Strange ...

[BartSt]

All,
(happy T'giving to the folks across the pond)

Following:

My instrument lights work well when I turn on lights (without ignition)

but

They also work well when I turn on ignition WITHOUT turning on the lights

Anybody has a clue?

Bart

[Cees Klumper]

Just a guess here, but it sounds like a wire (dash lights positive) is connected wrong. Or maybe a faulty ground somewhere.

[BartSt]

OK, will dive in my favourite cave ... behind the dash!!!



Bart

[lpeterssen]

Dear BartSt

Instrument lights for the speedometer and tacho should be feed through a gray/violet small diameter wire that is on the same loom as the ignition switch.

Illumination for instruments do not come from the light switch in a direct route.  From main light switch terminal 58 as far as I remember goes a gray cable to main fuse box to fuse no.8, from there it derivates in many leads, one is a gray/violet that goes to the central part of the instrument cluster where the rheostat is (dial to graduate illumination light intensity).  In some Mercedes the rheostat outputs a  gray/blue cable which feeds the illumination of many dashboard accessories.  But….. on some other Mercedes the two main round instrument dials (speedo/tachó) depending on car market or year I have seen that those are feed with a gray/violet cable that does not pass through the rheostat. In that case the grayViolet cable is a direct derivation of the cable that feeds the central instrument cluster right at the 12 pin connector female side. 

 Form that point goes as indicated before to the ignition switch harness branch.

So look for a gray/violet cable there to feed your two main instrument round dials.

Best regards
L.peterssen

[BartSt]

Mr Peterssen,

One thing I forgot to mention, and could have an impact is that my Rheostat is broken and that I created a bridge between pin 1 and 2 as mentioned in this forum.

Do you think this could influence my problem?

Bart

[lpeterssen]

Dear Bart

Not necessarily that bridge will make the trouble you are describing on the first post.

But please explain again exactly what happens, to activate my Sherlock Holmes wisdom neuronas.  I am not totally clear on which conditions make the illumination to activate in your car.

Also tell me where you made the bridge between cable gray/violet and cable gray/blue which are the input and output correspondingly of the rheostat.

If it was made at the central instrument cluster itself (the rectangular unit) back circuit board, disconnect that component from the main wiring harness at the 12 pin connector that is under the steering wheel to isolate the possible culprit and then report the results.

Best regards
Leo

[lpeterssen]

Dear Bart

As you mentioned that you bridged the rheostat since was not working, and assuming you did that either on the central instrument cluster male connector, open that connector again and check that gray/violet or gray/blue leads are not making contact with another cable that gets hot (energized) when you turn the ignition on.

Let me look at the w113 wiring diagram….

Any of the bridged leads should be making accidental contact with blue/red or blue cable which provide energy to central instrument cluster when the ignition is on.  Blue red comes from the non-fused side of the circuit no.2, and blue comes from the fused side of the same circuit.

Remove fuse no.2 and see what happens.

There is your culprit.

Best regards
Leo.

[BartSt]

Leo,

(Good morning from a rainy Belgium)

Will do so and report back asap.

Be well,

Bart

[lpeterssen]

Dear Bart

Regard from a sunny morning in Venezuela.

Take care, and any other question feel free to write me per DM.

Regards
Leo

[BartSt]

But please explain again exactly what happens, to activate my Sherlock Holmes wisdom neuronas.  I am not totally clear on which conditions make the illumination to activate in your car.

---> I have a 230SL, redone the engine, and fixed some wiring problems. Now when the lights are turned off and I will start the ignition (without starting) the dash will light up. Once I started the car the dash lights will remain on, even when the headlights are off.

Also tell me where you made the bridge between cable gray/violet and cable gray/blue which are the input and output correspondingly of the rheostat.

---> this is what I did (via https://www.sl113.org/wiki/Electrical/Rheostat):

Shorting out the Rheostat

Disconnect the Battery!
Disconnect the “12 prong plug” on the metal bracket that the “Flasher Can” also hangs on.
Remove the cover off the back of the male plug (3 screws on a 230 or snaps-off on 250 and 280's.
Remove the two wires that go up to the rheostat. One is grey w/violet stripe the other grey w/blue stripe.
Hold each terminal pin with a pair of needle nose pliers, heat with a soldering iron until the wire pulls out. While the solder is still hot tap it against the floor and the excess solder will come out and clear the holes.
Make a short (insulated) jumper wire and solder it with the original wires in the terminals.
Replace the terminal pins back in the plug where they came out.
Reinstall the cover on the back of the plug.
Reconnect the “12 prong plug”.
Reconnect the Battery and check for operation of your dash lights.
The photos below were taken on the workbench, but the job could easily be done in the car with the steering wheel removed.


https://www.sl113.org/wiki/Electrical/Rheostat?action=download&upname=reo1a.jpg
https://www.sl113.org/wiki/Electrical/Rheostat?action=download&upname=reo3a.jpg

If it was made at the central instrument cluster itself (the rectangular unit) back circuit board, disconnect that component from the main wiring harness at the 12 pin connector that is under the steering wheel to isolate the possible culprit and then report the results.

Hope this already helps a bit

Bart

[lpeterssen]

Dear Bart

If you did exactly what is explained on that rheostat bridge procedure described on the link there are very few possibilities that the problem origin is there.


First disconnect the cable branch that goes to central instrument cluster (12 pin male connector) from the connector at the main wiring harness.

Indicate if with that disconnected we still have illumination coming on on the speedometer, tachometer and heater levers when you turn ignition on..


After this … do this other idea…

We have to find first which circuit from all that have power when ignition is on is providing energy to your instrument illumination leads.

Repeat this as many times as necessary to find the culprit circuit and then dig further with my guidance:

1. Turn ignition off
2. Remove fuse no.2
3. Turn ignition on again, check if illumination comes on….., if the answer is yes proceed
4. Turn off
5. Replace fuse 2, and remove fuse 3
6. Again return ignition to on position and see if illumination comes on, if answer is yes continue, if answer is no report circuit 3 as the origin of the power coming accidentally to illumination.
7. If answer above was still illumination on, continue disconnecting ignition and replacing fuse 4, and so on.

Of course when you come to fuse 8, when removed illumination should go off.

Start experiment and report.

Best regards
Leo

[BartSt]

Yes sir!

[BartSt]

Leo,

I solved 75% of the problem ...

Once I disconnected the cigarette lighter from the fuse box my problem was solved .. only for the main lights of the dashboard.
My heating levers are still on when I make ignition without the headlights switch on ...

So when I turn on my lights the lights of the dash (speedo, tach and center) nicely turn on as well ...

Any thoughts?

Bart

[lpeterssen]

Hello my friend

Let me study the case with your actual leads or clues to try to guide you just to the right point. I ve been out doing errands all the day.

Best regards
Leo

[lpeterssen]

Bart

Cigarette lighter is fed trough the fuse no.2.  That was the case in your car?

When you removed that fuse no.2 lights at the central square cluster, lights at speedo and tacho went out, right?

Best regards
L.peterssen

[lpeterssen]

Bart

I know I know I know. Yuppi

The branch that goes to the cigarette lighter also has two additional leads that feed the light at the ashtray.

Try to disconnect that branch that is connected to the cigarette lighter and ashtray light.  You should make a repair inside it.  The cable insulation of the gray/blue cable that goes to that point is damaged somewhere in that branch.

Remove all the plastic insulation pvc (black) jacket that is around those 4 cables and find where the gray/blue cable is broken in that segment.

Regarding the heating levers light, that connection comes from the same branch that goes to the ignition switch. As ignition switch has many powered cables, that cable gray /blue is also broken somewhere there and is making contact with the cable red/black coming out from ignition switch to the main fuse box.

I think that is time to do a full restoration of your wiring harness.  It has many gremlins.

I do that for my friends at a reasonable cost, send me a direct message

Best regards
Leo

[lpeterssen]

Bart

Cable colours for your reference.

1. Black / green / yellow = 12v feed to cigarette lighter, comes from fuse 2
2. Brown, ground for it

3. Gray/blue, 12v feed for ashtray light,
4. Brown, ground for it, passing trough cigarette lighter connector in a loop connection

All these 4 leads travel together inside the same pvc tubbing.

Best regards
Leo

[BartSt]

Leo, thanks again.

Will first give this a try before I think about a new harnas. Have been working on the car for months, feel I'm almost there ...

Hope you understand

Bart

[lpeterssen]

Bart

No problem, sooner or later you will need to refurbish that harness, and I am the engineer for that.

Best regards
L.peterssen

[lpeterssen]

Bart

In order to make the necessary repair to your harness by yourself, keep the main fuse box in place but remove all the part of the harness that is connected to main light switch, ignition switch, and other accesories behind the dashboard.

In that way you will have enough length out to work the areas, branches suspect of cable isolation problems.

With the harness fully installed in place the repair will be too poor since there is not enough place to maneuver and to fully remove pvc tubing and inspect each of the cables in detail.

In my opinion the full illumination wire lines should be replaced for new ones.  It is very common to see on old harness those lines melted.  They are prone to that because there is an easy source of short circuits on the connection behind the main instrument spheres illumination bulbs.

Be patient and you will manage to make a good repair.

All connections should be soldered from one connector to the next one.  Not good to have in between splices.

The gauge for those cables gray/blue is very thin.  Awg18 is enough.

Best regards
Leo

[BartSt]

Leo,

Hi, I promised to give you an update. Here we go.

So I bought this (US) car from a guy in Berlin (who never drove) it and who bought it from a guy in the UK who bought the car in the US.

When I bought it I pulled the engine out and noticed some abnormalities (small screws which were not original etc)
Then when I redid the engine and replaced it, I started to re-connect the hoses, fuel lines and electrical wiring.

When we did our first re-start we quite quickly saw some burned red wires hidden under the dash.

Then it all started going south, and one thing after another became visible.

But with your help (and my neighbour) I was able to fix a lot of problems.

One of the last problems to fix was the light at the heat sliders.

I looked at your comments, had a real close look at the coloured wiring diagram, made copies, wrote down all colours etc.

Once I got at my car I started at the cigarette lighter (as it is connected to the lights) and then I saw something strange ... the colour codes did not match the diagram ... the inverted the plugs !!! The cigarette lighter plug was connected to heater lights and the heather lights to the cigarette lighter. Therefore I had 12v on ignition at the heather lights ... (what the previous owner also did was connect a wire to fuse 2 and link it as a 3rd wire to the cigarette lighter, so he had constant 12 volt ...)

So Leo I'm sorry I bothered you with this, my car is just a mess with very clumsy people working on it

I think all is solved, but I only know when I start driving it, so will keep you updated in due course.

Enjoy the warm weather. Greeting from a country with wet snow!



Bart

[lpeterssen]

Bart

It s great to hear that you advanced so much on the electrical….always forgotten on many restorations and guilty of many many problems that have no explanation.

Continue making your best on that in order to have a reliable and safe drive.

No problem with your question, I enjoy them since activates my neurons trying to find out what is wrong without having direct contact with it just by reading the symptoms reported by end user, which in most of the cases are not complete enough.

Regarding the high beam definitely as is a USA spec car the problem is related to the white/violet cable not connected on port no.10.

Feel free to write me directly to report the progress.

Best regards
Leo.

[lpeterssen]

Bart

Something I still do not understand…..

1. When we disconnected the cigarette lighter fuse no.2 illumination at main round and rectangular instrument units went out
2. My guess was that feed cable black/green/yellow was making accidental contact to one gray/blue cable inside any of the pvc tubing branches going to those accesories, since they share the same route.

You say…

3. The 2 prong plug for the cigarette lighter was connected on the illumination port for the heater levers, which perfectly explains why they were always on with ignition activated, as circuit no,2 is a T15 circuit.

But… if fuse no.2 was removed…… why the cigarette lighter connector had power?

Unless….

I do not get the clue

[BartSt]

You are right ...
Dunno what happened/is happeing
So I believe this story is not yet finished.

Maybe you have to ship a new set from Venezuela to Belgium in time ...

(I think we also would make history "The first ever 230SL loom shipped from Caracas to Antwerp")

Keep in contact,

Bart

[lpeterssen]

Bart

That is history already.  I have sold one harness to Belgium already, and to Japan, 2 x for Kenia, 3 x to Australia, 2x UK, Poland, and many many to USA.

JOJOJOJO

BEST regards
Leo