Mysterious fuse box

[66andBlue]

My early 280SL (VIN 05600) has a mysterious fuse box on the driver side next to the windshield washer pump.
Any cars out there with a fuse box at this location?
What is its function?
I do not have the fuse box for the radio hook up on the passenger side next to the regulator box and am wondering whether the PO used it for this function.

[49er]

That would be my guess Alfred. I guess an easy way to check is pull the fuse and see if the radio works. Also might just be for the power antenna if so equipped.

John

[twistedtree]

Mine powers one of the high beams.

[Jack Jones]

This fuse box is for the side marker lights.

[66andBlue]

John, Peter and Jack, thanks for the quick replies.
I can eliminate the side markers since those were not illuminated (they are now gone completely).
I have now traced the wires from the fuse back back to the headlight switch and it appears that the fuse served perhaps to protect the fog lights in the US-style headlights. Looking at the switch diagram in the technical manual the fuse wires are connected to pole 57 (which is normally not used) and to pole "N" where the grey/green/yellow wire from fuse #8 should have been connected. It was removed and taped back onto the harness. The 2 grey/green wires going to the fog lights are still connected to the other "N" pole.
What I do not understand is (a) why fuse #8 was bypassed and (b) how the pull switch should function when it is between "57" and "N" instead of between the "N" poles.
Peter can you help here? Or any other of the master electricians out there.

http://www.sl113.org/wiki/uploads/Electrical/Headlight_switch_wiring.jpg

[Peter van Es]

I (280 SL) also have one of those fuse boxes, with 2 fuses. One looks like it is connected through to the Constant Idle Solenoid... the other one looks like a lights function (side marker lights?) I did not have the time to follow the wiring.

Which of the wiring diagrams are you using to figure it out? This one?  http://www.sl113.org/wiki/uploads/Electrical/280slwiringdiagram.pdf

Peter

[66andBlue]

Peter,
I have used the one you linked and also the colored one in the Technical Manual.  It doesn't matter since the light switch is the same and the connections to and from it are basically the same.
After some discussions and looking at a mostly original late 250SL I have come up with some ideas about the peculiar wiring in my 280SL.
The standard wiring as shown in the wiring diagrams allows one to switch on the fog lights both in position 1 (parking lights on) and in position 2 (driving lights on) by pulling the switch as shown here:
http://www.sl113.org/wiki/uploads/Electrical/230SL_headlight_switch_postions.jpg

But as the instructions state "Fog lights should be used in accordance with regulation of individual countries" and in many US States (perhaps all?) driving with fog lights and driving lights (especially high beam) was illegal.
As can be gleaned from the switch diagram (below)  in position 1 and 2 contact is made with poles "58" (and "30") and that closes the circuit through fuse #8 to pole N via the grey/green/yellow wire. Pulling the switch turns on the fog lights.
When this wire from fuse #8 is replaced with a new wire connected to a fuse and then to pole #57 the circuit is completed only in position 1 but not in position 2 and the fog light can be turned on only with parking lights in position 1. That is the situation on my 280SL as described earlier.
On the 250SL the situation was different. Here the grey/green/yellow wire was also exchanged with a new wire as above but after the fuse the wire went to pole #56.  That pole is only contacted in position 2 and in this case the fog lights are turned on only together with the driving lights. Does that mean in some states you can use fog lights only together with driving lights?  
How the side markers come into play is beyond me, but perhaps it has to do with the elimination of the fog lights in later US-style headlamps, e.g.type AN and AJ. That would have freed up the extra fuse box to be used for illuminated side markers when those were introduced. 

[Peter van Es]

That sounds like an entirely plausible explanation. In some states, use fuse 8. In other states / countries use extra fuse. Choose which connection 57/58 on the switch to use to vary the behaviour.

In the Netherlands fog lights must be used with dimmed headlights. Using them with high beams makes little sense.

Peter

[mdsalemi]

I have this fuse box, too, Alfred.  I always called it the "Auxiliary Fuse Box".

I believe, or I was told that it is for: 1) Radio and 2) Power Antenna.

[66andBlue]

Michael,
the one I am referring to (look at the photo in my first post) is on the driver side in the engine bay. The one you have in mind for radio and antenna should be on the passenger side. If it is not then you should consider moving it to its proper location.

[mdsalemi]

Michael,
the one I am referring to (look at the photo in my first post) is on the driver side in the engine bay. The one you have in mind for radio and antenna should be on the passenger side. If it is not then you should consider moving it to its proper location.

Alfred, mine is in the same general location.  It is not attached to a set of plates/brackets like yours, but a single bracket, clearly from the factory.  See how it nicely fits the curve of the booster casting?  Looks like yours was added to a secondary "L" bracket. Also, my box (as I hope yours does too) has a cover on it, but was removed for the photo.  It is in the same place at it has been, right or wrong, since 1969.  

[66andBlue]

Michael,
wow,  clearly from the factory, that darn factory!  You should add the photo to all the other photos in this topic.  
http://www.sl113.org/forums/index.php?topic=13651.0
Never seen the bracket for the washer bottle been used like that.

However, if your fuse box is indeed used for radio and and antenna then it should be moved to the opposite apron as shown in the installation instructions here:
http://www.sl113.org/wiki/uploads/Electrical/RdoMtg230r.jpg
or in the attached photo.

[mdsalemi]

I have to check but on mine I believe one fuse position is for the radio, the other is unused and unwired--but was designated for the [non-existent] power antenna.

Since my car came with a USA dealer installed radio (back in 1969) I would suggest that they did not follow the said instructions you provided.  I shudder to think they did not follow the instructions!

I will certainly take a look at that photo locating to the other side, and see if it is possible w/o a horror story of re-wiring.  Good common electrical sense always says use the shortest wire possible to prevent voltage drops.

You may never have seen a "washer bottle bracket" used like that, but I've never seen a washer bottle other than one kind of tucked in and not attached to anything.  I always thought it was a bit strange and queried many people well known here who have seen my car repeatedly over the years, and everyone has always told me "that's the way it is".  Looks like mine is like  (A113 290 00 86) but does not have the "L" attachment.  But, that's what was there!  I don't precisely see how or where said bracket would or could attach to the washer bottle...will be interesting.

Guess I'll have to add some more bracket additions to my list...before or after the wiring?  

Back to your original question, since this 2-position fuse box is auxiliary--it can and could be used for nearly anything that a dealer or PO wanted.  Extra lights, auxiliary horn, auxiliary lights, added radio, antenna, etc.  If you have nothing to connect to it, don't put it back.  If it is wired to something, it should be pretty obvious, yes?  Maybe, just maybe the dealer who originally sold #5600 didn't follow directions either?  Maybe he just mounted the box where he wanted, or where it was best?

Putting a dealer added radio and or antenna and commensurate fuse box makes the most sense in the location yours is now, and mine is now--not where the instructions say.  Whether you are pulling a "+" off the ignition switch "on", or directly off the battery (always on), both of those are more easily obtainable on the driver's side of the car.  They are not, of course, by the voltage regulator or passenger side...may not match a factory wiring job on a factory installed Becker, but if you have it and I have it, maybe that's the way some dealers chose to add a radio in 1969?

[66andBlue]

..... Putting a dealer added radio and or antenna and commensurate fuse box makes the most sense in the location yours is now, and mine is now--not where the instructions say.  ....

My dear friend Michael "Noitall" Salemi, Mercedes and Becker instructions are usually well thought out and I would not second guess them so easily. 
According to one very reliable source there is a red wire in the harness on the right side where the wiring for the voltage regulator comes out that is used for the radio and when none is installed it is bent back, insulated, and tucked under the sheathing.
On my car the fuse box on the left side was indeed used for the fog lights.  The car came with a (modern) radio was hooked up via a wire that was inserted in terminal 1 in the fuse box. Not a smart idea!
I'll go back to the standard wiring, remove that fuse box and move it over to the right side and hook up a proper old Becker radio and antenna as per the instructions.  I need to find (or make) a bracket to attach the fuse box to the regulator and hope to find that red wire.  I'll let you know if I am successful.

[glenn]

Further proof that no two 113s were built the same. ..   Diversity reigns. ..(rules)

[mdsalemi]

My dear friend Michael "Noitall" Salemi, Mercedes and Becker instructions are usually well thought out and I would not second guess them so easily. 
 I'll let you know if I am successful.

My dearest friend Alfred,

I didn't suggest the instructions were not correct, nor did I suggest they were not well thought out.  I merely offered that as a dealer installed option, anything was possible. Is that hard to believe?
The mechanics probably read the instructions, looked at the wiring, and some did what they thought was best or, maybe easiest.  To think that every dealer installed radio was done precisely according to instructions, I'm afraid, is wishful thinking. Would not surprise me in the least if some dealers farmed out that installation anyway, just like many do body and paint. So, some 19 year old neer do well for Acme Radio Shoppe could have wired it up.  Who knows.

My car was wired with a dealer installed Blaupunkt (a/k/a DEfunkt) radio, in the present location of the wiring, with the auxiliary fuse box in its present location. No, it doesn't match the instructions, but that's what was done.
There is no visible "+" pigtail for power on my wiring harness near the regulator, but that doesn't mean it wasn't cut off years ago and made to disappear. For your sake, I hope you can find your "+" in the proper location to complete your project.

It's like the 3-point retractable seat belts: there is only *one* factory standard for such, but there are all manner of them out there using different parts, different brands--and probably some of these were done by a dealer's mechanic making a decision which may be contrary to the factory instructions.

The fact that you wish to bring back or rewire your radio/auxiliary fuse box to the factory standard is a noble and pure thought, and run with it if you want and can. But, are you absorbing all the answers you received here?  You asked what it was for, and the answers are as varied as the cars.  Some have it for radio, side markers, fog lights, high beams, CSS...  Get it?  It is an auxiliary fuse box and it is different things to different cars mounted in different ways to serve different functions.  I know you want one answer but there isn't one!  You are forgetting you have already received the answers to your question.  Yes many have it, and it serves different functions.

I have to echo what Glenn suggests, which quite well summed up what my restorer said when trying to get all the numerous relays for the emissions/ignition properly connected: "I've never seen two of these SLs with the same setup..."

[66andBlue]

Michael,
many thanks for the sermon, have a nice weekend!
Glenn,
our cars may have been built alike but they sure weren't delivered the same.

[49er]

OK, here are my 2 cents worth. I took a look at my car last night and I too have the mysterious fuse box like Alfred's. It was delivered without a radio but from what I remember, all radios were a dealer a installed option but all cars were factory equipped with wiring to the fuse box (yellow wire) and suppression in place. The 250 SL that I traded in on my 280 SL had a dealer installed Blaupunkt Frankfurt AM/FM/SW  radio which I removed (along with the power antenna) and installed them in my 280 myself (Luckily I had the 250's blanking plate but drilling the hole in fender of my brand new car put a few grey hairs on my young head). The antenna didn't last long so I replaced it with a J.C. Whitney antenna which required a toggle switch to operate. I also bypassed the Fog lamps switch and connected them to a toggle as well allowing me to flash my lights as our European friends were able to do. They make nice DRL's too I did all of this over 40 years ago and I could not begin to tell you how I figured it all out.

John

[66andBlue]

Hello John,
have you twisted the harness a bit to check whether the red radio wire is hidden below the main strand?
I am happy to report that I found it on my 280SL. 
Now I need to examine the 230SL a bit more carefully because on that one I have a cable that comes into the fuse box from the front like yours but is black not yellow.

[49er]

Eureka! There is a red/green wire tucked under that tape:-) Like I said, I have no idea why I wired it like I did but it all worked and I was pretty pleased with myself at the time.

John

[Wulff]

I'm responding to a respond post of yours that's 2 years old, but,   I think, has helped me today.   I've been trying to find fuses for side marker lights in my 1971 280SL,   as I've recently noticed mine are not working, and I hope it's just a fuse issue, but have not been able to find the location of the fuse in the standard fuse box! I will check out the mystery fuse box in the morning, and keep my fingers crossed. All the side marker are out, front and back!

 Does this still sound good to you?  THANK YOU!