A Dalton, Hope you're still willing to help.
I installed new battery and pulled the instrument cluster when the tools arrived today. (not as hard as I thought). I pulled free the round connector with 15 wires behind the fuel gage. I am assuming this is the k38. The pins are arranged in a circle. I jumped 1 & 3 (on the harness connector not on the pins protruding from the cluster). No start. I checked for voltage on both positions in the crank position and got zero. any help appreciated.

You just pull the relay. It should be towards the upper/left of the dash opening. [ behind the gas gauge location] There may be some insulation in front of it.

Look for a small , regular looking relay. Pull it and jumper 30 and 87 ..plug it back in and try to start the car.............................

Thanks. I will get on it first thing in the morning.

Found the relay just where you described.
soldered across 30 and 87 and plugged in.
on crank position the horn blows steady but no start.

Make sure the alarm is not armed
All doors closed and hood closed.

Is horn steady, or is it repeating on/off ...like alarm mode?

horn is steady.
If I turn to crank horn on. if i turn back one click horn off and if back to crank horn on...
I will go down and try it with all doors closed and make sure alarm is deactivated by door locks but I don't think it is the alarm since it's just steady in crank position. The relay is clearly labeled and I know i jumped the correct positions. I also double checked the x49 in case I did not confirm good ground on previous attempts and got no voltage at 3 or 4 in crank position. I do have a spare parts car and could grab the relay out of it if this relay is suspect. I will post again in a few minutes after repeating the k38 test.

Looking at your schematic, I think you have mistakenly jumpered 30 and 87a.

Check that your jumper is to 87 , NOT 87a.
87a is Armed mode and will blow Horn.

will double check that too and be right back

I did publish a photo of the relay here
http://web.mac.com/fulltimefamily/iWeb/Site/Photos.html
mine has three pins label 86, 87 & 3 (no 87a)

Are you telling me that relay has only 3 pins??

That's right 3 pins and no other relay visible.
Did double check arm and disarm and try with all doors close with same horn result.

You must mean 86, 87, and 30 ???

Take the relay out and jumper right at the plug the relay plugs into.

That should be marked #1 [ for relays 87 pin] and # 3 [ for relays 30 pin]

That will/should be the V/GN and V wires at that plug.


Don't go doing other stuff on me...

roger that.
I will only do as directed.
Just to described what I had done. I soldered across the pins 3 & 87 on the relay.
I will remove the solder and try to jump the connection. I am having a hard time seeing into the recess to see labels or wire colors (not much room) I did not fully disconnect the cluster but pulled it out and to the side. I will be back shortly

< I soldered across the pins 3 & 87 on the relay>

Are you going to answer my other question??

I ask again...did you mean 30 , not 3???????
There should be no 3 ..there should be a 30 .
Verify

Yes, so sorry. it's 30 not 3

Sorry for the delay (it's raining and I'm working outside on this)
the plug is labeled 1,3 and 4. 1 goes to 87 and 3 goes to 30. Give me just a minute to jump the 1 and 3.
Looks like three wires are going to the plug. I think all wires have a black stripe. colors are violet, brown and white with red spots.

Started right up (when I finally did as instructed)
Thank you so much AD. Please tell me how to make this permanent. I don't understand why soldering across the relay pins did not produce the same result.

Ok

The suspect problem is the relay contacts have shorted to 86 , which will then feed the ATA and blow the horn. [ relay probably rattles??]
Anyway, What I would do is to take the top of the K38 relay and junk the coil and contacts internals, just leaving the pins and the base..then solder a jumper across 30 and 87 and plug the relay back in as your permanent jumper . Make sure nothing else is left on these pins, please!!!!
If anyone ever works on the car starter circuit again, just tell the Tech yours has been rewired to Canadian Version [ No K38 circuit]

We did a post on the best way for you to get an answer from this Forum a couple of years ago, and you may want to go read my post [ post #2]
at the top of the page:

http://www.peachparts.com/shopforum/tech-help/127343-troubleshooting-get-most-your-post.html

That post info about sums it up and sure does fit this one.



Seeya.

Thanks AD.. I read your post on posting and I hope I did due diligence in searching the forum before asking for help. In spite of my confusion and questions you patiently got me through this job and I have a great deal of satisfaction from being the hands if not the brains on fixing this. Very best regards.
Ray

Very Good.

You get a C- , but I am sure the next time around will be cool...
This one was testy, so I am giving myself an A+ for Patience.

Glad it's over.

Success Story:
I took the cover off the relay and inspected the coil. Of course everything of the electromag contact in the relay seemed to be ok and no sign of short. I figured it might have been stuck before I opened it so I went back to the car but before plugging it in I removed the jumper and just for fun I tried cranking before plugging in the relay and it started right up with no jumper and no relay. I plugged the relay back in and it starts then too. The horn works fine.
The only remaining glitch is it will not start in neutral; only park. I'm delighted and posting this info for whatever it may be worth.

If it cranks with no jumper or relay, then someone has already jumpered the K38 circuit out and you have a bad NSS.
That is why , way back in your early post, you had a V wire from ignition sw down at the NSS x49 plug when it was supposed to be V/Grn..
Remember that?
That would indicate K38 has already been bypassed.

91 560 SEL- no start, and no cranck
 

Arthur:

I am getting the same symptoms as fulltimefamily ( no crank, no start, batt is 12.4V). It started fine one morning ( 2 days ago), turned off engine and parked it for about 10 minutes. tried to start it thereafter, and no crank. Are the steps in here applicable to a 91 560SEL?

thx

Did you try "N " gear selection??

Arthur:
Thx for the quick reply. Neutral does not work either. I found my schematic and for my car and as I see it, the flow is in this order:
1. ignition sw (S2/1)
2. Starter Lockout/backup lamp switch(S16/1)
3. Starter harness connector (X27)
4. Starter (M1)

I jumped the Batt+ to X27(pin 2, male end) and I could see spark at the Batt+ terminal as I try and jump but could not get the starter to turn. So I concluded I have a bad starter. One thing that confused me though was that in this thread, you had mentioned that it is the "Mounted to firewall" end of the X27 plug that needs to be jumped. I found that for my car, it was the opposite. I traced the continuity of the X27 harness, and found that the "unplugged end(male) that is NOT mounted to the firewall" that actually goes to the starter solenoid. I have ordered the starter and hope to get it in by Thursday. can you confirm if I am on the right track?

The firewall thread was for a later model with dual firewalls..

..but , now that you have jumper to x27, you have to test battery voltage..if low, then the starter solonoid will not pull in. The x27 test is from x27 downstream to starter , but it does not test the starter circuit for low V, it test power to x27.
Don't assume the starter bad until you verify Bat V
An easy test is to put the headlamps ON and watch that they do not dim out when you jumper to x27..if YES, then you have low voltage and should charge the battery before buying a starter [ and check the connections at starter, specially the main cable..

You can also put a test lamp on x27 and try the key to verify upstream.....you can see that on the schematic.
X27 is a comvienent test point we use to seperate a fault from the cabin or the engine compartment..you then know upstream/downstream circuit fault direction/isolation..a good central test point in the start circuit.

good point. Here are some observations that I have:
1. Batt voltage at NO load is 12.4V
2. When ignition is at "Start" position and X27 connected, dash warning lights dims and stays dim even after ignition switch returns to "RUN" position. It takes a while before dash warning lights return to normal illumination. Starter does not spin.
3. The same is observed when X27 is disconnected. It looks like other components are drawing current via X26 even if the starter is disconnected at X27. Does this symptom suggest another possible problem?

I think it may help diagnose the batt if I measure the voltage ( with load) accross the batt term when doing #2 and #3. what do you think?

I think you have low voltage battery..[ or bad starter]
Charge it overnight ..or , simply jumper the car with another known good battery and see if starter kicks in.
You are almost there........and you did good reading the schematic series chain..

I would also take a battery jumper cable set and just use the neg cable...hook one end to bat neg and the other to engine ground..that will eliminate any possible Bad Grounds.
If that works, then look at all ground cables [ brown ones ] and the one going from the trans bellhousing to chassis ..the flex one.

A last possible is the starter brushes are so far worn that the starter is drawing high amps and just won't turn b/c of the wear..you will know that when you jumper from a good battery. Sometimes a good smack on the started will get the worn brush to seat, but it will be temporary and will definately need a starter........just don't want you to buy one until you know you need one.............

you are correct. it was a bad battery. I had to call a roadside assistance as i wanted to get the car out of the driveway so I can get my second car out of the garage,a 66 mustang conv. The tow guy thought at first too that it was a starter problem, but I asked him to try and jump it anyway. 3 tries on the ignition switch and it started up. I took the battery to Kragen where I originally bought it, and it tested bad. It is an autolite. I got 50% off for warranty. Thank you for the pointers. very helpful indeed. I have another problem that I will start a new thread. I have been having this hard start problem after I rebuild the engine. I will soon have some time to focus on it. hopefully you will be available to help....

Very Good.................

i'm hoping to get a little help with my e320. excuse me if i'm interupting a thread if i am. i'm new here.

94 e320: alarm will not disengage so i'm unable to start the car. the car was left out with the top down recently during an unexpected rain. i figure that may have something to do with the problem.

any help would be appreciated.

Thank You
 

I just wanted to take the time to say thank you Dalton. I experienced a no start/no crank situation with my 1995 mercedes E320 wagon, and I spent quite a bit of time trying to track down diagnostic information & wiring diagrams without much luck. I found a few posts that referenced a few things here or there, but none of them took the time to describe the circuit in detail. Your posts made the entire process perfectly clear. I now understand the path of the circuit from the battery all the way to the starter; the location and appearance of the ignition, K38, X49, K27, and starter sections of the circuit; how to properly jumper these locations if it is necessary to bypass them; and the really handy K27 "emergency" start trick. With your post I can finally diagnose & fix my car...that is once it stops being a pain in the butt by deciding to work again. I know that it will break again sometime soon, and until I can afford a new digital multimeter I don't have the ability to test beyond On/Off with my test light. I also wanted to tell you...not sure how to put this, but you have great patience with dealing with others. I know that electronics can be a pain to deal with, but it definitely helps to follow the procedure...and the path of the circuit...and I suppose to understand basic circuitry. Thank you again very much!

Problem With Alarm
 

Most of what you need to fix this problem is probably contained in these posts. I would start by disconnecting and reconnecting the battery. Then I would check fuses 5, 11, 12, 13, and B with a multimeter or test light. Be sure to test at the connectors as opposed to the fuse itself, so you can be sure that not only is the fuse good but that it also is getting a good connection. Hopefully, the solution to your problem will be found somewhere in there. Otherwise, you may have a problem with the actual ATA unit itself. I believe there is a way to bypass it, but I'm not 100% on that. You could also obviously replace it if it is bad, but that's a choice you have to make based on how much money you're willing to spend for a given level of functionality. Since this post was made back in 2008 I'm going to assume that you no longer need this response, but maybe someone else will. I find that usually disconnecting the battery resets the alarm.

**Edit**

I'm pretty sure that the fix for bypassing the ATA is simply jumpering the K38 relay. You can find the correct pins and wire colors earlier in this thread.

You're Welcome .

A Dalton
BenzTechs

Just wanted to add that the description for fuse 5 does indeed tell you that it's for a bunch of random things unrelated to the starter circuit, but they LIE! It is definitely a key point in the starter circuit despite what they say on the little card on the fuse panel

I can also verify that on mine I have the same colors for the wires

What would you suggest for jumpering these terminals? A piece of 18 or 20 gauge wire or something like that bent in a U shape? If I didn't happen to have any wire lying around do you think an upholstery staple bent in half would work? I know it sounds kind of...well...iffy, but I can't really think of a reason why it shouldn't work off the top of my head. What do you think?

I'm just going to go ahead and slap myself for suggesting using a staple. I mean I suppose it could work in an emergency, but then again in an emergency you might as well just jumper the X27 connector to the + terminal. I discovered that anything under a foot of wire at HD is free, and I needed to pick up some solder, flux, and a few other things for another project anyways. I got about a foot of wire that contained 5 strands of 20 gauge solid core insulated wire. I pulled the outer sheath off; stripped the insulation off one of the wires; wrapped it in a figure 8 pattern around the 2 prongs; and then finished it up with a bit of solder just to ensure a solid permanent connection & to help keep it in place. Congratulations to me for finally getting a hand on soldering. I don't know why, but I've always been HORRIBLE at soldering anything. For probably the first year of soldering my technique involved touching the tip to the solder, and dripping it onto what I was soldering. In case you don't know...that is NOT how you solder, and that will create what we call a cold soldered joint which is extremely weak. Nobody told me, and back then we didn't have youtube and stuff like that for me to learn from easily. Again, in case you don't know... the proper way to solder something is to touch the tip to what you are soldering until it gets hot enough to melt the solder. You need the wire or post or whatever you are soldering to heat up to the same temperature as the solder in order to create a strong joint. I guess back then that I thought this would damage what I was working on or something like that. I don't know, maybe I just thought it was easier. Anyways, I put the modified relay into the car, and it cranks and starts strongly each and every time. Oh, and for the record it is the silver relay not the blue one...at least in my 1995 w124 wagon. It's the one furthest to the left. I believe the other one has to do with the dash itself because when I jumpered that one earlier I blew fuse 5 and my tach went out. Replacing fuse 5 brought my tach back.

What a great troubleshooting thread here! I have had low battery issues which cause no start..and also the immobilizer relay up behind the gas guage failing...I would need to bank on the dash on the left side and then it would click and start right up and I just replaced the relay for $20 including shipping and its dead reliable now..

These cars work so great when the issue is identified and resolved but are so complex as to be confusing if you are missing a little information..AD and Rick 76 and others are a wealth of assistance and hopefully we can pass on the good information..(94 and 95 E320)