Automotive lightning circuit issue - diode leakage?

Thread Starter

djreiswig

Joined Aug 8, 2008
108
I'm working on adding some lights to a mini car for a friend. I'm adding turn signals, parking lights and brake lights.
It all works pretty good except I'm having a problem with the parking lights and the turn signals. When the turn signal is flashing on one side and the parking lights are on, the parking light on the opposite side flashes dim. I believe it is due to current leaking through the diode. I'm wondering if there is a simple way to deal with this.
I have attached a schematic as well as the trailer module that I'm using to make the single led rear lights work as park, turn, stop.
I was going to upload a video, but it won't let me.
Any ideas?IMG_20200829_094643263.jpgIMG_20200829_094712028.jpg
 

sagor

Joined Mar 10, 2019
325
Your schematic shows 6 wires to/from the trailer controller, but it has 8 in/out wires, so something is missing? I doubt it is any diode leakage, especially with 2.2k resistors inline with them.
The flasher must have some ground return in order for it to run the flash circuit, but you only show +12V input and output to the lights via a switch. Grounding thru LEDs (lights) may not be enough to properly trigger the flasher? I would check the ground connections for each LED, make sure they are all tied together.

Good luck
 

Thread Starter

djreiswig

Joined Aug 8, 2008
108
Thanks for the reply.
The extra wires on the controller are for the tail lights. According to the instructions, these wires simply pass through the controller for easier wiring.
There is one other ground wire I don't have connected. I will try connecting the second ground wire, but I expect that it simply passes through as well.
The flasher module only has 2 pins, no ground. It makes the lights flash correctly. The issue is with the park lights.
The ground wires from all LEDs are run directly to the battery.
 

Thread Starter

djreiswig

Joined Aug 8, 2008
108
I have the grounds from the pairs of LEDs connected together and run to the battery through a single wire. I'm wondering if something is back feeding through the ground. I'm going to try splitting them and running separate wires to the battery.
I'm confused why the opposite signal light doesn't flash at all when I have the parking lights turned off, but flashes slightly brighter than the parking light when they are on. The parking lights work as expected with the signals off.
 
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Thread Starter

djreiswig

Joined Aug 8, 2008
108
I unhooked all but one rear light. When I turn the opposite signal on, the remaining light flashes dim when the park lights are on. If I disconnect the module and connect the rear lights to the front lights all work correctly, so it must be something in the module. I'm wondering if anybody knows what I can replace the module with to get the rear signals to work correctly with the brake lights. So when the brake lights and signal lights are on, the signal takes precedence.
 

Thread Starter

djreiswig

Joined Aug 8, 2008
108
Okay, I figured out a fix. I added a diode on each wire from the module to the led. This keeps the park light signal from going to the module, but allows the module to power the led in signal mode. I'm guessing the lower voltage from the resistor was confusing the module. Anyhow, it seems to be working now.
 
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