Does anyone understand how the BCM on a C6 changes the repetition rate of the directionals when it senses a "bulb out" condition? I would like to disable this function.

 

It measures resistance, so put a resistor in to replace the bulb.

 

I tried that and it did not work.

 

The flasher is an R/C timer circuit. It relies on functioning bulbs to set the decay rate on the capacitance. When a bulb is out, the timing changes. It's just discreet electronics, there's no intelligent device doing it. At least not as far as I'm aware.

 

I could be wrong, but on a C6 there is no flasher. The repetition rate (pulse rate) is taken care of by the BCM. When there is a bulb out, the pulse rate changes to a more rapid rate. It seems logical that the BCM is looking for a certain resistance range, but I have tried adding series resistors and there is no change.
I didn't want to get into this much detail, but my problem started after installing the Morimoto LED headlights. This rapid flashing only occurs when the headlights are OFF.

 

Maybe I'm still thinking of my C5, but it would do the same thing. Then I stand corrected.

Have you asked Morimoto what the solution is?

 

Usually with those type of LED lights you need to parallel a resistor with the light to get the flasher circuit to have enough current to operate correctly. I have no idea, but I would not be surprised if on the c6, every output for the lights were individual and if it sensed one bad bulb it would change the flash rate on all to clue the driver that a bulb was out.

 

All of the directional LED's have load resistors on them to emulate incandescent bulbs. The only ones that don't are the headlights. Maybe the BCM is also monitoring the current draw on the headlight circuit and this is causing the directionals to rapid flash. This seems to be the only logical explanation.

 

The BCM runs a diagnostic and it's measuring current consumption. If the current consumption is too low because you switched from incandescent to LED, the BCM things the bulb is burned out, and does the fast flashing. The only reasonable solution i could find is to use parallel resistors. If you added resistors and it still flashes too fast, it just means you used the wrong resistance. What ohmic value did you add in parallel. The right value is pretty low, I know 8 Ohms works, which is huge power consumption, i have 50W, 8Ohm power resistors, bolted to the frame for heat dissipation, and i know those work, 10Ohms may or may not work, not sure.

It sucks that you have to waste power through a parallel resistor when you install efficient LEDs but i could not find a better solution. Theoretically it would be possible to turn off the diagnostic in the BCM, but i was unable to find anyone capable of changing calibrations in the BCM. if you find someone that has the ability to change BCM calibrations and reflash, let me know.

Even longer more confusing story: The front corner lights use the same bulb filament for DRLs and turn signal (there is a second filament inside the same bulb, used as parking light i think, but that's irrelevant to this conversation). I thought i was clever and put together a timer circuit that only turns on the power resistors when using the turn signal, but turns off the power resistors when the DRLs are running, i thought i was being smart by running efficient LED's and not wasting power in the resistors during the DRLs but it didn't work. At night, when the DRLs are off, my idea works perfectly, when i use the turn signal, the timer circuit puts the resistor in line, and the BCM sees the correct current consumption, and blinks correctly. But during the day when the DRLs are on, and my resistors are off, the BCM sees the current is too low and when i use the turn signal it flashes too fast, "hyperflash". So in summary i spent a bunch of effort trying to solve the problem, and it didn't work.

 

I see a bunch of people are using those new Morimoto headlights, i'm hoping someone will post here if they solved this problem.

Please let us know what you learn, i'd like to figure out a way to solve my problem as well.

I'd be curious to know what you mean by "all directional LED's have load resistors" for the C6, for North American cars, the turn signal and the DRL are the exact same wire, the exact same filament inside the bulb. it almost sounds like the morimoto solution has the same problem as my little timer circuit? works right at night, flashes too fast when the DRL's are on?

 

It sure would be cool to see the BCM programming, if not for anything but to defeat most of what it does.

 

Okay here goes:
I have the first generation Morimoto LED Headlights which incorporate LED front directionals. For many years now I have had Eagle Eye rear LED's which incorporate load resistors. The rear ones never caused a problem with the rate of flashing. Once I installed the Morimoto LED Headlights, I have had nothing but problems. At first there was no additional harness needed, then there was a first generation harness, then a second generation harness (which I have now). Each of these had their own set of problems.
This current set-up almost works EXCEPT when the headlights are off, the first time you initiate the turn signal, it will "rapid flash." If you turn the turn signal off, then on again for the same side, the problem goes away until you select the other turn signal in the opposite directional (again only the first time). This does not occur when the headlights are on.
BTW It is true that in order to make the BCM think that there is still an incandescent bulb installed you have to add a resister in parallel to the LED bulb. Each of the resistors I used were 6 ohm / 50 watts.
When I said that all of the LED's have load resistors, I was referring to each of the front two and each of the rear ones. I have tried increasing the resistance, decreasing the resistance and removing the resistance and this problem that I am describing still remains.
It could be that the BCM is also monitoring the current draw of the headlights. But if this is true the only time that would happen is when they are turned on, not when they are turned off.
If I could disable the sensing feature of the BCM somehow, I think this would solve my problem.

 

It gets better with these headlights. If you swap out the incandescent amber marker bulbs located on the front fenders with LED’s (194 base led bulb) here is what happens when you activate the turn signals when the headlights are off. When you activate either turn signal the opposite side DRL / hockey stick alternates from high to low (see YouTube video below). So I swapped the corner marker LED’s back to the incandescent bulbs and this issue stopped. I was going to install a pair of resistors to hopefully allow me to use the LED’s in the corner locations but haven’t had a chance to dig back into it.

 

Just thinking out loud here .... would one of those led harnesses from Radioflyer Innovations work ? I'm using switchback LED's and everything is perfect with the stock setup.

 

This is similar to the problem that I am having and I also have LED side markers. So now you gave me yet another experiment to try.
I have LED side marker lights in both the front AND rear. When you side that you put the incandescent bulbs back and the problem went away, you were only referring to the front side markers correct?

 

i also have red LED 194 bulbs in the rear quarter panel marker locations and they have never created a problem for me. It was just the front marker locations where the “gremlins” started to create issues.
Yesterday (4/5/19) I finally received my MoriMoto red led taillights and installed them. Luckily everything is working as it’s supposed to, including the front DRL’s.
It seems to me that the addition of the 6ohm 50watt resistors on then front turn signal circuits remedied everything. I attached a picture of where I mounted the resistor and the DRL/FTP harness for reference.

6ohm 50watt load resistor mounted to metal surface

DRL / flash to pass harness with added load resistor has remedied the issues I was previously having.

 

I am happy to say that since Bert posted the picture of his modified harness, I have modified one of the three different harnesses that I have (the one that looks like Bert's) to add the load resistors and my headlights finally work the way I want them to work. It took six months and many, many attempts at different things to get these headlights working.

 

Do you think this would work on the black potted harness?

This one

https://www.corvetteforum.com/forums...e-photo716.jpg

 

Can't tell which harness this is...there are many.
It looks like the first harness they came up with. To get this to work properly, you would need to add a diode to get the "flash to pass" to work and a load resistor to the directional circuit to prevent hyper-flashing.