[TR] TR250 LED tail light problem

Wed Nov 13 08:20:10 MST 2019

Doesn't Moss sell tail light bulb holders with grounding tabs?

https://mossmotors.com/bulb-holder-turn-reverse

Dave

[image: image.png]

On Wed, Nov 13, 2019 at 12:15 AM Brian Kemp <bk13 at earthlink.net> wrote:

> I seem to remember once upon a time, somebody made a light socket with a
> ground wire or a ground tab.  I looked a few months ago for my GT6, but
> couldn't find it at the usual vendors.  I imagine you could add a ground
> wire, but some of my sockets are pretty bad, so I was looking for new ones
> that already had the wire.
>
> On my TR6, I did have a socket that didn't conduct well to ground.  The
> problem was the connection between the metal base and the metal fingers.  I
> just hit the area with a wire brush in the Dremel then soldered the two
> bits together and it fixed that problem.
>
> Brian
>
> On 11/12/2019 2:38 PM, Roger Elliott wrote:
>
> I decided to give up on the issue.
>
> There did not seem to be much of a voltage drop across the battery - about
> .05 volts as near as I could make out.  It's possible that either the meter
> or myself were not quick enough to read accurately.
>
> As far as I could tell there is not a ground terminal on the sockets.
> There was about .009 volts between the lamp housing and the battery.  I did
> run additional wires from the lamp housing to a ground (to the tank
> mounting bolts).
>
> The brake/tail lights still varied with the turn signals, in opposition,
> got brighter when the turn signals were off.
>
> Tested the lights with regular brake lights instead of LEDs. I noticed the
> brake/tail lights still varied with the turn signals.  This is when I
> decided to give up and just live with it.
>
> Oh, the third brake light that I have wired in - power from the brake
> lights and grounded to the body flash when ever the brake lights and turn
> signals are on (like the brake/tail lights in opposition.
>
> Thanks for your help.
> Roger
> On 11/3/2019 4:37 PM, Randall wrote:
>
> Yes, that’s the idea.  You want all the lights on (including turn signals)
> during this test.
>
>
>
> What you’re looking at is how much voltage drop there is through the
> ground path.
>
>
>
> -- Randall
>
>
>
> *From: *Roger Elliott <elliottr at rmi.net>
> *Sent: *Sunday, November 3, 2019 1:26 PM
> *To: *triumphs at autox.team.net
> *Subject: *Re: [TR] TR250 LED tail light problem
>
>
>
> HI Randall,
>
> Thanks for the information and the tests.
>
> I just want to check something on the tests since my electrical trouble
> shooting ability is very limited.
>
> This section is also done with the lights on, right?:
>
> 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.
>
>
> Thanks,
> Roger
>
>
>
> On 11/2/19 4:07 PM, Randall wrote:
>
> 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.
>
>
>
> 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.)
>
>
>
> 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.
>
>
>
> 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.
>
>
>
> 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.
>
>
>
> 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.
>
>
>
> -- Randall
>
>
>
> *From: *Roger Elliott <elliottr at rmi.net>
> *Sent: *Friday, November 1, 2019 12:50 PM
> *To: *triumphs at autox.team.net
> *Subject: *[TR] TR250 LED tail light problem
>
>
>
> Here's the problem.  When the tail lights are on and I use the flasher,
>
> the tail/brake lights flicker with the flasher.  They don't go on and
>
> off but the get brighter and dimmer.  When the third brake light is
>
> hooked up it does the same thing.
>
>
>
>
>
>
>
>
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