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<p><font size="-1" face="Calibri,sans-serif">HI Randall,<br>
</font></p>
<p><font size="-1" face="Calibri,sans-serif">Thanks for the
information and the tests.<br>
</font></p>
<p><font size="-1" face="Calibri,sans-serif">I just want to check
something on the tests since my electrical trouble shooting
ability is very limited.<br>
</font></p>
<p><font size="-1" face="Calibri,sans-serif">This section is also
done with the lights on, right?: </font><font size="-1"> </font><br>
</p>
<p class="MsoNormal">To check for grounding issues, I suggest
running a wire to the negative battery terminal or negative
starter cable, so you can connect the ground lead of your DMM to
that. Then you can probe at the rear lights, to see how well they
are actually grounded. 0.2 volt is probably acceptable, anything
more than that represents a problem that could be fixed.</p>
<p class="MsoNormal"> <br>
Thanks,<br>
Roger<br>
</p>
<p class="MsoNormal"><br>
</p>
<div class="moz-cite-prefix">On 11/2/19 4:07 PM, Randall wrote:<br>
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<p class="MsoNormal">There may not be a good solution, Roger.
The incandescent turn signals draw a fair amount of current,
which is likely more than the stock alternator can deliver
(along with tail lights and so on) at idle. So it may be that
the battery voltage is dropping from 13+ volts (alternator
supplying all power to car) to 12.6 volts (battery supplying
some of the power) and the LEDs you’re using are sensitive
enough to show the difference in voltage.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">To check, connect a good voltmeter or DMM
to the battery, then watch what it does when the tail lights
and flashers are both on. If I’m right, you’ll see the
battery voltage sag in time with the turn signals. The only
fix would be to convert to a more modern alternator, that can
keep up with the lights at idle. (I’m not certain, but I
think there is a Lester unit that would look and fit the same
as the stock Lucas but give more current across the board.
Check with the Jaguar folks.)</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Another fix might be LEDs that use an
active current source (so are much less sensitive to supply
voltage), but I have no idea where to buy such things. I made
my own using a simple 2-transistor active current limiter.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">To check for grounding issues, I suggest
running a wire to the negative battery terminal or negative
starter cable, so you can connect the ground lead of your DMM
to that. Then you can probe at the rear lights, to see how
well they are actually grounded. 0.2 volt is probably
acceptable, anything more than that represents a problem that
could be fixed.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’m not sure how the TR250 tail lights are
wired. On my TR3, all the rear lamps ground only through
their mounting screws, which go into clip nuts fastened to the
sheet metal. Very insecure, especially if the sheet metal has
a fresh coat of paint. </p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">However, each lamp has a terminal inside
the housing for a ground wire. So, I made up a ground wire
that daisy-chains across all the rear lamp holders, then leads
around the trunk to one of the fuel tank mounting bolts.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">-- Randall<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="border:none;padding:0in"><b>From:
</b><a href="mailto:elliottr@rmi.net" moz-do-not-send="true">Roger
Elliott</a><br>
<b>Sent: </b>Friday, November 1, 2019 12:50 PM<br>
<b>To: </b><a href="mailto:triumphs@autox.team.net"
moz-do-not-send="true">triumphs@autox.team.net</a><br>
<b>Subject: </b>[TR] TR250 LED tail light problem</p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here's the problem. When the tail lights
are on and I use the flasher, </p>
<p class="MsoNormal">the tail/brake lights flicker with the
flasher. They don't go on and </p>
<p class="MsoNormal">off but the get brighter and dimmer. When
the third brake light is </p>
<p class="MsoNormal">hooked up it does the same thing.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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