Light problem

[Mark 666]

All I can tell you is that the lights work fine in the warm weather and the left one stops working when the temperature goes below freezing. The third replacement light works on the passenger side and they are still trying to get a good one for the drivers side. I am sure nothing else is wrong with the truck they are producing faulty lights. Ford has told the dealer to keep ordering them until they get one that works. By your name I guess you are a mechanic so am I for the last 35 years.

 

[TwizzleStix]

The driver’s side light still flashes half as fast as the passengers side when the outside temperature drops below freezing. The dealer put the newest light in the freezer overnight before testing it and it failed. The service manager also told me both Raptors on the lot do the same thing so any one in a cold climate with a 2019 Raptor might want to check the rear hazards in the cold.

Need to clarify, is the problem occurring with the left or right turn signal command, or only with the 4-way emergency flasher, or with any signal command? What about the brake lights, are they functioning correctly?

I'm sure you know that earlier vehicles used a simple load-driven flasher that reacted to the resistance in the bulb/wire loop. Our newer flasher function is fully controlled by the BCM, regardless of the load, so any flash-rate problem is exclusively within the BCM. You should be able to insert a sharp probe into the bulb plug and measure the voltage with a simple multimeter to determine if the light unit is receiving the correct voltage pulse.

It would be a great help if you would post a video of exactly what you're observing.

 

[Mark 666]

The problem is with either the turn signal or the hazard switch. The light has a large amber rectangular turn signal separate from the brake light. I have video on my phone but I don’t know how to post them.

 

[melvimbe]

Need to clarify, is the problem occurring with the left or right turn signal command, or only with the 4-way emergency flasher, or with any signal command? What about the brake lights, are they functioning correctly?

I'm sure you know that earlier vehicles used a simple load-driven flasher that reacted to the resistance in the bulb/wire loop. Our newer flasher function is fully controlled by the BCM, regardless of the load, so any flash-rate problem is exclusively within the BCM. You should be able to insert a sharp probe into the bulb plug and measure the voltage with a simple multimeter to determine if the light unit is receiving the correct voltage pulse.

It would be a great help if you would post a video of exactly what you're observing.

is it possible that the problem is in the wiring between BCM and the bulb? Could you measure the voltage leaving the BCM and entering the bulb?

Another test they could do is place one of the bad lights in a different vehicle at the dealership and see what happens.

 

[TwizzleStix]

As I think about this some more it occurs to me that led bulbs have a “driver” in them that regulates the voltage to the led itself. If Ford tried to cut costs by buying cheaper led components )from China?), it very well could be a “batch” of light assemblies are junk.

It is simple troubleshooting to verify voltage at the bulb/light is correct as expected.

 

[Mark 666]

The dealer has verified that they have two more truck with the same problem and another truck that has been purchased. I agree with the cheap Chinese parts theory.

 

[Mark 666]

I don’t know if these videos help.

 

[Mark 666]

The first video was inside at 60 degrees and the second one was the next morning below freezing.

 

[TwizzleStix]

Yes that explains it. When cold, the rear lights flash on every other front light flash. In this case I would suspect the single point fault source as the BCM itself. I think it is the driver in the BCM rather than the rear light assemblies. The only way to verify is to do actual troubleshooting with a multimeter, or stick with the usual dealer goon method of just throwing parts at it. That way the goon at least gets paid to replace parts.

 

[Mark 666]

The replacement light in the passenger side works fine now even in the cold the problem is in the light itself.