How to convert from factory LED taillights to incandescents, AlfaOBD help

[ksdoit]

I want to eliminate the crappy aftermarket LED taillights that “fast dash blink” because computer thinks they aren’t working.

And while it’s a great business model to build insanely complex electronics to ensure compliance towards dealer only services and multiple hundred dollars parts, my principles cause me to want that old $5 incandescent bulb do-it-yourself sanity of yesteryear.

So, After modifying harness the LED harness for a standard two bulb non-LED taillight, and despite trying numerous AlfaOBD settings that ought to disable its DTC monitor, turn off LED, etc, I still have “fast dash blink” after clearing codes. My new non-LED harness mod and taillights work correctly from the outside cab perspective.

What am I missing? Do I need to do something with the unused red LED wire from LED harness, or some other AlfaOBD settings that is non obvious?

Help…

P.S. I traded in my damn Silverado for a RAM because it’s built in trailer brake controller dinged me to death driving down the highway, usually telling me I had trailer issues when no trailer was connected. After several thousand dollars, multiple dealer visits, I gave up. Don’t make me cave to Toyota to get better electronics! Please help.

 

[SitKneelBend]

I want to eliminate the crappy aftermarket LED taillights that “fast dash blink” because computer thinks they aren’t working.

And while it’s a great business model to build insanely complex electronics to ensure compliance towards dealer only services and multiple hundred dollars parts, my principles cause me to want that old $5 incandescent bulb do-it-yourself sanity of yesteryear.

So, After modifying harness the LED harness for a standard two bulb non-LED taillight, and despite trying numerous AlfaOBD settings that ought to disable its DTC monitor, turn off LED, etc, I still have “fast dash blink” after clearing codes. My new non-LED harness mod and taillights work correctly from the outside cab perspective.

What am I missing? Do I need to do something with the unused red LED wire from LED harness, or some other AlfaOBD settings that is non obvious?

Help…

P.S. I traded in my damn Silverado for a RAM because it’s built in trailer brake controller dinged me to death driving down the highway, usually telling me I had trailer issues when no trailer was connected. After several thousand dollars, multiple dealer visits, I gave up. Don’t make me cave to Toyota to get better electronics! Please help.

Do you have a link for the lights you purchased?

 

[ksdoit]

Do you have a link for the lights you purchased?

Yes, see below.

These are the bulbs I am using within a standard (non-LED) housing for RAM 4th gen. My truck is a 2016 Ram 1500 Laramie, which came with the factory LED harness and an LED for its park, brake, and turn functions, and an incandescent bulb for its reverse.

To reiterate, I want to decommission an LED taillight and replace it with a non-LED (incandescent) taillight, and I am using the following bulbs:


Bulb #1:

https://shop.advanceautoparts.com/p...andard-performance-2-pack-3157llbp2/5081912-P

This bulb is for running, brake, & blink/turn.


Bulb #2:

https://shop.advanceautoparts.com/p...tandard-performance-2-pack-194llbp2/5081874-P


This bulb is for reverse backup.

 

[SitKneelBend]

Yes, see below.

These are the bulbs I am using within a standard (non-LED) housing for RAM 4th gen. My truck is a 2016 Ram 1500 Laramie, which came with the factory LED harness and an LED for its park, brake, and turn functions, and an incandescent bulb for its reverse.

To reiterate, I want to decommission an LED taillight and replace it with a non-LED (incandescent) taillight, and I am using the following bulbs:


Bulb #1:

https://shop.advanceautoparts.com/p...andard-performance-2-pack-3157llbp2/5081912-P

This bulb is for running, brake, & blink/turn.


Bulb #2:

https://shop.advanceautoparts.com/p...tandard-performance-2-pack-194llbp2/5081874-P


This bulb is for reverse backup.

So your truck came with factory LED tails right? Do you have AlfaOBD?

 

[ksdoit]

So your truck came with factory LED tails right? Do you have AlfaOBD?

Yes, my truck came with factory LED taillights.

Yes, I have AlfaOBD. I have read everything on this forum related to this "LED taillight issue" and tried numerous settings that ought to work, but they DO NOT WORK. Please keep in mind, however, I am going in the opposite direction of what is commonly discussed. I do not want to add LED tailights. I bought this Ram 1500 Laramie used. It had crappy after-market LED taillights installed, obviously to replace the factory ones that had already failed. Do you think that if I walk into the dealer with original or aftermarket LEDs that don't work, they are going to offer anything other than a $ 1,000 solution of factory LEDs to "fix it"? Again, I want to have simple $5 bulbs. I am hoping that someone here on the forum, has a solution for this.

My assumption is that I need another AlfaOBD setting or combination of settings and/or I need to address the unused red wire from the LED harness.

These are the settings I have changed via AlfaOBD:

Rear Lighting DTC Disabled (set to yes)
(By its name, this one along, OUGHT to fix this, but it does not, the computer via its DTC is still analyzing the line and deeming a problem even though the lights work. It throws codes B1642 B1646)
LED Reverse Lamps Present (set to no)
LED Stop Lamps Present (set to no)
LED Rear Turn Lamps Present (set to no)
LED Tail Lamps Present (set to no)

Reverse Lamps Open Circuit DTC Enabled (tried both yes and no)
Stop Lamps Open Circuit DTC Enabled (tried both yes and no)
CHMSL Lamp Open Circuit DTC Enabled (tried both yes and no)
Rear Park Lamps Open Circuit DTC Enabled (tried both yes and no)

Left Rear Corner Voltage (experimented with this, but nothing helps)
Right Rear Corner Voltage (experimented with this, but nothing helps)

Extern.Light Calibr.-Left Rear Corner Voltage (experimented with this, but nothing helps)
Extern.Light Calibr.-Right Rear Corner Voltage (experimented with this, but nothing helps)

I have also checked the ground continuity from the bulb to the battery negative and it is good (under 1 Ohm).

And to repeat again. My non-LED taillights work perfectly from the outside. They blink at the normal rate. They shine at the normal brightness. I am trying to resolve and fix the internal false codes and hyper-fast blinking from within the cab. The single setting "Rear Lighting DTC Disabled" should stop the computer from doing this bad analysis but it is not. So either there is another setting I am needing to also set, or something else unknown. Please anyone who can help?

 

[ksdoit]

Also, in the factory LED taillight harness (six pins, but only five wires), the red line that I have NOT currently hooked to (as there is nothing to attach it to in an incandescent setup like I am attempting) is probably what might be called the "turn lamp false sense" wire. This is the wire that I have been hinting about, but no one has responded to that yet.

But I have just discovered a new document. From this document:

https://www.ramtrucks.com/assets/bbg/pdf/2016/docs/ram/ramelm.pdf

I am concluding that the "red" wire is the "turn lamp false sense" wire. Can anyone confirm this? And if so, is this PDF's solution (which is really for the 2500 or higher models) what I need to do for my 1500?. I again would think that the AlfaOBD "Rear Lighting DTC Disabled" ought to fix it programmatically, but it has not worked for me.

In any event, the PDF lists one of several solutions for "circuit L950 is a blunt cut LG/WT wire that can be grounded to disable rear bulb out detection."

Has anyone dealt with this issue on a 4th-gen RAM 1500?

 

[04fxdwgi]

If this would help, I have OEM LED's in my truck, a '16 Sport. I can post my BCM print out and you can compare it to yours and possibly get the LED's working. That would be a good place to start to see what is possibly going on.

Perhaps someone could post their printout, too, if they have the Non-LED configuration in their truck and compare the LED to Non-LED

 

[PolarisCobra]

Just throwing it out there, in case you missed something simple - Are you sure that there are no issues with a failed light in the front? This would also cause the fast blinking if there was a light out. Just want to make sure you aren't looking at the wrong end of the truck.

 

[ksdoit]

Just throwing it out there, in case you missed something simple - Are you sure that there are no issues with a failed light in the front? This would also cause the fast blinking if there was a light out. Just want to make sure you aren't looking at the wrong end of the truck.

Yes, I am sure there are no failed lights anywhere on the truck (including the fronts).

I think at this point, I am down to 3 options:

1. Discover an AlfaOBD setting or a combination of them that somehow disables the CBC from throwing false information (my CBC throws codes, hyper flashes in the cab, when ALL lights are working perfectly). This first option seems increasingly unlikely, but hopefully, there is still someone out there with new information.

2. Dealing with that unused (now that I am not using LED taillights) "red wire," which is the "turn lamp false sense" wire, perhaps by trying to find it in the engine bay and grounding it per "Method B" in this document: https://www.ramtrucks.com/assets/bbg/pdf/2016/docs/ram/ramelm.pdf. It is not clear, however, whether this is even an option on a 1500 truck, as the document is inconsistent regarding its use cases.

3. Asking my RAM dealer service center if they will do the "Method A" as outlined in this same document: https://www.ramtrucks.com/assets/bbg/pdf/2016/docs/ram/ramelm.pdf. But I expect they will say they cannot do so because it is not a heavy-duty truck (for legal regulatory reasons).

 

[ksdoit]

If this would help, I have OEM LED's in my truck, a '16 Sport. I can post my BCM print out and you can compare it to yours and possibly get the LED's working. That would be a good place to start to see what is possibly going on.

Perhaps someone could post their printout, too, if they have the Non-LED configuration in their truck and compare the LED to Non-LED

Thank you for sending your BCM printout.

I programatically diffed our two trucks' BCM settings and did not find anything new to try.

As expected, in your factory-LED taillight truck, regarding the supposedly applicable settings, your settings were:

Rear Lighting DTC Disabled: No
LED Stop Lamps Present: Yes
LED Rear Turn Lamps Present: Yes
LED Tail Lamps Present: Yes

And in my attempt to decommission LED taillights, I have mine the opposite of:

Rear Lighting DTC Disabled: Yes
LED Stop Lamps Present: No
LED Rear Turn Lamps Present: No
LED Tail Lamps Present: No

Yet the CBC computer is still giving me the hyper-flash in the cab and throwing the codes.

If anyone out there has a 2016 RAM 1500 Big Horn (or any trim below a Laramie) and would be willing to share their configuration, that would be most welcome.

 

[SitKneelBend]

Also, in the factory LED taillight harness (six pins, but only five wires), the red line that I have NOT currently hooked to (as there is nothing to attach it to in an incandescent setup like I am attempting) is probably what might be called the "turn lamp false sense" wire. This is the wire that I have been hinting about, but no one has responded to that yet.

But I have just discovered a new document. From this document:

https://www.ramtrucks.com/assets/bbg/pdf/2016/docs/ram/ramelm.pdf

I am concluding that the "red" wire is the "turn lamp false sense" wire. Can anyone confirm this? And if so, is this PDF's solution (which is really for the 2500 or higher models) what I need to do for my 1500?. I again would think that the AlfaOBD "Rear Lighting DTC Disabled" ought to fix it programmatically, but it has not worked for me.

In any event, the PDF lists one of several solutions for "circuit L950 is a blunt cut LG/WT wire that can be grounded to disable rear bulb out detection."

Has anyone dealt with this issue on a 4th-gen RAM 1500?

I believe they issue you're having is related to using an incandescent housing on a wiring harness that differs for the LED housing.

What I would do is get a nice set of LED tails configured for OEM LED wiring. If not interested I can post some wiring info for you. Just let me know...

 

[White six four]

The turn signals in the mirrors are working if your truck has then?

Have you made the changes with alfaobd and left them for a few drive cycles? When I added fog lights to my truck it took a few drives before they actually started working. Sometimes changes in alfaobd don't take place instantly.

Just a random thought but would any changes as far as led changed to no need to be done? I understand that halogen bulbs draw more current then leds so when one swaps in an led bulb where a halogen was the computer thinks the bulb is out. But the other way around would the computer care if a supposed led bulb was drawing more power (example original led bulb swapped for a halogen)? If it doesn't then to me changes in alfaobd wouldn't mean anything in your circumstance.

 

[ksdoit]

I believe they issue you're having is related to using an incandescent housing on a wiring harness that differs for the LED housing.

What I would do is get a nice set of LED tails configured for OEM LED wiring. If not interested I can post some wiring info for you. Just let me know..MOPAR will not work on non-OEM LED tails, thus, I am not sure one can say there are any such "nice set of LED tails" other than the ones that cost over $800 a pair.

I believe they issue you're having is related to using an incandescent housing on a wiring harness that differs for the LED housing.

Yes, I am aware of that. It is the unused "sense wire" that I am having issues with. Do you have a solution to connect it to something to disable the computer so it stops throwing codes and stops the hyper-blink inside the cab?

What I would do is get a nice set of LED tails configured for OEM LED wiring. If not interested I can post some wiring info for you. Just let me know...

As MOPAR dealerships will only work on their OEM taillights (which cost over $800 for the pair), I am not sure there is any such "nice set of LED taillights". Sure, I can take my chances on third-party cheapos until the next time the computer deems the non-OEM taillight non-functional and sets error codes and hyper-blinks. The whole point of my exercise was to go back to something reliable, cheap, and easy to fix. I am concluding that I should have bought a lower-trim RAM (Big Horn or lower) or a different brand, since I am getting burned by electronics once again.

 

[ksdoit]

The turn signals in the mirrors are working if your truck has then?

Yes they work, however they appear to hyper-blink also. The fronts and rears all blink at the correct blink rate.

Have you made the changes with alfaobd and left them for a few drive cycles? When I added fog lights to my truck it took a few drives before they actually started working. Sometimes changes in alfaobd don't take place instantly.

Yes, I have. In this case I believe its probably a non configurable issue and a solution probably is 100% related to doing something with the “sense wire” as mentioned in the earlier mentioned PDF.

Just a random thought but would any changes as far as led changed to no need to be done? I understand that halogen bulbs draw more current then leds so when one swaps in an led bulb where a halogen was the computer thinks the bulb is out. But the other way around would the computer care if a supposed led bulb was drawing more power (example original led bulb swapped for a halogen)? If it doesn't then to me changes in alfaobd wouldn't mean anything in your circumstance.

I agree, but AlfaOBD settings (I’ve tried numerous scenarios including this one, haven’t worked. I don’t think it can be changed via AlfaOBD and dealer refuses to flash anything (as per the PDF)

 

[Ritchie_Rich]

Yes, my truck came with factory LED taillights.

Yes, I have AlfaOBD. I have read everything on this forum related to this "LED taillight issue" and tried numerous settings that ought to work, but they DO NOT WORK. Please keep in mind, however, I am going in the opposite direction of what is commonly discussed. I do not want to add LED tailights. I bought this Ram 1500 Laramie used. It had crappy after-market LED taillights installed, obviously to replace the factory ones that had already failed. Do you think that if I walk into the dealer with original or aftermarket LEDs that don't work, they are going to offer anything other than a $ 1,000 solution of factory LEDs to "fix it"? Again, I want to have simple $5 bulbs. I am hoping that someone here on the forum, has a solution for this.

My assumption is that I need another AlfaOBD setting or combination of settings and/or I need to address the unused red wire from the LED harness.

These are the settings I have changed via AlfaOBD:

Rear Lighting DTC Disabled (set to yes)
(By its name, this one along, OUGHT to fix this, but it does not, the computer via its DTC is still analyzing the line and deeming a problem even though the lights work. It throws codes B1642 B1646)
LED Reverse Lamps Present (set to no)
LED Stop Lamps Present (set to no)
LED Rear Turn Lamps Present (set to no)
LED Tail Lamps Present (set to no)

Reverse Lamps Open Circuit DTC Enabled (tried both yes and no)
Stop Lamps Open Circuit DTC Enabled (tried both yes and no)
CHMSL Lamp Open Circuit DTC Enabled (tried both yes and no)
Rear Park Lamps Open Circuit DTC Enabled (tried both yes and no)

Left Rear Corner Voltage (experimented with this, but nothing helps)
Right Rear Corner Voltage (experimented with this, but nothing helps)

Extern.Light Calibr.-Left Rear Corner Voltage (experimented with this, but nothing helps)
Extern.Light Calibr.-Right Rear Corner Voltage (experimented with this, but nothing helps)

I have also checked the ground continuity from the bulb to the battery negative and it is good (under 1 Ohm).

And to repeat again. My non-LED taillights work perfectly from the outside. They blink at the normal rate. They shine at the normal brightness. I am trying to resolve and fix the internal false codes and hyper-fast blinking from within the cab. The single setting "Rear Lighting DTC Disabled" should stop the computer from doing this bad analysis but it is not. So either there is another setting I am needing to also set, or something else unknown. Please anyone who can help?

It’s entirely possible that the previous owner just wanted “cool looking” LED taillights instead of the original ones. Not that the original ones were bad. JMO

 

[04fxdwgi]

The old method of faking out the quick flash problem was to install a 25 ohm / 25 watt resistor as a load resistor (fake load to simulate an incandescent bulb load)

 

[SitKneelBend]

Yes, I am sure there are no failed lights anywhere on the truck (including the fronts).

I think at this point, I am down to 3 options:

1. Discover an AlfaOBD setting or a combination of them that somehow disables the CBC from throwing false information (my CBC throws codes, hyper flashes in the cab, when ALL lights are working perfectly). This first option seems increasingly unlikely, but hopefully, there is still someone out there with new information.

2. Dealing with that unused (now that I am not using LED taillights) "red wire," which is the "turn lamp false sense" wire, perhaps by trying to find it in the engine bay and grounding it per "Method B" in this document: https://www.ramtrucks.com/assets/bbg/pdf/2016/docs/ram/ramelm.pdf. It is not clear, however, whether this is even an option on a 1500 truck, as the document is inconsistent regarding its use cases.

3. Asking my RAM dealer service center if they will do the "Method A" as outlined in this same document: https://www.ramtrucks.com/assets/bbg/pdf/2016/docs/ram/ramelm.pdf. But I expect they will say they cannot do so because it is not a heavy-duty truck (for legal regulatory reasons).

Having trouble accessing the site but go here to learn the harness difference for tail light options.

Mopar Connection Repair Kit

connectorrepairkit.mopar.com

 

[Mercruth]

Just spitballing outschool here as I do not have the "computer" issues the newer truck do. But the flashing before stop light is an add on module seperate from the trucks own turn signals. Some dealers add that annoying 3 flash before steady modules to vehicles as a "safety feature". Sure your not fighting an after market add on feature, rather than a selection that came with your truck? Just saying......good luck. I don't have obdm so I don't have any help for that.

 

[BowhuntingRam]

The old method of faking out the quick flash problem was to install a 25 ohm / 25 watt resistor as a load resistor (fake load to simulate an incandescent bulb load)

I believe you need to figure out what the load rating is for the monitoring circuit. Most likely you just need to simulate that load on the red wire you are mentioning and fake it out.

 

[BowhuntingRam]

Also, in the factory LED taillight harness (six pins, but only five wires), the red line that I have NOT currently hooked to (as there is nothing to attach it to in an incandescent setup like I am attempting) is probably what might be called the "turn lamp false sense" wire. This is the wire that I have been hinting about, but no one has responded to that yet.

But I have just discovered a new document. From this document:

https://www.ramtrucks.com/assets/bbg/pdf/2016/docs/ram/ramelm.pdf

I am concluding that the "red" wire is the "turn lamp false sense" wire. Can anyone confirm this? And if so, is this PDF's solution (which is really for the 2500 or higher models) what I need to do for my 1500?. I again would think that the AlfaOBD "Rear Lighting DTC Disabled" ought to fix it programmatically, but it has not worked for me.

In any event, the PDF lists one of several solutions for "circuit L950 is a blunt cut LG/WT wire that can be grounded to disable rear bulb out detection."

Has anyone dealt with this issue on a 4th-gen RAM 1500?

Disregard my last post. Page 5 and 6 of this document tell you exactly what you need to do. If you need to confirm what wire it is for the false turn circuit, refer to a wiring diagram for your truck. 1500, 2500, 3500 will all be the same except chassis cab. At least from my digging when trying to resolve a reverse light issue with my 2012.