LED Tail Light Works Fine Except When Truck Is Running

[htech402]

Sorry for yet another LED question but I'm at my wits end on this. I have a 2014 Outdoorsman with factory NON LED light bulbs. I bought a set of LED tail lights that look really great. It was an easy install as so I thought. The light is a whole unit and plugs into the bulb harness (2 one for the flasher and one for the backup light). I got them all hooked up. All the features work (turn signals, brake, hazards, head lights). Everything works great. However, when I turn the vehicle on the brake lights are dim when used (doesn't light up the entire LED area). The turn signal flickers on the activated light and they both sort of flicker dim. Turn on head lights and it does the same thing. When it's shut off everything works flawless. I have no idea what this could be. I have swapped around connectors in the harnesses doesn't help. I even tried keeping the original back up bulbs connected and the LED lights to see if there was an issue there.

Anyone have a clue? It sort of acts like when the truck is on it's getting less voltage than when it's just running on battery! No issues before with the tail lights when they were non LED. Plus everything works fine on battery so I know the wiring works for the features to be activated.

 

[crash68]

People usually have this problem with the front lights, it probably caused by how the vehicle monitors the lights.
You can probably use AlfaOBD to reconfigure the vehicle lights or you can buy plug in LED load resistors to resolve the issue.

 

[htech402]

Thanks for the reply. I do have resistors that are on the lights. 50w 8 ohm.

 

[Atcer2018]

Thanks for the reply. I do have resistors that are on the lights. 50w 8 ohm.

Have you tried the new tail lights without the resistors? If the new lights are already internally wired for 12V (CANBUS ready) use you may have introduced too much line resistance with the external resistors.

 

[htech402]

Have you tried the new tail lights without the resistors? If the new lights are already internally wired for 12V (CANBUS ready) use you may have introduced too much line resistance with the external resistors.

I have not. They are attached to the taillight assembly that came pre installed on the part.

 

[Atcer2018]

I have not. They are attached to the taillight assembly that came pre installed on the part.

Well dang there goes my theory. Have you tried reinstalling the OEM tail lights and see if they work correctly? If the factory lights work as they should it kinda points to the new tail light assembly. Have you tried contacting the tail light manufacturer and asking if they have a solution?

 

[htech402]

Well dang there goes my theory. Have you tried reinstalling the OEM tail lights and see if they work correctly? If the factory lights work as they should it kinda points to the new tail light assembly. Have you tried contacting the tail light manufacturer and asking if they have a solution?

Thanks for the idea. I will check to make sure they did in fact work flawless before. Im sure they did but not 100%. These were from Amazon and instructions are limited.

 

[htech402]

I read on another forum that someone had some issues with an LED taillight kit. The replaced the flasher relay with a 552 relay. I assume since when the engine is off and everything works fine it wouldn't be the flasher relay? Or does it act differently when the vehicle is on.

 

[crash68]

@htech402 these trucks don't use a flasher relay, the lights are driven via PWM from the BCM. It's because of how the truck detects if a bulb is out that causes some LED bulbs to not work correctly, if the system detects too much or not enough current going through the lights in the truck the BCM will turn them off. I found this out back when I installed LED bulbs in my fog lights without the error canceler installed (they came with the LEDs).
I'm surprised your having problems with the taillights if they have resistors built into them. You might want to look into buying AlfaOBD to be able to configure your lights as LED(its a very useful app that does a lot more than vehicle configuration changes).
The other possiblity is there's something wrong with those LED taillights.

 

[DeputyChef22]

Lasfit has been an extremely reliable brand for me and they make resistors for tail lights. Best bet is to look on eBay.

 

[RamDiver]

I agree with Atcer2018, my first inclination would be to remove the resistor but, if that process is too difficult then contacting the manufacturer or distributor would be the next best action.

You might be surprised at how responsive some of the suppliers can be on Amazon, it might be worth the effort.

Also, could you post the Amazon link so we have more precise info on the product?


In summary, these 3 recommendations are your best bet, AFAIC.

Remove or disconnect a resistor as a test.
Contact the supplier.
Or find someone nearby with AlfaOBD/buy your own and set the LED Tail lamps as 'Present'.




.

 

[htech402]

I agree with Atcer2018, my first inclination would be to remove the resistor but, if that process is too difficult then contacting the manufacturer or distributor would be the next best action.

You might be surprised at how responsive some of the suppliers can be on Amazon, it might be worth the effort.

Also, could you post the Amazon link so we have more precise info on the product?


In summary, these 3 recommendations are your best bet, AFAIC.

Remove or disconnect a resistor as a test.
Contact the supplier.
Or find someone nearby with AlfaOBD/buy your own and set the LED Tail lamps as 'Present'.


View attachment 556097

.

 

[Atcer2018]

I read on another forum that someone had some issues with an LED taillight kit. The replaced the flasher relay with a 552 relay. I assume since when the engine is off and everything works fine it wouldn't be the flasher relay? Or does it act differently when the vehicle is on.

Like Crash stated our “newer” trucks don’t have flasher relays. Here is a shot in the dark…. Have you owned the truck since new? The reason I ask is because if someone owned the truck before you they may have used something like AlfaOBD to change the lighting to LED while they owned it and now you are using new lights with resistors attached. Any chance you physically looked at just the bulb on the old lights? Could those old light bulbs be LED from a previous owner? Many of us don’t replace the whole light assembly we just use LED bulbs in the OEM housing. It’s a long shot but worth a look.

 

[htech402]

I really appreciate the help everyone! So I put the factory bulbs back on and everything works as expected. All the features work when LED is hooked up. When running the vehicle turn and brake do not fully illuminate like they do when vehicle is off. I have switched the connectors in the bulb connectors and the same happens. I unplugged the battery to reset things to see if that will work and did not.

I changed all the lights to new bulbs and put the old cover back on so I can drive it again.

This is the tail light I have been fighting with: https://www.amazon.com/SINYATO-INDU...ights&qid=1733680708&sprefix=,aps,145&sr=8-24

I am original owner and have not added any after market electrical before this. I will take some time and do some research and see what I can find electrical wise. Try to call China and see if I can get answers from the vendor.

I think when its running on battery before truck turns on it must some how apply electrical dc currents differently than when running. I’m in IT but vehicles are a little foreign to me.

 

[crash68]

This is the tail light I have been fighting with

It's a bit ominous buying something with so few reviews, good bad or indifferent.
I'd be thinking of returning them if that window hasn't closed yet and go with a product that's known a little more.

 

[RamDiver]

Try to call China and see if I can get answers from the vendor.

Rather than challenge yourself by calling China, you can let Amazon assist you.

Click on Returns & Orders in the upper-right corner, your recent orders should be displayed.




Click on 'Leave seller feedback', if there are multiple items, scroll down to the item in question. In the comments box, describe the problem and ask what they recommend trying to resolve the fault.

If it were me, I wouldn't add a rating yet, nor respond to the 'Item as described by the vendor' question. Save both of those for later, if the vendor requires more incentive to respond positively and in a helpful manner.




Many of the Amazon vendors are very sensitive and quick to respond to buyer feedback.
This specific vendor has likely spent a boatload of $ on their vendor page and everything I read was in proper English, unlike most foreign vendors.

My guess is they will be very helpful if you treat them respectfully. Please keep us posted on your progress.

.

 

[Jebb]

Thanks for the reply. I do have resistors that are on the lights. 50w 8 ohm.

That is possibly the problem right there. 8 ohms is commonly used to compensate LED headlights but taillights are much lower current. I suspect that when the engine is running the PCM is detecting too much load on those taillights (as if there is a short) causing it to shut them off. Then on the next cycle it turns them back on - detects a "short" - and turns them back off, etc., etc. If you put a scope or AC meter across that taillight connector when the engine is running you will likely see pulsating voltage which is what's causing the dim bulb.

In other words, that 8 ohm resistor may be too much load. You need enough load there to emulate the stock bulb but not so much that the PCM thinks it's a short. You say the resistor is built in but, if you can, try changing it to a higher resistance value like 16 ohm, etc.

 

[htech402]

That is possibly the problem right there. 8 ohms is commonly used to compensate LED headlights but taillights are much lower current. I suspect that when the engine is running the PCM is detecting too much load on those taillights (as if there is a short) causing it to shut them off. Then on the next cycle it turns them back on - detects a "short" - and turns them back off, etc., etc. If you put a scope or AC meter across that taillight connector when the engine is running you will likely see pulsating voltage which is what's causing the dim bulb.

In other words, that 8 ohm resistor may be too much load. You need enough load there to emulate the stock bulb but not so much that the PCM thinks it's a short. You say the resistor is built in but, if you can, try changing it to a higher resistance value like 16 ohm, etc.

That's how it acts exactly. I assumed since it was paired with a 50W 8ohm that would be correct but maybe it's not so universal to RAM models. It actually sits outside the assembly on the back so I can snip the wires and add them to a different resister really easy. I would want to try 16 ohms next? Keep the 50w? It's labeled as a 50W 8O ohm and there is a letter J. Does J mean anything?

 

[Jebb]

That's how it acts exactly. I assumed since it was paired with a 50W 8ohm that would be correct but maybe it's not so universal to RAM models. It actually sits outside the assembly on the back so I can snip the wires and add them to a different resister really easy. I would want to try 16 ohms next? Keep the 50w? It's labeled as a 50W 8O ohm and there is a letter J. Does J mean anything?

Is it labeled "50W 8 ohm" or "50W 80 ohm"? If it's 80 ohms then it's probably too much resistance. Don't know about the "J" suffix but at 8 ohms it needs to be at least 25W, so stick with a 50W rating.

The PCM is likely set up to detect a certain current range so you have to find out what that range is for it to work right. Headlights and taillights will likely be different ranges. A resistor that works for headlights may not be the right value for taillights. Could be the manufacturer of your taillight is using the same resistor for everything and therefore doesn't work right, IDK.

 

[htech402]

It is labeled 50@w 8 ohm. I have ordered a pair of 10 and 16 to see if that will work! Really appreciate your help and its giving me a place to start and check resistance.