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MGTD: Want Dash Lights on When Headlights On

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Fenner Avatar
Fenner Ferman Wardell
Charlotte, NC, USA   USA
1953 MG TD
New member, first post, having fun with my new 1953 MGTD! My dash lights all work well, though a bit dim. I'll get to that soon, but now my dash lights turn on only when the side lights are lit. I'd like to have them on when the main headlights are on - you know, like when i'm driving at night. How do I accomplish that? Seems I would want to change the 12v power supply from one terminal to another on the headlight switch. Input appreciated.

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ML320X5 Avatar
ML320X5 Stan Y
Tulsa, OK, USA   USA
1952 MG TD
1973 MG MGB
2002 BMW X5
If I recall, you need to hook it up to a different terminal at the back of the headlight switch. One of the terminal got power cutoff when switch rotated to headlight position. Check it with wiring diagram.

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AZTD Avatar
AZTD Silver Member Mike Grogan
Glendale, AZ, USA   USA
1953 MG TD
the wire from the "panel light switch" should be connected to the" T " terminal on the key/light switch



1953 MG TD TD23816



Edited 1 time(s). Last edit at 2019-03-04 08:19 PM by AZTD.

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Fenner Avatar
Fenner Ferman Wardell
Charlotte, NC, USA   USA
1953 MG TD
My dash light switch is already connected to the "T" terminal on the key/light switch just like the wiring diagram here and the one in my service manual both show. But, that's the problem because the dash lights come on only when the side lights do, not when the head lights do (sidelights turn off when headlights turn on). So, it appears I should transfer the dash light switch to the "H" terminal on the key/light switch, right? The "H" terminal has the headlights on it.

As I've been exercising the various lights, I noticed that when the headlights are on, the sidelights turn off, including the taillights. Seems to me the taillights should be on when the headlights are on, right?

Now, what I would really like is for the sidelights and taillights and dash lights to be on together when the headlights are on. Has anyone done that?

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AZTD Avatar
AZTD Silver Member Mike Grogan
Glendale, AZ, USA   USA
1953 MG TD
Mine is wired this way.
I would say your switch is one of the newer switches MOSS put out awhile back. They had problems.
When you turn on the head lights, the marker and tail lights as well as panel lights should still have power.



1953 MG TD TD23816

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ML320X5 Avatar
ML320X5 Stan Y
Tulsa, OK, USA   USA
1952 MG TD
1973 MG MGB
2002 BMW X5
My guess is use the terminals wisely. Never know what was done to it. Main thing is sidemarkers, dash lights and head lights should be all on when head lights are on. Initially my front sidemarkers were all off when head lights were on. Reattached them to a different terminal and both worked as usual.

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zinger356 Avatar
zinger356 Bob Ertzinger
Burlington, IA, USA   USA
Once you find correct terminal for dash and side lights and headlights, bypass the Panel Light Switch and your dash lights will be brighter.
That is unless you need the option to turn off panel lights while driving.
In addition, if not running operational Fog Lights, disconnect hot side of Fog Light switch.
Feed fuel pump wires and/or ignition(coil) wires thru fog light switch for security and trouble shooting. A twist and fuel and spark are disabled.
TD28960

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Tpss Avatar
Tpss Tim Parrott
Stroud, gloucestershire, UK   GBR
1938 MG TA
The panel lights connect to earth through the metal instrument panel. Connect a wire from the back of the panel (use one of the fixing bolts) to an earth point, this may solve your Instrument light problem but may raise another. You possibly have a short circuit from the headlights to the instrument panel.

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ML320X5 Avatar
ML320X5 Stan Y
Tulsa, OK, USA   USA
1952 MG TD
1973 MG MGB
2002 BMW X5
He never mentioned blew fuse tho!
If I recall
"H" for head lights.
"T" for front and back sidemarkers.

Suggestion:
Disconnect panel lights wire from switch first (isolated totally) and see if sidemarkers come on along with head lights. If it does, panel lights circuit may be fishy. If not, switch may be defective. Again who knows what was done previously. Good luck.



Edited 4 time(s). Last edit at 2019-03-05 04:00 PM by ML320X5.

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Fenner Avatar
Fenner Ferman Wardell
Charlotte, NC, USA   USA
1953 MG TD
Great ideas and information, everyone! Thanks for that. I have ordered new key/light and dash potentiometer switches from Moss. Will install this weekend, paying special attention to which wire goes where. The PO took great care replacing the wiring harness and many electrical components, which all look proper to me, so I believe it boils down to the key/light switch. And, yes, I'll disconnect the battery ground before proceeding! Will report back then.

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Fenner Avatar
Fenner Ferman Wardell
Charlotte, NC, USA   USA
1953 MG TD
Voila - problem solved!! Now all of my lights come on along with the headlights. And the sidelights come on by themselves when supposed too. The solution was something so simple that I basically overlooked it. The four red lighting wires were not attached to the "T" terminal but the one next to it: the "L" terminal. "T" is at about 7 o'clock, and "L" is at about 8 o'clock, so just glancing at it made it appear correct. Closer inspection revealed the (now) obvious. Thanks to all for your helpful suggestions.

Now, on to my next project: seat belts.

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MGTF1500 Ardeche France Avatar
MGTF1500 Ardeche France Thierry SUCHIER
TOURNON SUR RHONE, Rhône-Alpes Auvergne, France   FRA
In reply to # 3904013 by Fenner
Now, on to my next project: seat belts.

Fermann,
I await your experience, your explanations impatiently.
Sincerely, Thierry de l'Ardèche, South of France

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