On my brand new 1988 w124, the orange 'broken light' indicator comes on
intermittently. The manual says it should come on when a light is
activated and one of the bulbs is broken. None of the lights seem to be
broken however and I'm not switching anything on or off when it comes on.
Any idea what's the most likely cause of this?
One or more lights are not functioning correctly because of a poor
electrical contact. Turn the ignition switch to the ON position. Check
the rear lights by opening the trunk and twisting the sockets slightly.
Simultaneously observe the 'broken light indicator' through the rear
window. The bad lamp indicator should turn ON and OFF when you move the
'intermittent' connection. The little tabs of the bad socket are not
making a good contact. It would help if someone is looking at both the
front and rear lights while you test them. I am pretty sure that there
is only one that is intermittent...
It happens when an electrical contact is borderline bad. It becomes
intermittent and it cures itself when the weather is hot or cold... who
I had the same problem with the right rear stop light in my SLK230. It
was fine for weeks at a time and then, on a hot day, there it failed
again. In my case it was the printed circuit board that is part of the
tail assembly. The bulb is mounted in a socket and the socket's
contacts 'slide' in the printed circuit traces when twisted. The PCB
trace was damaged and made an imperfect contact that often healed itself
as it expanded and/or contracted due to temperature changes. To fix it,
I had to remove the whole light's tail assembly and repair the bad
trace. The socket showed burnt marks in one of the two electrical tabs,
so it was easy to identify the problem area.
Kenny Mims wrote:
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