Tail Light Flicker - PWM frequency adjustment

[PetePerkins]

I also posted this in the Forscan forum.

I've searched but I have not found any topic in regards to PWM frequency adjustment. Long story short for a familiar problem, but I'm going at it from a new perspective...I think

I have a 2024 Bronco that I swapped out the rear halogens for OEM LEDs. All works fine with the exception of PWM flicker coming from the parking lights only. When looking at the attached wiring diagram coming from the BCM for both LED and Halogen equipped trucks, they both use the same Blue-Gray wire from the RP2 Bus. This tells me that there must be an asbuilt PWM adjustment where the pwm rate can be updated for Halogen or LED equipped trucks.

Any help or ideas with this would be greatly appreciated

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[Umichigan1]

I also posted this in the Forscan forum.

I've searched but I have not found any topic in regards to PWM frequency adjustment. Long story short for a familiar problem, but I'm going at it from a new perspective...I think

I have a 2024 Bronco that I swapped out the rear halogens for OEM LEDs. All works fine with the exception of PWM flicker coming from the parking lights only. When looking at the attached wiring diagram coming from the BCM for both LED and Halogen equipped trucks, they both use the same Blue-Gray wire from the RP2 Bus. This tells me that there must be an asbuilt PWM adjustment where the pwm rate can be updated for Halogen or LED equipped trucks.

Any help or ideas with this would be greatly appreciated

I am about to swap my OEM halogens for OEM LED. Can you offer any advice?

 

[Bron.co6g.Jim]

I truly think the Bronco community could benefit from finding which Forscan parameter changes the PWM frequency.... I have now spent days testing taillights from all different manufacturers (including OEM) to finally put to rest how to convert your Halogen equipped Bronco to a functioning LED vehicle. I believe my final hurdle is to let the vehicle know that the rear DRL and Brake function are now LED. This (I believe) will eliminate inconsistency's such as tail light "flicker" or the running lights turning OFF when fast pumping the brake pedal.

 

[PetePerkins]

I truly think the Bronco community could benefit from finding which Forscan parameter changes the PWM frequency.... I have now spent days testing taillights from all different manufacturers (including OEM) to finally put to rest how to convert your Halogen equipped Bronco to a functioning LED vehicle. I believe my final hurdle is to let the vehicle know that the rear DRL and Brake function are now LED. This (I believe) will eliminate inconsistency's such as tail light "flicker" or the running lights turning OFF when fast pumping the brake pedal.

Tell me about it! There must be a way to tell the Bronco that the tails are no longer Halogen but LED. Just yesterday I contacted a tech at the dealer and bribed him with $50 if he could figure it out using IDS or FDRS...waiting to hear back.

I don't think I've encountered the fast pumping brake pedal/running light outage. I'll need to test that. Does that happen with aftermarket lights or OEM or both? Does it happen with both tail and headlights?

 

[flip]

 

[Bron.co6g.Jim]

The "quick pump" light outage issue Im seeing is mostly (if not solely) from aftermarket taillight options when combined with a Halogen based vehicle (even after Forscaning). Removing that same exact aftermarket light and installing it to a LED equipped vehicle..... NO PROBLEM! Going down yet another rabbit hole..... The Black Diamond vehicle im working on with Halogen lighting has a traditional Vacuum brake booster w/ master cylinder. Underneath the dash you'll find a brake light switch. The Badlands vehicle I have with LED's has a full electronic and hydraulic master cylinder with NO vacuum assist. Underneath the dash it uses a completely different brake pedal assembly with NO brake light switch. This tells me that Brake activation between the two vehicles is completely different!

 

[Umichigan1]

I'm sure this is helpful in some way but I personally haven't the foggiest idea what to do with it.

 

[flip]

I'm sure this is helpful in some way but I personally haven't the foggiest idea what to do with it.

The problem is more than likely the new lamp circuitry if I had to guess. According to the parts catalogue there are only two BCM options which is just build date breaks and not sorted by options. This means it's all in the VIN specific software.

To include or exclude the vehicle as the concern someone is going to need to get an oscilloscope out and check both a LED and non-led park light circuits to see if there's any difference. If there is, it means either changing the programming with Forscan or putting some kind of module in line to fix the signal. I looked at the module options in the WSM and it doesn't look like FDRS allows modification of the park light function. It's either stock PMI or aftermarket like Forscan.

@Ducati1098 may have something to add that I may have misstated or missed.

 

[Bron.co6g.Jim]

Let's leave aftermarket lighting options out of this for the moment. In my case (and many others) only the OEM Signature Tail Lights suffer from the "flickering" running light issue. When I swap the same OEM LED light to a LED equipped vehicle, it doesn't do it.

 

[Ducati1098]

The problem is more than likely the new lamp circuitry if I had to guess. According to the parts catalogue there are only two BCM options which is just build date breaks and not sorted by options. This means it's all in the VIN specific software.

To include or exclude the vehicle as the concern someone is going to need to get an oscilloscope out and check both a LED and non-led park light circuits to see if there's any difference. If there is, it means either changing the programming with Forscan or putting some kind of module in line to fix the signal. I looked at the module options in the WSM and it doesn't look like FDRS allows modification of the park light function. It's either stock PMI or aftermarket like Forscan.

@Ducati1098 may have something to add that I may have misstated or missed.

I would agree this is most likely a programming related issue. Very unlikely anything FDRS will be able to change/fix. Forscan should be able to, but without having a non-led vehicle to test/play with I won’t be much help determining what programming needs to be changed in forscan.

The "quick pump" light outage issue Im seeing is mostly (if not solely) from aftermarket taillight options when combined with a Halogen based vehicle (even after Forscaning). Removing that same exact aftermarket light and installing it to a LED equipped vehicle..... NO PROBLEM! Going down yet another rabbit hole..... The Black Diamond vehicle im working on with Halogen lighting has a traditional Vacuum brake booster w/ master cylinder. Underneath the dash you'll find a brake light switch. The Badlands vehicle I have with LED's has a full electronic and hydraulic master cylinder with NO vacuum assist. Underneath the dash it uses a completely different brake pedal assembly with NO brake light switch. This tells me that Brake activation between the two vehicles is completely different!

The brake system changes depending on the engine equipped. The 2.7 gets the EBB system while the 2.3 has a conventional system.

 

[PetePerkins]

Let's leave aftermarket lighting options out of this for the moment. In my case (and many others) only the OEM Signature Tail Lights suffer from the "flickering" running light issue. When I swap the same OEM LED light to a LED equipped vehicle, it doesn't do it.

To add to this, my 24 Black Diamond OEM swapped LED tails only flicker/pulsate when the engine is running. When the engine is off the tails do not flicker.

 

[PetePerkins]

I found this FORScan spreadsheet for 2015-2020 F150s...

In the BCM (JUST) tab there is a section marked Duty_VRMS as well as RMS.

There is also a "Frequency Select Cfg section with options for LED or Halogen

	726-26-01	xxxx	xxx*	xxxx	Ctrl Stop Position Cfg	0=Duty_Duty, 1=Duty_VRMS, 2=VRMS_Duty, 3=VRMS_VRMS

726-26-02

xxxx

xxx*

xxxx

Frequency Select Cfg

0=Type 0 (LED), 1=Type 1 (Halogen), 2=Type 2, 3=Type 3

It was mentioned in the Forscan forum that I should be looking to modify RMS for flicker.

Tomorrow I will look at my BCM configs in Forscan to see if any of those asbuilt addresses are available in my Black Diamond.

It seems the 726 address deals with all lighting

 

[Bron.co6g.Jim]

To add to this, my 24 Black Diamond OEM swapped LED tails only flicker/pulsate when the engine is running. When the engine is off the tails do not flicker.

Same findings here too!

 

[Bron.co6g.Jim]

I would agree this is most likely a programming related issue. Very unlikely anything FDRS will be able to change/fix. Forscan should be able to, but without having a non-led vehicle to test/play with I won’t be much help determining what programming needs to be changed in forscan.



The brake system changes depending on the engine equipped. The 2.7 gets the EBB system while the 2.3 has a conventional system.

This is good news for me! If I head over to Ford's website and "build" a vehicle. I have the option (on some trim levels) to order a 2.3l w/ Signature Lighting Package. Which tells me the conventional vacuum braking system is compatible with a OEM LED taillight upgrade. Furthermore not REQUIRING the EBB system to trigger the BCM.

 

[Bron.co6g.Jim]

Since we're on to something here.... I have a bit more information from observing the two vehicles side by side (Halogen vs. LED).

The OEM LED equipped vehicle has a "sustain" to the brake light when first activated.... Meaning the brake light stays on for approximately 1-1.5 seconds AFTER depressing the brake pedal, even if you instantly remove your foot from the brake.

While the Halogen equipped vehicle brake light activation is instantaneous ON & OFF...

I wonder if there is a brake light activation sustain parameter as well?.... The lighting characteristic appears to follow which ever chassis the OEM light is installed in. So it must be signal activated.

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