Does the ignition warning light glow when first turning on the ignition and
go out when the engine is started and revved to at least 1000rpm? It
should. If not the warning lights acts as a 'pump primer' to the alternator
and although IME used alternatorsd will start to charge withoutit but only
when revved to 3k or so a brand-new alternator may not.
Is this the current in the main battery cable with everything switched off?
It should be no more than micro-amps from the normal slight reverse leakage
from the alternator diodes, nothing at all with the alternator (and clock,
radio memory, alarm) unplugged. Milli-amps or more will drain the battery
over time. The bottom fuse (purple) controls things like the horns, courtesy
lights and factory clock. If you still have current with the bottom fuse
and the alternator unplugged you will have to start disconnecting browns to
track it down.
BTW, measuring current can be tricky because cars can draw much more than
most hobbyist/auto multi-meters can take. At best it will blow an internal
fuse, at worst wreck the instrument. To check for leakage currents I use an
analogue voltmeter on its 20v scale, this will show when very small currents
in the order of microamps are flowing, but if there is a major short will
not allow large currents to flow.
----- Original Message -----
From: "Lysander Meath Baker" <lysander@meathbaker.org>
To: "MG List" <mgs@autox.team.net>
Sent: Thursday, April 03, 2003 11:47 PM
Subject: FW: Eletrical Gremlins
> Just bought a voltmeter and found that I've only got 12v on a brown when
> idling at 2000rpm
>
> I had a new alternator fitted in October, so it *should* be OK.
>
> I also checked the current (as advised by the instructions that came with
> the multimeter) and I get a pulsing current (that seems to match the
ticking
> clock) of 20mA. Removing fuses 1 to 3 made no difference, but removing the
> 4th fuse from the top reduces the current to a steady 15mA.
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