Anyone with an electric mystery needed to be solved

[lpeterssen]

Hello my friends

Happy new year, ready to help you out on any erratic and unexplained electrical behavior of your loved classic car.

Remember electricals are allways the Cinderella on any restoration, everybody is afraid of touching it, and is full of “band aid” repair's..

Get your hands fully on it and give your electrical system the attention it deserves.

Any questions are welcome. Will answer them right away trough this forum.  Remember to make a good explanation of how, when, and what happens to your electrical system that you consider is a misbehaving case.  All clues will be needed to solve each puzzle.

Look at this album:

https://www.icloud.com/sharedalbum/#B0QGWBC59GSmN4U


Best regards
L.peterssen

[BartSt]

(all HNY)

I can share with you from experience, that Mr Peterssen is extremely helpful and knowledgeable.

He helped me a lot with my Non Cinderella electrical spaghetti.

Be well,

Bart

[lpeterssen]

HNY Bart

Many thanks for your kind comments.

Be well.

Best regards
L.peterssen

[Bonnyboy]

I do have a question....do you have a picture of the little wiring harness that lights up the heater levers and speedo and tach etc.   My car is missing part of the in-dash harness but I may have it in a bag of wires that I swept up off the floor when I picked up my car long ago.   

[lpeterssen]

Dear Ian:

That is a frequent problem on the wiring of classic Mercedes w113 and similar cars.  There is not a separated sub wiring harness for the speedo& tacho illumination as well for the heating controls.

It is common to have those cables chopped.   

Supposing that cables are still there but hidden, let’s solve first the speedo&tacho.

TACHO

There is a pair of cables coming from the main light switch harness branch that has a gray/blue cable and another brown which is the ground.  Those should be connected  to the bulb holder which is behind your tacho (gray/blue is the positive 12v) and the brown should be connected to the tacho housing.

SPEEDO

On the harness branch that goes to the ignition tumbler switch there is again a pair of cables with same Colour scheme as described before. Gray/blue + brown.   Do the same thing done on the tacho.

HEATING CONTROLS

On the harness branch that goes to the cigarette lighter there are 2x double prong female connectors. One of those connectors has a black/yellow/green cable+ one brown .  This connector is for the cigarette lighter.  The other connector in that same branch  has one gray/blue cable  and one brown.   That terminal connector should go to the heating sliding controls illumination  connector.

Look at the picture attached which has two red circles. Those are the harness branches for the main light switch and the ignition tumbler mentioned above.


WORKAROUND in the case you can’t find any gray/blue cables.
=======================================

Gray/blue cables are always related to illumination circuits on classic MB.  If your car central instrument cluster (rectangle part between tacho and speedo) illuminates when you turn on the exterior driving lamps, there is a good chance that we can obtain a derivation cable to illuminate the accessories asked by you.  I mean a dimmeable illumination  line coming from the output of the rheostat.

You just have to open the 12 pin connector that feeds the central instrument cluster.  In that connector you will have to look for a gray/blue cable and solder there the derivation cable you want to use for the bulbs holder already mentioned.

If you are not very handy soldering, there is a much easier solution but with one compromise.  The lights will not be dimmeable at the speedo, tacho and heating controls.  That is a small sacrifice for functionality considering the risk of doing a lousy job soldering in those connectors and affecting other circuits.

So I think this will be the best approach for an aficionado.

EASY SOLUTION

===========

Take the illumination line from fuse no,7 output on the main fuse box.   You will notice, that from main fuse box, circuit no.7 there are three output cables. Two of them are gray/red and there is a single gray/violet.

Prepare one derivation cable that will feed the illumination  on the accessories requested (tacho, speedo, heating) with an “0” shaped terminal on one side.  Unscrew the cables on fuse no.7 and place on that screw the 4x cables,  (2 gray/red + 1 gray/violet and 1 x new cable.).

Remember that each of the accessories which need to be illuminated also will need a good ground cable.

Enjoy your modification work.

Best regards
L.peterssen

[johnk]

L.Petersen has been a big help for me too.

[lpeterssen]

John

Happy new year. Many thanks for your nice comments.

Best regards
L.peterssen

[Kevkeller]

Hi,
I see you have an electrical diagram on your iPad or device. Would you be able to share a copy of that?
Thank you and Happy New Year.
Kevin
1970 280SL

[BartSt]

Is just the PDF from the Technical Manual

Bart

[lpeterssen]

Kevin

As indicated by Bart, that wiring diagram I use most of the time when servicing w113 wiring harnesses, is on the technical section of this forum.  It is available for full members only.

Nevertheless there are similar published on the internet and you can find them doing a query for “Mercedes W113 wiring diagram”. Be aware that there are several versions depending of year of manufacture, but they are indeed very similar for general purposes.

Best regards
L.peterssen

[Pawel66]

Hi,
I see you have an electrical diagram on your iPad or device. Would you be able to share a copy of that?
Thank you and Happy New Year.
Kevin
1970 280SL

You are a Full Member!
https://www.sl113.org/wiki/Electrical/WiringDiagram

[Kevkeller]

Thank you gents.

[Vintelectra]

Hi.my 64 230 sl wiper motor not working. Power gets to motor terminals when activated.Brushes good.How do I check for motor continuity? Thanks in advance. Martin

[lpeterssen]

Dear Friend (vinelectra)

If you already checked that there is power to the carbon brushes when active, there is nothing else you can do but to bring the motor to a rebuilder to rewind (hacer embobinado)

The motor is dead so should be repaired.

Clean the collector at the inductor, to see if it works.

https://www.google.com/search?q=working+of+an+electric+dc+motor&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari#fpstate=ive&vld=cid:44acf7ae,vid:CWulQ1ZSE3c


Best regards
L.peterssen

[Adrian53402Aviles]

Dear Sir, I own a 1965 230 that I bought as a project. The car is completely empty with the wiring harness in place. My question is, is there a photo diagram of which wires go where and what order would you recommend I begin with. The steering column is not installed thereby making access a lot easier. My experience is with 60's muscle cars and trucks, completely different animals than what I'm used to working on, Thanks Adrian

[BobH]

Hello, wiring schematics are on here:

https://www.sl113.org/wiki/Electrical/WiringDiagram

https://www.sl113.org/wiki/Restricted/ColorWiringDiagrams

Depends on the year of manufacture which diagram is relevant to your 230, note the main schematics are for manual cars, if you have an auto, it shows the differences on the smaller schematic

Can't help you with the order of connections, hopefully it will become clear when you look at the schematic

[gunbarrel1]

Hello. I am Tim at Gunbarrel
Imports.  I have a real interesting electrical nightmare in a manner of writing.  There is a 1969 280SL in the shop currently.  When it arrived, the car seemed to run okay, but there was literally a pushbutton switch under the dash to operate the cold start valve, and fuse #1 was not installed.  I successfully straightened out the cold start system, and removed the pushbutton.  Upon inserting fuse #1, I found that the engine would continue to run if the ignition switch was moved to position 0 with the door open.  The door open indicator was illuminated all the time, and the light above flickered.  Upon investigation, I found that , with the door open, there was a short between the load side of fuse 1, and the supply side of fuses 2, 3, 4, 5, and 6. I found two literal meltdowns in the wiring harness beneath the driver's side dash/above the pedals area.  The most severely damaged wires seem to be the grey/blue wires associated with interior lighting.
Even after separating the melted wiring, the short between fuse 1 (terminal 30) and the subsequent five fuses (terminals 15/54) did not disappear until the brake fluid level sensors were unplugged.
It is perplexing to me why the brake fluid level sensors should be supplied power when the door is open, but unless I misread the wiring diagram, it is the case.
Having written that, The melted wiring was associated with the twelve pin connector fastened with three screws to the metal plate which houses another clipped twelve pin connector, and the turn signal flasher.  It was both above the hood release, and again on the other side of the twelve pin connector, fastened with screws to the metal plate, as the wiring rises behind the instruments. 
I have separated out the wiring, and performed replacement of the damaged portions of wiring.
My main question is:  Is there an accurate pinout of the wiring positions in the twelve pin connector attached with three screws to the metal plate? When I removed the connector from the plate, some of the pins popped out, and I would like to insure that the pins are inserted in the correct position.  I do not see this twelve pin connector represented on the wiring diagram or in the technical manual.
Also, when the wiring was separated , and the brake fluid reservoir sensors disconnected, there was approximately 35 ohms of resistance between the load side of fuse 1 and the supply side of the 15/54 fuses.  The resistance also measured approximately 35 ohms with the door closed, so  I know that it is enough to shut off the engine, but is it a correct reading?
Any help or advice you might have is greatly appreciated.  Thank you.

[BobH]

Hello Tim, you'll see on the wiring schematic that the door open and low brake fluid level both use the same warning lamp on the instrument cluster, hence when the fluid is low, or a float has sunk, possibly due to a hole in it, and the door is open, a +ve feeds back to the fuses and ignition switch.  A diode in line will fix the problem

Have a look on here for the back feed problem, and on the other two links for the 12 pin connector wire colours

https://www.sl113.org/wiki/Brake/LowFluidWarningLight

https://www.sl113.org/wiki/Electrical/InstrumentCluster

https://www.sl113.org/wiki/Electrical/SteeringColumnSwitch

[gunbarrel1]

Thank you BobH.  Those links were exactly what I needed.  My biggest problems are just about resolved, but I do have a few more questions.
When the car arrived, there were many loose wires in the engine compartment, some of which helped resolve the problems with the cold start system when they were attached. (including the bundle of ground wires which bolt to the relay bracket on the left side, above the windshield wiper relay)
There is still a green wire, wrapped in black vinyl which comes out of the harness next to the injection pump on the left side of the engine compartment.  I have not been able to find a home for this wire which has a small ring terminal on the end.  I was thinking maybe tach signal, but the tach works after the wiring repair.
Also on the right side of the engine compartment, next to the coolant expansion tank, there are two wires which protrude from the factory wiring harness.  One is red, and always has power. (terminal 30)  There is another which is red with a green trace which switches power with the key. (terminal 15)  The brilliant air conditioner installers had them twisted together, and attached to the A/C system.  Are these wires provided to facilitate aftermarket A/C installation?  Is there another purpose for these wires?  I will not try to repair the aftermarket air conditioner right now, as the refrigerant hoses are substandard at best, and the compressor pulley makes a high pitch whining noise.
Once again, thank you (profoundly), and any additional help is greatly appreciated.
Tim

[lpeterssen]

Dear Tim

Those red and red/green wires are for the power antenna / radio installation.  They should be matched to an auxiliary 2 port fuse box. 

They can not be used to feed energy to an AC system since their gauge is very small.

Best regards
Eng Leonardo Peterssen
Www.wiredoktor.com

[lpeterssen]

Dear Tim

Regarding the green wires next to the mechanical fuel injection pump we need to know which year is your w113-280SL

I think that line is related to the fuel cut off selenoid which is part of the emission control
System.

Make a search on this forum for EMISSION CONTROL system and read and learn all you can about it.

Then come to your own conclusion if you want it to be wired on or not.

Best regards
Eng Leonardo Peterssen
Www.wiredoktor.com