<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
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--></style></head><body lang=EN-US link=blue vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Yes, that’s the idea. You want all the lights on (including turn signals) during this test.</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>What you’re looking at is how much voltage drop there is through the ground path.</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><div style='mso-element:para-border-div;border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='border:none;padding:0in'><b>From: </b><a href="mailto:elliottr@rmi.net">Roger Elliott</a><br><b>Sent: </b>Sunday, November 3, 2019 1:26 PM<br><b>To: </b><a href="mailto:triumphs@autox.team.net">triumphs@autox.team.net</a><br><b>Subject: </b>Re: [TR] TR250 LED tail light problem</p></div><p class=MsoNormal><o:p> </o:p></p><p><span style='font-size:10.0pt'>HI Randall,</span></p><p><span style='font-size:10.0pt'>Thanks for the information and the tests.</span></p><p><span style='font-size:10.0pt'>I just want to check something on the tests since my electrical trouble shooting ability is very limited.</span></p><p><span style='font-size:10.0pt'>This section is also done with the lights on, right?: </span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>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.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <br>Thanks,<br>Roger<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><o:p> </o:p></p><div><p class=MsoNormal>On 11/2/19 4:07 PM, Randall wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><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.<o:p></o:p></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.)<o:p></o:p></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.<o:p></o:p></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.<o:p></o:p></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. <o:p></o:p></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.<o:p></o:p></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><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b>From: </b><a href="mailto:elliottr@rmi.net">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">triumphs@autox.team.net</a><br><b>Subject: </b>[TR] TR250 LED tail light problem<o:p></o:p></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, <o:p></o:p></p><p class=MsoNormal>the tail/brake lights flicker with the flasher. They don't go on and <o:p></o:p></p><p class=MsoNormal>off but the get brighter and dimmer. When the third brake light is <o:p></o:p></p><p class=MsoNormal>hooked up it does the same thing.<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p></blockquote><p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:.5in;margin-bottom:5.0pt;margin-left:.5in'> <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>