What's new
By:
5thGenRams Forums

Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

Key Fobs and LED interference

I put in the Lasfits in the cargo lights and 3rd brake light and am having "Key Fob Not Found" issues. If I get in after the truck sitting for a while I get the error. If it's been running a while I can kill the truck and restart with no problem. Has anyone else had any issues with the Lasfits?
 
Jayturk said:
I have those and I am having intermittent issues.
Click to expand...
I replaced my LED's with the stock bulbs and no issues whatsoever. I had to take my truck in for the dreaded sliding rear window and had them check out the "Key fob has left the vehicle" and "Key Fob not detected." Of course they were not able to reproduce the warnings but left the attached in the vehicle.
 

Attachments

  • 156A9FDF-5FF4-43E5-A376-8E46CFE6A533.jpeg
    156A9FDF-5FF4-43E5-A376-8E46CFE6A533.jpeg
    81.5 KB · Views: 153
That’s why you pay the extra and get Diode Dynamics, zero issues since installed.
 
gHiDoRa said:
Anybody using 3rd brake LED from Lasfit? Does it interference with our FOB?
Click to expand...
I did and have a return
gHiDoRa said:
Anybody using 3rd brake LED from Lasfit? Does it interference with our FOB?
Click to expand...
Yes they interfere will be pulling out this afternoon. Returning as they said they could not fix this. They paid postage also and crediting my card.
 
Ok guys your all missing a huge step.
First our trucks can come with LED lights. Their is programming that MUST BE ENABLED for things to not get stupid. Regular lights have voltage differences and LED forward voltage difference when not seen the BCM will go nuts. Get Alfa OBD and go to BCM go to the LED light section and enable CHMSL led present yes. Rather NO.
Your welcome.
If your in western mass, happy to help seeing I have the hardware
 
dschweers said:
I did and have a return

Yes they interfere will be pulling out this afternoon. Returning as they said they could not fix this. They paid postage also and crediting my card.
Click to expand...
LasFit 3rd brake light and cargo lights for a month, no issues with my Ram.
 
Has anyone noticed that there key fob is less responsive after changing the interior lights out for LED, i used Lastfit LED and noticed now if i try to hit unlock or lock multiple times after the first time it doesn’t respond. Once the interior lights turn on from first push of the button the fob doesn’t respond till i am really close to vehicle. I turned the interior lights off and it works fine.
 
I recently installed Lasfits in my CHMSL as well as replaced all my interior bulbs and am running into the occasional key fob issue. Most of the time there is no problem, but every once and a while it will not register the lock/unlock or will say the fob is not in the vehicle and won't start. Given it is not frequent, I'll give it a go for a while and if it continues I may swap the CHMSL bulbs to a different brand. Been playing around with it and I am finding a few situations where the fob is more likely to throw an error:
  • Starting the truck with a door open (causes all three CHMSL bulbs to be on at the same time while trying to start the truck)
  • Keeping foot on brake for some time before pressing the ignition button
  • Pressing the fob too many times while the lights are on
  • If there's an area where the connectivity is generally poor (eg. in my parking garage which has a steel roof and concrete walls)
90% of the time there are no issues, but I'm trying to reduce some of these situations and see if it makes a difference.
 
I figured out little bit of a trick. If you are about to start the car dont press the break push start first which will turn the accessory mode or whatever is called and than step on the break and push start again you will be able to turn the car without taking your key out of your pocket.
 
I figured out a trick too! Program your truck to accept the correct bulb, and have ZERO issues.
Ask me how I know. Lol

Again, if you don’t have AlfaOBD then get it, or find someone who does! Enable each light for LED that you’ve replaced. Trust me, each light has a location and option for LED!!! Even the plate lights!
So, program your truck and finish the mod properly! I can’t tell you how the other trucks are not having issues, I can only tell you how to fix it and where.
 
Bruins5515 said:
Has anyone noticed that there key fob is less responsive after changing the interior lights out for LED, i used Lastfit LED and noticed now if i try to hit unlock or lock multiple times after the first time it doesn’t respond. Once the interior lights turn on from first push of the button the fob doesn’t respond till i am really close to vehicle. I turned the interior lights off and it works fine.
Click to expand...
LASFIT in CHSML and all interior lights with no issues.
 
Shives said:
I figured out a trick too! Program your truck to accept the correct bulb, and have ZERO issues.
Ask me how I know. Lol

Again, if you don’t have AlfaOBD then get it, or find someone who does! Enable each light for LED that you’ve replaced. Trust me, each light has a location and option for LED!!! Even the plate lights!
So, program your truck and finish the mod properly! I can’t tell you how the other trucks are not having issues, I can only tell you how to fix it and where.
Click to expand...
Do you have a guide or steps to do this? I have AlfaOBD and lasfits and started running into this keyfob interference issue.
 
Started having issues here as well with LASFIT. Put in Diode Dynamics, and they aren't quite as bright because they don't have any LEDs pointing straight out, they rely on the reflectors. However, no more interference issues.

If it truly is interference, I do not see how telling the computer that there are LEDs will help. If the computer was triggering a bulb out warning or something, it would help with that, but interference is not caused because the computer doesn't know its LEDs, interference is caused by cheap or low-grade LEDs.

If anyone had the issue, and setting the computer to LED 3rd brake lights resolves it, I'm all ears; would be happy to be proven wrong.
 
UnloosedChewtoy said:
Started having issues here as well with LASFIT. Put in Diode Dynamics, and they aren't quite as bright because they don't have any LEDs pointing straight out, they rely on the reflectors. However, no more interference issues.

If it truly is interference, I do not see how telling the computer that there are LEDs will help. If the computer was triggering a bulb out warning or something, it would help with that, but interference is not caused because the computer doesn't know its LEDs, interference is caused by cheap or low-grade LEDs.

If anyone had the issue, and setting the computer to LED 3rd brake lights resolves it, I'm all ears; would be happy to be proven wrong.
Click to expand...
Let’s start with the actual reason why LEDs cause the key fob to not be detected. Every LED (the actual light emitting diode chip) needs some kind of driver to operate, and the drivers naturally emit high frequency, which in turn generates electromagnetic interference. Manufacturers correct this by adding some sort of filtering, usually in the form of a “canbus error canceller” or “anti flicker” device, but in replacement bulbs of this size, they build the filter right onto the bulb board. The RF Hub on Ram trucks (the receiver for the fobs and TPMS system) is located on the back wall pretty much directly below the CHMSL. Since the brake pedal needs to be pressed to start the truck....well, we all know the rest. The BCM on our trucks uses PWM (pulse width modulation) on all exterior light circuits that use halogen bulbs. This PWM rapidly turns the circuit on and off in different duty cycles to extend bulb life and prevent dimming when the alternator is under heavy load. When a truck is optioned with LEDs in particular locations, the BCM is configured to not use PWM on those circuits. That is what AlfaOBD is doing when you enable or disable the LED locations in the CBC Features list. If an LED manufacturer implements crude or poor filtering circuits, the PWM can disrupt the filter’s ability to start doing it’s job, and allow EMI to be generated. Since most LEDs are manufactured in uncontrolled environments, any LED is capable of doing this. That’s why some will say “this bulb worked for me”, but the same one doesn’t for others, no matter who the manufacturer is. Using AlfaOBD to disable the PWM on the CHMSL is not guaranteed to stop this interference all together, but greatly reduces the chances of it happening. Obviously, if somebody finds a bulb that works for them, then there’s no reason to buy AlfaOBD just for that, but if you already have AlfaOBD, it will give you more leeway on bulb selection.
 
Last edited:
I replaced the two white cargo light bulbs right after I got the truck. Then later I replaced the third break light. I started getting the "keyfob not detected" error, but I had no idea why. I'm glad I came across this thread. I replaced the third break light with the factory bulb and I have not had that issue again. Its been a couple weeks now so I'm happy. I might try another red LED, but I might just leave it alone.
 
You must log in or register to reply here.

Users who are viewing this thread

Total: 1 (members: 0, guests: 1)

Site Vendors

https://www.jasonlewisautomotive.com/

Members online

Total: 394 (members: 31, guests: 363)
Back
Top