shelby tail light sequential 12v issue

[Andreas1973MustangMach1]

Hi pros

I installed in my mustang the shelby taillight from a 67 mustang including the the shelby sequential kit.

In austria the turnlight have to shine in orange/yellow so thats why i tried to install yellow leds.

The problem is i dont become 12v from my cables so that the first led shines normal the secound low and the third not. I messed it and its like 12v - ~8v - ~4v

With normal lamps it works fine but the last lamp also would shine a little lower.

Now i look for a way to get constant 12v or a way that normal lamps shine orange threw the red lens

Thanks guys

Andreas

 

[MechEng]

The problem that you have here is that the bulbs are wires in series with each other it sounds like. Without a schematic it's hard to know for sure. But you're right on, as the 12v goes across each LED it experiences a voltage drop (of an amount equal to the forward voltage of the LED) so that the next LED has less voltage to work on. You really need them to be wired in parallel so that they are each fed 12V directly. But this is going to be a hard modification to suggest without better knowledge of how the circuit works.

A quick internet search suggests that the circuit was borrowed for the 1966 thunderbird, which means that this:

http://www.allfordmustangs.com/forums/attachments/classic-tech/124297d1299765915-1967-mustang-coupe-converting-sequential-taillights-old-school-version-66tbirdext.jpg

Is the circuit for the tail lights. Looking at that, it seems as though the lights should already be in parallel which would remove this problem.

I think we need more information from you about exactly what you're using to better understand the problem and try to help.

 

[will e]

Hi, and some pictures.

 

[Andreas1973MustangMach1]

Hi guys

THanks for the answer.

I will add some pictures today.

Yea the serie connection was my first idea too.

So that i tried it yesterday in parrallel. But the shined all together at the same time and not sequential.

But i had less time to be 100% sure to done it right. Will try it today. What i have seen that the relay of an led sequential kit is much bigger thwn the relay of an lamp led sequential kit.

I bought mine from mustang unlimited. I will add it too.

Regards

ANdreas


The next idea was to add a secound circle to the leds with resistors to have ~9v and when the lower signal arrives the leds it should have 12v like in the truck batteries. Or will i burn the cables?

Im not really good in electrical works.

I added a schematic but like i said no idea if this is correct.


The only different to my circle like on the schematic is that the leds are grounded together with 1single cable but im not sure if it makes the different

 

[will e]

I do not understand your schematic.

The ground wire all foing to the same place shouldn't be an issue, it would also indicate you have them run in parallel, not series.

What 'triggers' the next light in line? Also, if you put a regular bulb in the 'first' socket does the third one then light up when it is supposed to?

What did you buy from Mustang unlimited?

 

[MechEng]

Hi guys

THanks for the answer.

I will add some pictures today.

Yea the serie connection was my first idea too.

So that i tried it yesterday in parrallel. But the shined all together at the same time and not sequential.

But i had less time to be 100% sure to done it right. Will try it today. What i have seen that the relay of an led sequential kit is much bigger thwn the relay of an lamp led sequential kit.

I bought mine from mustang unlimited. I will add it too.

Regards

ANdreas


The next idea was to add a secound circle to the leds with resistors to have ~9v and when the lower signal arrives the leds it should have 12v like in the truck batteries. Or will i burn the cables?

Im not really good in electrical works.

I added a schematic but like i said no idea if this is correct.


The only different to my circle like on the schematic is that the leds are grounded together with 1single cable but im not sure if it makes the different

Ideally you'd want your schematic to end up looking like this:

Where J1, J2, and J3 are the control signals for the tail light, and K1, K2, and K3, are the relays switching each light on and off. Resistors R1, R2, and R3, need to be sized appropriately to limit the current flowing through each LED. To calculate that resistor value the equation is as follows:

R = (V1 - V2) / I

Where:

V1 = Power Supply Voltage (In this case 12V)

V2 = LED voltage

I = LED current (usually 20mA which is .02A)

This is an important step as applying 12V directly to most LEDs will cause them to fail in a short amount of time.

I hope this helps!

 

[Andreas1973MustangMach1]

Ok i took a look at my cables yesterday. My schematic was wrong. There comes 3 different wires from the sequential condensator or what ever this is.

Here is the kit i bought. Only what is missing is the relay with 3 wires


Picture