Re: 240D lights problem


"RF" <RF@xxxxxxxxx> wrote in message
news:691tvuF2t1h3qU1@xxxxxxxxxxxxxxxxxxxxx
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 support :-)

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 support.

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.


.

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  • Re: 240D lights problem
    ... Front turning lights ok? ... Turning and emergency lights relais ticking? ... Fuse Box: I can't find a ground on the fuse box and the wiring diagram seems not to show one. ... The other thought is that certain types of bulbs were known to cause problems in the Mercedes electrical system. ...
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  • Re: 240D lights problem
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