Author Topic: Wiring issues 101 (Read 34798 times)

J. Huber · « **on:** March 18, 2009, 17:02:29 »

So, in the midst of re-installing my dash instruments, I discovered two things (at least) that are not working now. The first is my flash to pass and the second is the blue high beam indicator on the center instrument. I took a look at the mess of wiries under the dash just now -- and guess what. Two wires that looks deep fried. That possibly explains the puff of smoke when I tired the flash to pass after the install... I then wisely pulled out the fantastic color wiring diagram from one of the Pagoda World issues...Sure enough. The two burnt (exposed) wires match exactly. Nummers 29b and 10h. Aha.

So now what? How does one next deal with the half-baked wires? They are not broken but the wire is exposed in places and the plastic kind of crunchy.

jeffc280sl · « **Reply #1 on:** March 18, 2009, 17:43:11 »

What do you think caused the short? That needs to be identified and fixed. When repairing the wire I would try and identify a terminal that the crispy wire ends at. The other side of the terminal should be good wire. A terminal may also end up being the fuse block. Try and source a piece of wire the same color and gauge and splice it into place. If you have to make repairs on an open wire I would solder the connection to new wire and use shrink wrap to insulate the connection. All repairs need to be made with the battery disconnected.

J. Huber · « **Reply #2 on:** March 18, 2009, 17:52:17 »

Hey Jeff. Thanks for chiming in... I can't really say what caused the short to happen. I was in the midst of getting the gauges back, fiddling here and there with the dash bulb wires and grounds, etc to reconnect everything. As you know, its kind of tight in there. My wiring confluence under the dash is quite a spaghetti feed -- don't know if others are like that. Anyway, is it possible one bare wire then fired the second wire? The fuses are not blowing -- and the flash to pass seems to work for a second then not at all. The blue hi-beam light is not on.

It all seems to be on the fuse side of the large pin connectors -- if that helps.

J. Huber · « **Reply #3 on:** March 18, 2009, 18:25:30 »

As I look at the wires, its possible the wire for the flash is broken. Addressing this one first, if I can isolate the bad stretch of wire -- is it possible cut it out and then using butt connectors, splice a new section in of same size (& color if possible) wire?

I am trying to circumvent soldering for the moment. That will be the more permanent fix but I either have to farm it out or learn to do it. Now, a crimp I can do!

Peter van Es · « **Reply #4 on:** March 18, 2009, 18:49:56 »

I'm so glad you're calling this 101. A couple of sections Bob Possel and I contributed to the Technical Manual:

Simple, but do check it out!

Peter

waltklatt · « **Reply #5 on:** March 18, 2009, 19:08:23 »

J. Huber,
Check the turn signal stalk too. If I remember correctly, you restored the steering wheel and took out the turn signal stalk. Might be a wire caught up in there. or a wire crossed. Open up the big bakelight connectors to see if the wires are not touching the barest or an errant strand of wire tiptoeing over to another.
My first job on a Mercedes at 12 yrs of age was to rewire a 1966 230SL, where someone cobbled the wires for the radio and promptly fried the entire dash. That was my introduction to the W113SL's and a love affair later.
Walter
1967 220SL-diesel

J. Huber · « **Reply #6 on:** March 18, 2009, 19:09:34 »

Hi Peter. Thanks -- although the first wiki page is over my head (so far), the one about grounds I think I almost understand. Which has me thinking. Could this be:

1. I just re-painted some of my engine bay. I may have painted over the ground behind the Voltage Regulator. However, the VR and the auxillary fuse box seem to be working. Don't tell me that would affect wires under the dash...

--- So I just unpainted the ground under auxiliary box. Still no activity to the lights -- although could that have been the cause of the short? and now I need to repair the wires to find out?? Humor me guys -- I have exactly two and a half days until Spring driving season starts...

Peter van Es · « **Reply #7 on:** March 18, 2009, 22:14:50 »

James

Your probems could be the result of:

a simple bad ground, in which case you need to check for un-insulated wires or touching connectors
a faulty switch, in which case you need to measure if voltage is applied to the output you are expecting to get voltage on
a miswired connector (did any of your connectors open up during removal and re-assembly ? Check this page http://www.sl113.org/wiki/pmwiki.php?n=Electrical.Connectors and especially the link next to the light-bulb
voodoo, as is often the case with electrical circuits. Buy me a flight to come fix it for you (I expect lodging and three square meals a day of course) and I promise I won't leave till its done

Peter

J. Huber · « **Reply #8 on:** March 19, 2009, 17:45:27 »

Thank you to everyone helping out. Sadly, this has turned from the ridiculous to the sublime, or something like that...

Being the impatient type, I got under the dash yesterday and removed a section of the two wires that looked damaged. The Hi-Beam indicator wire seemed to have clearly exposed wire, the other wire was not bad but I spliced anyway. For now, I used a wire connector but talked to my alternator guy who will solder them for me soon.

Problem is -- removing the broken wire did not change a thing. So I went to bed last night thinking -- maybe it is the bulb in the temp gauge after all. Worst case scenerio -- no hi beam indicator for now and I can remove gauges again and check the bulb later.

NOT!

Today, I went to start the car -- and the starter not only dragged very slowly but continued to crawl after I pulled the key. What's That all about? Initially, the lights worked -- so it was not the battery. In disbelief I tried it again...same thing. I tried the tap the starter trick -- now I have nothing. Zilch. Dead on Arrival. I checked battery connections. I did not have much time (stupid job thing) -- but I crawled under to look at starter wires.

How many wires should be on the starter?? I saw a white one, and an empty blue connector...Is there supposed to be a wire in that one??

I am nearing the "car for sale" territory! -- as I am in over my head. And I am not particularly happy about it (can you tell?).

waltklatt · « **Reply #9 on:** March 19, 2009, 19:39:38 »

James,
Ouch! I wouldn't go that far for the "for sale" territory.
I would look at the starter again and look around at the wires.
There should be a purple wire(pencil thickness or a bit smaller) (that one is the activator wire from the ignition switch),
Then you have a big thick wire that is obviously to the battery, and then a small thin wire....hmmm.
My mind is fried at the moment.
I'll consult my electrical wire diagram at home.
Sorry about that, I've had a week from hell with work and I'm brain fried.
Walter
1967 220SL-diesel

Peter van Es · « **Reply #10 on:** March 19, 2009, 20:18:01 »

James...

that could be caused by a short circuit somewhere (you messing with the wires making an exposed wire touch a bit of metal, creating a ground-short). That would drain the battery and give you starting problems. Your starter (which requires a strong current) will fail well before your headlights. Use the instructions for Finding a short circuit or battery drain from the Wiki (http://www.sl113.org/wiki/Electrical/Troubleshooting) to try and fix this.

If you haven't touched the starter wires, do not suspect that. I would suspect switches near the dashboard. In the past I had a problem which stumped me for a week or so... and I'm an electrical engineer. Everything seemed to work, but after a while my indicators stopped working and burnt out my flasher relay. It turned out that the guy who had done some bodywork around the headlights had pulled one of the connectors apart and wired up the connector wrong... It appeared to work, but after a while when the frame of the headlight got a proper ground to the chassis, it created a short circuit which fried said relay.

The moment I pulled the headlight away from the chassis, it looked like it was all correct. The moment I put it back in, it failed. He had switched just two of the connector posts which meant that when I indicated left I had +12V directly attached to the chassis.

After solving that problem I added this page to the Wiki: http://www.sl113.org/wiki/Electrical/Connectors. Have a look at the document next to the lightbulb. If any of your connectors have been apart, verify them wire by wire, post by post, against that document. If they have not been apart, are you sure?

If this all fails, do not sell your car. Trailer your car to Blacklick instead...

Peter

J. Huber · « **Reply #11 on:** March 19, 2009, 21:02:50 »

Ok. Not for sale (yet!)

I'll be regrouping shortly...

One quick question -- on the back of the center cluster instrument there was a wire. I put it on the left hand post then the bracket, then the nut. Does this sound correct?

Peter van Es · « **Reply #12 on:** March 19, 2009, 21:26:58 »

About that center cluster wire, I wouldn't know. It sounds like you are grounding it. Are you sure it was grounded before ? Perhaps you ought to verify that first.

Check this also: http://www.sl113.org/wiki/Electrical/Lightswitch#Column

Peter

Mike Hughes · « **Reply #13 on:** March 19, 2009, 21:44:57 »

James -

There are at least two, and sometimes three, wiring harness ground wires that are secured by the thumb nuts on the back of the instruments. You would not believe the strange things that can happen when ground wires are left suspended behind the dash instead of being grounded through the instrument securing brackets to the metal dash. If it happens to ba a common ground for several circuits, one component can actually ground out through another seemingly unrelated component with variable, but almost always interesting results. I have not personally experienced this on my Pagoda, but let me relate to you what happened when I failed to secure a similar ground wire to the back of an instrument that I replaced on my sister's MGB-GT many years ago: when she hit the horn switch or flicked the electric overdrive switch the high beams would flash, flicking the high beam stalk to engage high beams would dim all the lights, but neither the electric overdrive nor the horns would function at all, unless you put the car in reverse! Then the horns would blow, at least until the reverse lamps blew out! Simply finding the ground wire and securing it to one of the instrument clamps cured all these problems and everything returned to normal function once the reverse lamps bulbs that had been pressed into short lived service as fuses had been replaced. Now let's not start a thread about "Joseph Lucas, the King of Darkness," etc. Most automotive electrical problems regardless of component brand can often be traced to faulty grounds and poor connections, or failure to reconnect things properly when reassembling something taken apart!

J. Huber · « **Reply #14 on:** March 20, 2009, 00:43:24 »

Thanks again -- keep the info coming!

As I am away from the car -- a few new thoughts:

1. I just read a bit in the wiki about pin connectors. This is a crazy thought but can the connector be fitted completely backwards? As it is now, the two large bakelite connectors under dash are facing same way. For some reason I had a flashback to them facing opposing directions! Is this possible? Can anyone confirm the orientation? Or maybe its not even possible to reverse it? The connector from the center cluster is the one I had taken off.

2. The terminals at the fuse box. If I had a loose connection terminal from behind (under the dash) would this drain the battery? Not sure I do but wondered.

Oh and Walt -- about the turn signal stalk -- I never did have it apart.

Peter van Es · « **Reply #15 on:** March 20, 2009, 08:47:33 »

Re 1: if it is symmetrical, yes you could have. Is it the big 14 prong connector you are talking about? The way both these big connectors are mounted under the dash is such that the wires from the plug are facing the opposite direction of the wires of the socket. If the wires of both the plug and the socket are on the same side, you have it plugged in incorrectly. Check that first, it might be an easy fix!

Re 2: yes sir, it could indeed. When I bought my car first, I had intermittent starting problems. And a permanently low battery. I finally did the "find the short circuit" test, and narrowed it down to something under the dash. A previous owner had a powered car phone installed, and ripped it out. The remaining +12V charging wire had been wrapped with a little isolation tape. The heat hat made that come loose. Occasionally (not always) it would touch metal under the dash, creating a short, draining the battery. That caused my problems. Onece I'd found that wire, I removed it completely. No more problems since.

Peter

J. Huber · « **Reply #16 on:** March 20, 2009, 14:10:48 »

Well, Peter. So much for easy fix. Yes 14 prongers. It looks to me like they only fit on one way -- yes one side has bundle to unit, other side the other direction.

There are two 14 prong plugs side by side. The plug closest to firewall is to the steering column. The one closer to driver is to the center gauge. Please someone tell me that is correct!

Anyway, since battery is apparently dead -- I cannot test anything until I get it recharged, correct?. I removed steering wheel and tach AGAIN. Just to see better. I am betting something heading to fuse 1 is draining the system. Just a hinch since the flash to pass wire was fried, there was a puff of smoke when I tested it initially... But how could it drain battery when lights were off?

Peter van Es · « **Reply #17 on:** March 20, 2009, 14:56:16 »

James,

it becomes guessing now. The two connectors you see, I think the 14 prong one is for the Steering Line Assembly and the Warner blinking system. It should go into the steering column.

The connector document http://www.sl113.org/wiki/Electrical/Connectors does not apply completely to the 280 SL/8 (see first page). It's the only one I have though, unless someone can send me a new pdf. I reckon it is incorrect for the instrument cluster, as we appear to have a rectangular plug and the document refers to a round plug. From the wiring diagram our instrument panel plug should have 12 leads, which means it should be smaller than the other connector.

For me the larger connector is closest to the firewall, but the sockets and prongs should obviously line up and match up. Given that they are different sizes you should be able to figure out which goes where.

I cannot really tell where my wire-bundles are headed exactly as I do have all my instruments in and it's a rats nest up there with the addition of all sort of alarm wiring.

Sorry I can't be of more help... Perhaps Bob Possel could chime in?

Peter

J. Huber · « **Reply #18 on:** March 20, 2009, 15:25:33 »

Well Peter, first off I can't count. Both are 12 prongs. I am going to continue to study things today. Glad to hear you have a rat's nest too (only because misery loves company)...

If anyone is brave enough to take my troubles off-line, that would be great.
In any event, I'll be back.

Naj ✝︎ · « **Reply #19 on:** March 20, 2009, 17:44:53 »

Hello, James,

I hope the pictures helps. Can't tell which is which but the plug on the left looks smaller?

naj

J. Huber · « **Reply #20 on:** March 20, 2009, 19:44:30 »

Thanks Naj. -- Unlike your pics my two plugs are identical from the top! I am away from car but it looks like the steering column plug and the round blinker unit go next to each other. That means the instrument cluster is closer to driver -- which is what I have...

So here is a recap and what has me puzzled. A week ago, everything was normal except I had no high beam indicator and no headlamp flasher.

I find two damaged looking wires, cut out a section and resplice them together, respectively. One was the headlamp flasher -- the other was actually the charging light (not the hi-beam) ... Next day, battery completely drained... Is my splicing to blame?

J. Huber · « **Reply #21 on:** March 21, 2009, 15:36:30 »

Hi. Does anyone who recently played with their center cluster unit remember a thin black wire with an eyelet at the back? If so, where and what? Please. Thanks.

Peter van Es · « **Reply #22 on:** March 21, 2009, 16:32:56 »

Mine looks exactly like Naj's... (but more in focus

) that's why I wrote what I wrote: a 14 prong and a 12 prong.

If you spliced two wires AND have NO blank bits of wire capable of touching bits of metal, you should be ok (unless you did it wrong and spliced one bit of wire 1 to the other bit of wire 2 and vice versa... think back over how you did it and you'll know).

Wires with an eyelet are typically meant to ground things.

However, given that your plugs look nothing like mine, perhaps I ought to stop writing and you ought to stop reading my drivel.

Peter

glenn · « **Reply #23 on:** March 21, 2009, 16:38:09 »

Wiring systems on the 111, 113, pontoons, 50s and 60s MBs all seem prone to wiring fires. Many wires were packed in electrical tape bundles. Flexing and age resulted in shorts, etc. Wire insulation failed. Not to mention - PO and CO 'improvements'. A fact of life.

waqas · « **Reply #24 on:** March 21, 2009, 16:53:04 »

Aren't there differences in the harness/plug arrangements of 230SL vs. 280SL ?

James, sorry I can't send you a pic of my 230SL plugs (am very far away from car right now).

Regarding the wires you spliced, do you remember what kind of damage you saw? (electrical/heat damage, or mechanical?) Things in that area don't usually vibrate independently of one another to cause such severe mechanical damage to the wiring.

As far as I remember, the thin wires with eyelets went to the speedo and tach and attached underneath the centre knurled nut, to provide a ground connection for the speed/tach light bulbs.

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Author Topic: Wiring issues 101 (Read 34798 times)

jeffc280sl

glenn