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Electrical Gremlins. Bad Alt? Grounds? Ideas?


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My car is a 76. I have an e21 AL116x Bosch alternator.  I got a new set of LED headlights.  Install was easy, plug and play.  Turned the ignition to the on position and the lights worked perfectly.  Started the car and the lights jumped to hi beams.  Turn it off and they work normally hi and lo beams.  Started the car and played around with the fuses, relays, and after a few minutes, the lights switched to low beams and worked perfectly, low and high worked when switched.   Called Vintage Car LEDs where I got the lights and they said while not common, it’s happened a few times and the when the LED controller senses low voltage it fail safes to the high beams.   He thought it could be bad grounds.  So what happens now is when you start the car, when you turn on the lights, high beams are on no matter what you do with the high beam switch. After the car is on for a few minutes the lights flicker, and then go to low beams then operate normally from then on.  If this was a ground issue, I would think it would be constant, not just when the car is first started and for a few minutes.  I would also think it would happen when the engine is running or not.  When engine isn’t running and it’s on battery, it’s fine...when the engine is running and it’s on alternator, low voltage for a while then the voltage builds?  I have a VDO voltmeter and it’s reads about 13-14 volts at all times.  Maybe relay?  Bad or old relay?  Voltage regulator? Alternator?  One other thing that’s odd, when driving and it’s in high beam only mode, if I hit a bump it flickers like there is a voltage jump when hitting bumps.  Would love some ideas on where to start to diagnose the gremlins.  

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JR, If you have the stock '76 wiring and relays, the LOW beam lights are turned on by the LOW BEAM RELAY pin #85 being grounded through the HIGH BEAM light filament.  Your LED lights do not have

Question: are you using the wiring and relays from previous setup? Did it work before? Having the lights default to high beam makes no sense to me. And if the controller is doing it, why have rel

Another testimonial for how great LED headlights are.... not😉 That diagram is a keeper, Thanks!     No way they are "plug & play"

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Since you have a voltmeter, connect it to battery minus and at the lamp...are you still seeing 13+V? Connect it to Battery minus and the lamp ground connection....do you see anything more than 0.1V?  If you dont see 13V then check relays and fuse condition....if you see more than 0.1V on the ground then its time for cleaning earth points... can't comment on 'smart' lamps reacting to voltage - honestly that sounds unlikely that the lamp has some voltage sensing circuit.

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Question: are you using the wiring and relays from previous setup? Did it work before?

Having the lights default to high beam makes no sense to me. And if the controller is doing it, why have relays?

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its a 76 and it has the factory wiring.  working fine before.  new lights are plug and play and connect directly to the existing connector.  

6 hours ago, dlacey said:

Since you have a voltmeter, connect it to battery minus and at the lamp...are you still seeing 13+V? Connect it to Battery minus and the lamp ground connection....do you see anything more than 0.1V?  If you dont see 13V then check relays and fuse condition....if you see more than 0.1V on the ground then its time for cleaning earth points... can't comment on 'smart' lamps reacting to voltage - honestly that sounds unlikely that the lamp has some voltage sensing circuit.

 

will try those things.

 

I guess another basic question....

 

is it common for the voltage to fluctuate (at idle and various RPM's ) as the car gets warmer?

 

Since the issue only happens when engine is running...maybe check alternator connections...which I did...but check again?

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JR,

If you have the stock '76 wiring and relays, the LOW beam lights are turned on by the LOW BEAM RELAY pin #85 being grounded through the HIGH BEAM light filament.  Your LED lights do not have a filament, so there is no connection to ground...resulting in the high beams always on.

 

Here is a sketch so you can trace the problem.  Hope it helps.

 

John

 

Fuses 9 - 11.jpg

 

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Another testimonial for how great LED headlights are.... not😉

That diagram is a keeper, Thanks!

 

 

No way they are "plug & play"

Edited by tech71
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3 hours ago, jrhone said:

 

 

I guess another basic question....

 

is it common for the voltage to fluctuate (at idle and various RPM's ) as the car gets warmer?

 

Since the issue only happens when engine is running...maybe check alternator connections...which I did...but check again?

It might vary a bit if the alternator is topping up the battery after starting. But it should be high 13s/low14s once things settle down.

Do you have the little brown ground wire between alt and engine? No harm in cleaning ground strap / battery connections.

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4 hours ago, John76 said:

JR,

If you have the stock '76 wiring and relays, the LOW beam lights are turned on by the LOW BEAM RELAY pin #85 being grounded through the HIGH BEAM light filament.  Your LED lights do not have a filament, so there is no connection to ground...resulting in the high beams always on.

 

Here is a sketch so you can trace the problem.  Hope it helps.

 

John

 

Fuses 9 - 11.jpg

 


So question. Why does it work normally when the engine isnt running?  Why does it work normally after the engine has bern running 5 minutes?  
 

these are not just led bulbs plugged in. Its a whole light system designed for classic cars.  If that matters.  

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2 hours ago, Hans said:

It might vary a bit if the alternator is topping up the battery after starting. But it should be high 13s/low14s once things settle down.

Do you have the little brown ground wire between alt and engine? No harm in cleaning ground strap / battery connections.


yes i have the ground between alt and engine.  Will check and clean grounds.  

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Do your LED headlights use the same 3-prong plug used on the incandescent bulbs?

Check the ground (brown) wires to each bulb.

Do you get 12v on the Yellow/black (left low beam) and Yellow/blue (right low beam) when the lights are on?

You should have 0v on the Yellow/xx wires when the high beams are on (or the high-beam flasher).

You should have 12v on the White/violet wires (R & L high beams) only with the high beam switch is activated.

Also, check that your relays are operating correctly. LED lights do not work like "normal" bulbs...they are sensitive to correct polarity.

You might have to bypass the relays altogether.......but that's waaaaay above my pay-grade.

 

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So the system i bought was a led bulb with a controller box with the 3 prong connector.  Plug that into the socket on the car for the headlights and go.   Designed for classic cars.  So i had zero wiring to do and it was designed that way. Lots of these lights sold to the vw and porsche community as well as american hot rods.  So not just some random bulb but a bulb, lens and it all plugs in into the stock harness.  Will check the voltage when then key is but engine off and when the engine is on.  When the key is on and the engine is off its perfect.  Its just for 5 minutes after first starting the car that its high beam inly and then it starts to operate normally.  

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8 hours ago, tech71 said:

Another testimonial for how great LED headlights are.... not😉

That diagram is a keeper, Thanks!

No way they are "plug & play"

these symptoms are in no way representative of using LED  bulbs.

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22 hours ago, jrhone said:

My car is a 76. I have an e21 AL116x Bosch alternator.  I got a new set of LED headlights.  Install was easy, plug and play.  Turned the ignition to the on position and the lights worked perfectly.  Started the car and the lights jumped to hi beams.  Turn it off and they work normally hi and lo beams.  Started the car and played around with the fuses, relays, and after a few minutes, the lights switched to low beams and worked perfectly, low and high worked when switched.   Called Vintage Car LEDs where I got the lights and they said while not common, it’s happened a few times and the when the LED controller senses low voltage it fail safes to the high beams.   He thought it could be bad grounds.  So what happens now is when you start the car, when you turn on the lights, high beams are on no matter what you do with the high beam switch. After the car is on for a few minutes the lights flicker, and then go to low beams then operate normally from then on.  If this was a ground issue, I would think it would be constant, not just when the car is first started and for a few minutes.  I would also think it would happen when the engine is running or not.  When engine isn’t running and it’s on battery, it’s fine...when the engine is running and it’s on alternator, low voltage for a while then the voltage builds?  I have a VDO voltmeter and it’s reads about 13-14 volts at all times.  Maybe relay?  Bad or old relay?  Voltage regulator? Alternator?  One other thing that’s odd, when driving and it’s in high beam only mode, if I hit a bump it flickers like there is a voltage jump when hitting bumps.  Would love some ideas on where to start to diagnose the gremlins.  

i am presuming you are using some kind of H4 setup since that is the 02 lamp requirement. I have these in my 02 and have not experienced any of these problems.  I don't even remember who provided my H4 setup, but I can check that out if it would be helpful. You should probably bypass the 02 headlamp relays and use them only for switching a more modern set of relays, provided by most HID or LED lamp suppliers. You may also want to try a different supplier for your H4 system. This really doesn't seem like an electrical system (on the 02 side ) problem. The flickering you are observing sounds more like a poor connection in the circuit(s) than a voltage jump.

Edited by Chris_B
corrected typos
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JR, the question to ask the LED lamp system supplier:  "should I be using this system with the OEM relays in the factory wiring harness, or should I bypass the relays and connect the LED lamps directly to the headlight and dimmer switch?"  

 

From John76's comments and diagram, the low beam relay may not be triggered by the high beam that's grounded through its filament, since the LED has no continuity between its + and - terminals when it's not energized.  

 

mike

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9 hours ago, Mike Self said:

JR, the question to ask the LED lamp system supplier:  "should I be using this system with the OEM relays in the factory wiring harness, or should I bypass the relays and connect the LED lamps directly to the headlight and dimmer switch?"  

 

From John76's comments and diagram, the low beam relay may not be triggered by the high beam that's grounded through its filament, since the LED has no continuity between its + and - terminals when it's not energized.  

 

mike

Out of curiosity, why would they ground the relay through the bulb? And I know this is a dumb question, but wouldn't that power the bulb? Be gentle.

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