This deja vu.
The brown/yellow primer/indicator wire, which is presumably what you mean by
the 'tickler' wire, should NOT be hot when the ignition is off and the engine
is not running. If it is then either the alternator diodes have blown or
there is a serious wiring fault. Whilst a blocking diode may reduce (there
will still be some) the discharge it is only covering up the real problem
which could burn the loom or even destroy the car through fire, even when
parked. If such a diode *was* put there to hide a problem, and it has shorted
out then it *will* cause the battery to flatten while parked.
It is easy to determine whether the alt or the wiring is the problem, just
unplug the alt. If the brown/yellow is still showing 12v it is a wiring
problem, if not it is an alternator problem. There is one other possibility
and that is the ignition switch is not disconnecting 12v from the white wire
when the ignition is off. Normally this would prevent switching off the
engine, but if you have a working anti-runon system it is this which is
stopping the engine even though the ignition is still live. Again this is
easy to check, just measure the voltage on the white side of the warning light
and again on the brown/yellow. Which ever has the higher voltage wrt to
ground is the source.
Any diode that is present in the brown/yellow is NOT a factory component but
is usually a PO frig to overcome problems with the anti-runon system that
allow the engine to continue to run after the ignition is switched off. Any
such diode should NOT be a zener diode anyway as, depending on its 'breakdown'
voltage, that would defeat the object, it would be a conventional 'blocking'
diode, and this is regardless whether it has been inserted to cover up an
anti-runon system problem or the much more serious wiring or alternator
problem.
Please don't fit another diode, investigate and fix the real problem.
PaulH.
----- Original Message -----
From: Aeseeyou@aol.com
To: mgs@autox.team.net
Cc: mg-mgb@yahoogroups.com
Sent: Tuesday, October 28, 2003 10:51 PM
Subject: [MG-MGB] Help! Something is killing my new Battery
A diode that I didn't know was even there, had to be spliced
back onto the new "tickler" wire (which is always "hot") ... so that the hot
"tickler"
lead didn't bleed the battery by dead by letting it short itself out.
Trouble
is, even though I eventually realized that the "zenar" diode had to be
replaced,
and I did reinstall the same diode that was on the alternator that I'd
removed. Question: If the old Diode is shorted or burned out, would this
cause the
brand new battery to go dead overnight!!
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