LED Gremlins

[Origin7]

I am converting the halogen indicator lights on my older Cat to LED. I am wondering if anyone else has encountered the issue I am having. 

 

I did the following:

 

1. Installed LED bulbs in the front indicators

2. Installed an LED relay

3. Installed rear indicator bulbs

 

So far, so good. Everything worked fine and was super bright. Next, I installed factory Caterham LED front side markers. This is when the gremlins arrived. Now, all 6 are blinking together, instead of 3 right or 3 left. Voltage had to be backfeeding between the left and right sides somewhere in the circuit. The two common components are the relay and the dash light. The relay tested fine, so I removed the bulb on the dash. Sure enough, this fixed it. So I need a more permanent solution. My dash indicators are 37 years old. Does anyone know if newer ones will resolve this?

 

Thanks in advance. 

 

    

[7Westfield]

A few years ago, I added a beeper to mine, because the light was right behind the top of the steering wheel. Had the same issue

Fixed it with a pair of diodes feeding the buzzer, one from each side

 

 

[Scott_]

I think @westfield is right.   Your indicator bulb is creating a back-feed path between the two circuits so the diodes should stop that.

 

Scott.

[Origin7]

Thanks! Diodes are on order. 

 

Mike

[Origin7]

I can confirm @Scott_ and @7Westfield are correct. The diodes did the trick. Thanks to you both. 

 

I also had to change the wiring a bit as well. Previously, the two light socket terminals were connected to the right- and left-side indicator circuits, with no ground. I am not sure if this is typical automotive wiring; I haven't seen it before. Anyway, I changed it so the right and left are now connected to one terminal. The other terminal is now connected to ground.

 

   

[wdb]

Adding diodes to a diode circuit. Strange.

[7Westfield]

I wonder if the 2 sides being connected with no ground was the problem

each was trying to ground thru the other, so everything lit up

[redursidae]

I have a similar issue with mine, but disconnecting the indicator bulb didn't help. I wonder if I disconnected the wrong thing somehow. Anyway, I'm curious about where you bought the resistors from if you can share the source? Looks sorta plug and play?

[Origin7]

2 hours ago, redursidae said:

I have a similar issue with mine, but disconnecting the indicator bulb didn't help. I wonder if I disconnected the wrong thing somehow. Anyway, I'm curious about where you bought the resistors from if you can share the source? Looks sorta plug and play?

 

Here are the ones I bought. You can get no-name brands on Amazon, but I can’t confirm their quality. For this kind of thing, I’d recommend a reputable supplier like DigiKey.

 

https://www.digikey.com/en/products/detail/vishay-general-semiconductor-diodes-division/1N4007-E3-54/754813

 

It’s not exactly plug-and-play, but it’s fairly straightforward if you have some crimp connectors and electrical tape. Heat shrink tubing is preferable if you have it. In the photo, the diodes are covered with heat shrink tubing and crimped into the spade terminal. When you install the diodes, make sure the gray stripe is on the bulb side (they are directional). 

 

[redursidae]

Thanks for the link and explanation. That’ll work for me.