the locking ring on the NSS connection is OK. It is in the 'down' position. If I push it 'up' I can wiggle the connection, but in the down position, the connection is tight.

regards,
Mark

where are these connectors?

Heres a picture that I have off my ALLDATA CD's: attached

edit: would the X42/18 or the X49/1 (pictured) be the correct connector to try this trick suggested by Arthur Dalton:

Originally Posted by Arthur Dalton

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..

[kramlavud]

This is the method that proved my NSS was defective:

"Here is another prof positive test that will test the same point , but in a different way..
Get a jumper wire and hook one end to the bat + ...
Now, unplug the connector at booster and I want you to look at the 3 MALE connectors at the part of the connector that is screwed to the wall..[not the part you unplugged w/ female connectors]
Take your bat + wire and touch the CENTER MALE connector .. the starter should crank the engine ..if not , you have a problem at the starter or wire going from this connector to the starter.. if the starter turns the engine over [ cranks] w/test, the starter/sol are verified as GOOD. This means you are not getting power at the wall 3 prong connector and the problem is in the NSS circuit.."

The connection in Mr Dalton's directions is near the brake master cylinder but located on the 'wall' between the engine and the master cylinder and vacuum booster. Disconnect the plug and apply the battery's voltage to the cnter male pin; a really easy test (you may have to put the ignition and turn to "run", I don't remember).

regards,
Mark

[Arthur Dalton]

<<(you may have to put the ignition and turn to "run", I don't remember).

>>

Not needed ... the test is a direct connection of bat power to starter solinoid.
This is a diagnostic trick to eliminate the starter/sol. circuit before getting into the chain of starter circuit power of NSS and ATA systems..
[ starter/sol. verification, if you will - just a good place to start diagnosis due to the ease of the connector location.. ]

[skiier3_9]

So, if the starter engages when I apply power to this lead I need to test the NSS (since i replace the K38 relay). Where is the NSS switch connector? Is it in the picture that I attached above?

Thanks again!

[skiier3_9]

Alright, I just testeed the starter motor by the method described, it engages immediately when power is applied to the middle male connector. I guess that pretty much leaves me with the NSS.

Q: When I shorted pins 30 and 87 on the K38 (starter alarm relay behind the instrument cluster) it appears that I also bypassed the NSS according to the ignition schematic that I have attached. Is this correct? If so, it pretty much points to the NSS being the only thing left to be bad.

Q2: Is it "ok" or safe to drive around with the pins on the K38 relay shorted? The e320 is my only transportation and the city bus/cabs are getting awfully annoying.

Thanks again! I'm sure I'll have more questions about the install of the NSS if that ends up being the problem.