RF wrote:
> RF wrote:
>> RF wrote:
>>> me wrote:
>>>> "RF" <RF@[EMAIL PROTECTED]
> wrote in message
>>>> news:691tvuF2t1h3qU1@[EMAIL PROTECTED]
>>>>> Roland Franzius wrote:
>>>>>> RF schrieb:
>>>>>>> Roland Franzius wrote:
>>>>>>>> RF schrieb:
>>>>>>>>> Suddenly my brake and turn lights have decided to go on strike.
>>>>>>>>> All other lights are ok.
>>>>>>>>> I did a continuity test on all the fuses and they are ok. The
>>>>>>>>> bulbs also seem ok.
>>>>>>>>>
>>>>>>>>> Anyone have a magic wand for diagnosing the root of this
problem?
>>>>>>>> Depends. Front turning lights ok? Turning and emergency lights
>>>>>>>> relais (below ash tray) ticking?
>>>>>>>>
>>>>>>> Thanks Guys. It's great to have such sup****t :-)
>>>>>>>
>>>>>>> Fuse Box: I can't find a ground on the fuse box and the wiring
>>>>>>> diagram seems not to show one. There is a screw at the lower
>>>>>>> middle of the fuse holders that seems attached to the chassis
>>>>>>> and, thinking it might be a ground, I tested it but it is not.
>>>>>>> There is an infinite resistance between it and the ground pole on
>>>>>>> the battery.
>>>>>>>
>>>>>>> Plug Connection Cable Harness: This is supposed to be somewhere
>>>>>>> at the rear of the car and I remember accessing it way back. I
>>>>>>> removed the spare wheel and the cover of the wheel well on the
>>>>>>> left side where the cable comes through to the rear but it is not
>>>>>>> there. I also removed the bulb holder brackets but no sign of it
>>>>>>> there either. Does anyone know where it is supposed to be?
>>>>>> Probably not the reason if the front lamps are dead too.
>>>>>>
>>>>>>
>>>>>>> Turning lights: All dead and no clicking when arm is moved
>>>>>>> around. Also dead: horn,
>>>>>>> blinkers, brake lights, instrument panel lights.
>>>>>>>
>>>>>>> What does work: Main lights, dipped lights, side and parking
>>>>>>> lights, radio, roof.
>>>>>> If the sunroof is working cable 15 from ignition key to fuse
>>>>>> holder and connection 15-16 inside fuseholder is ok.
>>>>>>
>>>>>> Sunroof is fuse c) and heating of back window d) at connection 16.
>>>>>> 16 is connected to 15 inside the fuse box
>>>>>>
>>>>>> All other non working (including alternator loading lamp unfused)
>>>>>> gadgets are at cable 15 at fuses 10 (air fan), 12 (fixed brake
>>>>>> warning light, brake lights, turning/warning ligths), 14 (horn,
>>>>>> backwards driving light).
>>>>>>
>>>>>> After turning the fuses in their sockets to remove oxidation check
>>>>>> the voltage at cable 15 at ignition key and the fuses. Check the
>>>>>> resistance with fuse removed.
>>>>>>
>>>>>> This is for the W123 240D.
>>>>>>
>>>>> Thank you Tiger and Roland.
>>>>>
>>>>> I struggled for over an hour with that instrument cluster. I pulled
>>>>> it out of its frame but it is very difficult to get at the nuts
>>>>> behind it and a mere half inch extra would have
>>>>> made it simple. I'll have another try tomorrow.
>>>>>
>>>>> Roland, I am a mechanical engineer and I have long since learned
>>>>> that simple mechanisms are far more reliable than any others.
>>>>> That's the reason that my sunroof, windows, seats etc. are all
>>>>> mechanical and they have never given me a problem and almost
>>>>> certainly they never will.
>>>>>
>>>>> Turning the fuses is an old and effective trick but it did not work
>>>>> for me, so the problem lies elsewhere. More work tomorrow.
>>>>>
>>>>> Thanks again for the sup****t.
>>>>
>>>> Just a couple of thoughts; did someone install a trailer hitch on
>>>> the car at some point? I have seen some horribly butchered wiring
>>>> associated with trailer lights, and grounds become problematic when
>>>> they are disturbed.
>>>>
>>>> The other thought is that certain types of bulbs were known to cause
>>>> problems in the Mercedes electrical system. I was told to only use
>>>> OSRAM bulbs in my old 300.
>>>
>>> Hi Me :-)
>>>
>>> No trailer was ever hitched to it. I have had no problems with small
>>> bulbs for years and
>>> I have never been recommended to use Osram. The four I just bought
>>> were Sylvania "Long Life." Now all I need to do is to solve my
>>> wiring problem :-)
>
A little success - I was able to disconnect the
instrument cluster.
At its rear there are the following connections:
1 A ring of pins about 1" diameter for a round
electrical plug
2 Speedometer cable
3 Oil pressure pipe
4 Three small apparently single wires - black
goes to the glow plug
light, red goes to the clock and yellow to the
seat belt light.
That's all - no sign of a ground strap or other
ground connectors.
Tiger: the signal stalk? You have lost me. I doubt
it's the arm that
does the wipers, light dips, etc. and I can't
think of anything else.
I took some voltage measurements at the fuse box,
with the ignition
in the On position and the round plug of the
instrument cluster out of
place.
Measured from the ground terminal of the battery,
fuses 2, 4 and 6 had 12v
and all others had zero. Seems like a blackout :-(
I scanned the wiring diagram into my computer and
followed
the wiring there. The battery feeds the light
switch via a black wire to the starter
and then via a red wire to the light switch. Next
the light switch feeds the ignition switch via
another red wire. Finally, the ignition switch via
a red/black wire feeds a header for fuses 8, 10,
12 and 14, which now appear to be dead.
I pulled out the light switch and discovered that
the red wire is live whether the ignition is
turned on or off. A short I guess.
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