[modern] BFM weirdities (second post, first vanished into the server?)

Happy holidays listers, and thanks for the replies I
got on the
intermittant ‘brake pad low’ warning of a while back.
(That has been
tentatively diagnosed as a loose connection somewhere,
as there’s no sign
of ‘ridging’ from the rotors, and the warning went
away after a few brief
appearances and has not returned).
Did a run down to Seattle and back and the car
behaved well all the way up
to 150 km/h (as fast as I was willing to take it on
‘S’ rated tires, and
with a Uniden LRD937 radar detector of as-yet
unverified capability).
During the trip I did diagnose a problem that’s been
appearing slowly over
the last month - failing left rear turn signal when
brakes are applied.
Bulbs are all OK, contacts clean, and WD40 applied.
Since this sounded like
a BFM problem, I proceeded to delve into its depths
after reading the
archives. (Somebody should tell us poor newbies that
the hard part of that
is getting the cover off the module!)
Inside, relays looked ok but I lightly WD-40’d them
and cleaned to
contacts gently with a jewler’s screwdriver. Removed
both circut boards,
and found minor traces of corrosion on a few of the
main board contacts. I
cleaned these gently and examined the actual solder
joints, all of which
looked fine… reassembled, tested, took for 30 minute
test drive… all
This morning… entire unit is dead. No break,
parking, or turn signal
lights at all. Immediate suspiscion was the two-lead
ground line, so I
pulled that bolt again, re-cleaned all 3 of the
connections grounded there,
and reattached. No good.
Pulled out BFM again, re-opened, and decided to go
with the list’s
collective historical solution- I re-flowed all even
remotely questionable
solder joints, using a pencil iron, and carefully
cleaned and examined the
boards for any cross-lead shorts.
BFM works… then stops. A sharp rap on the case
makes it all happy
again, for an intermittant (but too short) period.
I’m guessing from this it’s a mechanical problem…
one of the actual
relays is sticking (just like my ABS Overvolts relay,
but it’s another
story and works 90% of the time… further down the
‘to do’ list).
Pulled it apart yet again, wiggled and poked
at all the relays, lightly sanded the contact points
between main and sub-board, re-flowed solder on yet
more contacts, and re-installed. Result: now, the VCM
displays a ‘Bulb Failure’ if the brakes are applied,
and the dash left-turn indicator will flash at double
the normal rate if a left-turn is being signalled at
the same time, but externally the lights all work (at
least for now). Anyone
have any suggestions/ insight as to how to perk up the
relays, or if that’s
even the likely cause?
If all else fails I’ll “just” shell out the cash for
a new module, but I’d
rather not if it’s fixable, and it certainly looks

John Brunstein
'87 XJ40, 188,000 km, Moorland Green
'00 Honda SK50 Dio 5500 km__________________________________________________
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