RE: Battling the Dark Side of the Force

["Glenn A. Merrell" <gmerrel@domain.elided>]

Hi Mark,
    First off, go to Radio Shack and buy an inexpensive pocket Digital Volt/Ohm
Meter.  Consider it a fathers day gift from your Stag.  It will be the absolute
best tool you can get for electrical problems.  Read the little manual that
comes with it and don't ever check voltage on the Ohms scale, as this tends to
pop the little internal protection fuse and make the meter seem to be
non-functional.  Spend another $25 and get the one with automatic input
protection.  They make one that has only two buttons, ON/OFF and Volts/Ohms for
those that can't make heads or tails of all the buttons and switch positions.
Get a DIGITAL volt/ohm meter because it automatically switches polarity +/- for
you in the voltage scales, and most newer ones are AUTO-RANGING, meaning that
they will automatically switch to the correct voltage range when sencing the
voltage.  Some will also autorange between Direct Current (DC) and Alternating
Current (AC), handy even if you are the most experienced technicial or
engineer.

Next, get Tim Buja's great little Stag Electrical reference article from the
VTR website at http://www.vtr.org/Stag/Stag-elec.html
This article has all the colors and color combinations used in USA Stag
harnesses.  This is important because the harnesses between the USA and other
markets are different in ways that will have you chasing the wild electrical
goose.

Then, after learning what the difference between "Battery Control" (always ON
voltage) and "Ignition Control" (voltage ON only in key positions I and II of
the ignition) circuits and related colors, use the meter to check for voltages
always from the wire to a chassis point, or the nearest black wire.  An
alligator clip on the black meter lead connected to a chassis bolt or black
ground wire makes it easier to deal with just the red  meter lead for chasing
voltage.

The purple wire is hot from the battery through fuse 1-2.  If you connect the
positive lead (usually red) to the wire and the negative lead (usually black)
to the chassis or wire harness black wire, the meter should display about
+12.0VDC +/- a volt depending on your battery condition.

Troubleshooting electrical problems is usually a matter of working back from
the point where there is no voltage to the point where there is voltage.
Continuity (ohms) can be a good troubleshooting tool also if the meter has a
built audio tone when a short is detected, just make sure you disconnect the
battery BEFORE checking continuity.   Watch for the fuse that looks okay thru
the glass, but is separated inside either end of the cap, a frequent
intermittant electrical problem area.  It may check okay on  continuity, but
with voltage applied will open.  Also, the rivets that hold the fuse clips to
the fuse block loosen, corrode and cause a lost or poor connection, and push
connectors between wire harnesses also get corroded.  I've not seen an
connector vibrate apart, usually they are impossible to separate withour
breaking at least 3-4 knuckles, or the connector insulation.  Another common
problem when restoring is that the battery ground strap may not get connected
properly to a good clean chasssis point, and back onto the engine block.  There
are other areas where several black ground wires come together to be attached
onto a bolt to the chassis that become broken or corroded.

The purple wire and Purple/white wires are described in the Stag Electric-kery,
along with the Red/black lead, both of which are voltage.  This might explain
why the stereo did not work, If you connected the RB wire to ground, you popped
fuse 5-6 when it connected to chassis ground through the radio case.

Hope this helps.

My far from humble opinion FWIW, yours for speculation.

Regards,
Glenn  Merrell
Triumph Stag Register USA VP
*J*O*I*N**Y*O*U*R**L*O*C*A*L**T*R*I*U*M*P*H**C*L*U*B**T*O*D*A*Y*
*Member of:
*VTR, RMTC, TSC USA, TSR, SOC
*73*S*T*A*G************************************************************

Help:

>
> Sat down last night to start the stereo installation project.  I located a
> purple and purple with white wire to which were attached a red and black
> lead, suggesting negative earth and "hot".  When I attached to these to see
> if the unit had power, I got nothing.  Additionally, my interior lights
> (switch above the left window lift switch) now do not light.  I consulted
> the wiring diagram, but I have to admit that I could not make hide nor hair
> of it.....The interior lights have been persnickety (tech term) of late,
> sometimes lighting other times not....so I am not sure if my  fiddling with
> the purple, purple with white stripe leads had anything to do with the
> lights not lighting......
>
> Please help me summon the good side of the force and vanquish the prince of
> darkness (Lucas-and I don't mean George)
>
> Mark D. Weir