Re: Weird Light interaction

[ti@bazooka.amb.org (Ti Kan)]

Autobahn01@aol.com writes:
> In a message dated 96-02-29 18:41:40 EST, Luke.VINOGRADOV@ENG.monash.edu.au
> (Luke D. Vinogradov) writes:
> 
> >I've got an '81, and my alternator warning light glows dimly when in 
> >reverse, and as my indicators light, it glows a little brighter 
> >on/off/on/off with indicators.  The flasher speed also seems subject 
> >to fluctuations as electricals go on or off e.g. radiator fan.  Is 
> >there an ground leak somewhere?
> >
> >Luke
> 
> Have you tried cleaning up the grounds that bolt to the trunk next to the
> rear lamps? They often build up corrosion on the early series 4000s; also
> inspect your backing plates(that hold the bulbs), if water makes it's way
> into the taillamps corrosion will render the plates junk. Very popular on
> Coupe GT's....
> I'm presuming your car's charging system is up to spec.
> 
> -Hope this helps,
> -Chris Semple
> '84 4000q

I have some experience with this one.  You'll want to check the big cables
first (battery to ground, alternatorr/starter, starter/battery.

My 80 4000 used to have a dimly lit alternator idiot light when I
have the main headlights on, and would flicker in intensity as the
turn signals were operating.  I found out why.  The main power wiring
(some 4000s and coupes, particularly the 5-cyl cars have two wires)
from the battery to the fuse/relay panel connects to the fuse/relay
panel via a large push-on lug.  The actual area of copper contact is not
very large.  Also, the lug is crimped on to the wire, which may also
become corroded and develop resistance.  The amount of electrical
current that this connector must carry is quite large, because
other than the starter, EVERYTHING else goes thorough here.  What this
means is that the connector gets hot due to the resistance and that causes
more resistance.  As you turn on more electrical accessories the
voltage actually drops across the contacts due to the resistance.
And since the alternator idiot light in the dash basically compares the
12 volts it sees from the alternator D+ line and the (now reduced)
power main, it would therefore glow a little.  I "fixed" my car
by removing the factory lug connectors and putting fresh new ones
on, and SOLDERING the lug to the wire instead of just crimping it.
This definitely eliminated the problem, and the volt gauge even reads
higher as a result!

So, you might want to check these connectors for signs of corrosion,
burning or charring...

-Ti
-- 
    ///  Ti Kan                Vorsprung durch Technik
   ///   AMB Research Laboratories, Sunnyvale, CA. USA
  ///    Internet: ti@amb.org
 //////  UUCP:     ...!uunet!bazooka!ti
///      URL:      http://sunsite.unc.edu/~cddb/tikan/