ryen74
I replaced the bulb style '38 Ford teardrop tail lights that came on my '74 SB when I bought it with LED ones of the same style. The problem is now that they seem to only work when they feel like it. I replaced them because the other ones did not light up that bright. Do I need to get resistors because the LEDs take less electricity? Where would I put the resistor?
Ryen
"Arizona dreamin'"
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68autobug
Hi
If the Light Emitting Diodes LEDs do light up sometimes
then over voltage is NOT the problem
as over voltage will Burn them out... instantly
 
I would say You have an earthing/grounding problem..
 
If You take the light assembly off the fender
they should stay alight
if they are grounded by a wire...
if they go off.. they need a grounding wire...
All My lights have ground wires
so they don't need to be grounded to work
 
but - I rewired My car.. 
 
and I always add ground wires to any VW I work on...
if the wiring is missing...
 
also, if the LEDs are made to work on a car they would already have a resistor so they would work at 12V-14v
 
I hope this helps
 
LEE
 
http://community.webshots.com/user/vw68autobug
 
68AutoBug - helping keep air cooled Volkswagens alive in Australia & around the World -

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ryen74
I'll check it out. Thank you.
Ryen
"Arizona dreamin'"
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ryen74
Still not working. I have checked the ground. If I out a resistor in, the current will go down and that may fix the problem. What ohm should I try?
Ryen
"Arizona dreamin'"
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pa_trick
Ryen;

Get yourself a multimeter and read the DC voltage that you are getting at the plug for the light. It should read the same voltage as the battery does (whether the car is running or not). The next step is to see if the voltage stays the same when your LEDs are not working.

I suspect it is a connection issue. Some of those less expensive LEDs have cheap circuit boards with them which effect the quality of the connection.
Patrick
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74 Super Sun Bug (the partner's)
71 Super Cal Looker (mine)
the "Shade tree mech" for both...
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ryen74
Where do I check the DC voltage at?
Ryen
"Arizona dreamin'"
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pa_trick
Check the DC voltage at the point where you connected the LEDs to the car's electrical system.

If you have two wires, test between them and see what voltage you are getting.

If you only have one wire, test between that and the a piece of bare metal on the frame.

It just occurred to me that you just might be having a poor ground so make sure that you have a good clean connection on the ground side of the wiring. Normally this where one of the wire is screwed into the body. frequently rust at this point will impact the ground connection

Patrick
------------(0\ /0)-------------
74 Super Sun Bug (the partner's)
71 Super Cal Looker (mine)
the "Shade tree mech" for both...
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68autobug

pa_trick wrote:
Check the DC voltage at the point where you connected the LEDs to the car's electrical system.
If you have two wires, test between them and see what voltage you are getting.
If you only have one wire, test between that and the a piece of bare metal on the frame.

It just occurred to me that you just might be having a poor ground so make sure that you have a good clean connection on the ground side of the wiring. Normally this where one of the wire is screwed into the body. frequently rust at this point will impact the ground connection


this may also be the problem with your old Dull lamps..
I gave my Son a pair of stop tail lamp LED bulbs as they
weren't bright enough for Me...
but there are new ones out Now with LEDs facing outwards too..

but I did add grounding wires to his tail lamps..
when i wired them up..

LEDs are very low voltage items, if 12v is put thru them they will
burn out instantly...  otherwise they will last just about forever..

cheers

LEE


68AutoBug - helping keep air cooled Volkswagens alive in Australia & around the World -

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68autobug
 
I just thought
its probably best to get the original bulbs working
nice and bright...
then plugging in the LEDs..
 
cheers
 
LEE
 

68AutoBug - helping keep air cooled Volkswagens alive in Australia & around the World -

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pa_trick
I agree with Lee, get the original lights working right first, then plug in the LEDs.

If you have another car, plug the LEDs into to it and test them. That will tell you if the problem is with the LEDs or the bug.
Patrick
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74 Super Sun Bug (the partner's)
71 Super Cal Looker (mine)
the "Shade tree mech" for both...
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ryen74
Alvin did not have original bulbs when I got him. He had '38 Ford replica tear drops with 1157 bulbs in them. They stunk so I got the '38 Ford LED lights to replace them. The lights aren't bulb plug in LEDs. They are wired into the stock wiring. I checked the voltage and it ranges from 9-12 depending on the wire.
Ryen

Ryen
"Arizona dreamin'"
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pa_trick
Quote:
I checked the voltage and it ranges from 9-12 depending on the wire.


You are testing where you connected them to the standard wiring harness? How many wires do you have on the harness and how many connections for the LEDs? Identify which wire is the ground. If you do not have one, put one in it will save a lot of time.

Then draw a picture of the other wires and take a voltage reading between each of them to the ground wire in the following states:
1. Ignition on (no headlights, brakes, or turn signals)
2. With headlights only
3. With Brakes only
4. With turn signals only

Each time marking the results on your drawing. This should give you a pretty good picture of what is happening on the supply side.

On the LED side (with a ground wire connected), try applying 12VDC (jumper from battery would be best) to each of the connections and see if you  get what you are expecting. If you a jumping from the battery, the turn-signal will not blink, but will be on normal.

The 9VDC might be the norm for tail lights with 12VDC for turn signal and brakes, but I am not sure on that. Check what the documentation on the LEDs tells you on that.
Patrick
------------(0\ /0)-------------
74 Super Sun Bug (the partner's)
71 Super Cal Looker (mine)
the "Shade tree mech" for both...
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