Reprogramming 2007+ BCM for LED lights

[Gone Nomad]

I searched for a definitive answer on this, and came up empty handed.

Here's what I know:

2007+ GM trucks and 2008+ GM vans use the BCM to flash the turn signals instead of a flasher relay. The BCM checks for burned-out turn signal bulcs by measuring the load, and uses a "fast flash" to notify the driver that a turn signal is burnt out. GM (and presumably every other manufacturer) had to do this because of this government mandate:

"A standard production vehicle will have BCM software that checks for two bulbs functioning in each rear turn signal bulb circuit. If one or more bulbs are inoperative, the BCM will “fast flash” the Instrument Panel Cluster (IPC) turn signal indicator as required by Federal Motor Vehicle Safety Standard (FMVSS) 108 and Canada Motor Vehicle Safety Standard (CMVSS) 108." (from GM Upfitter BULLETIN # 81)

Apparently, at least some newer models also use the BCM to check for other burned-out bulbs besides turn signals (by measuring the load), including (apparently) dome lights. I guess in these models, an error message shows up on the DIC?

All of this is a problem for anyone who wants to replace the oem incandescent bulbs with the far more efficient LED bulbs (which are now readily available in a wide variety of sizes, brightness and colors, for very affordable prices) because they draw so little current (load; amps) that the BCM "thinks" the bulb is burnt out.

The most common solution is to use so-called "CANBUS" LEDs, such as these Superbright "CAN BUS" LEDS which add a load resistor to mimic the (much higher) load of the oem incandescent bulb that the BCM expects. Of course, while adding a load to "trick" the BCM should work well enough, it also defeats one of the main advantages of LEDs: drastically lower power consumption.

The better solution is in the same GM Upfitter Bulletin #81, which mentions that the BCM can be reprogrammed to turn off "bulb outage detection":

"In some cases, the upfitter may wish to change the turn signal bulb outage detection capability so that the turn signals work correctly with their upfit or to meet certain requirements. This will require contacting the Techline Customer Support Center to open a case and obtain a Vehicle Configuration Index (VCI) number. Advise the TCSC consultant which turn signal bulb outage detection capability is needed:
1. Factory standard production TWO bulb outage detection.
2. Optional (RPO 9U5) ONE bulb outage detection. NOTE: ONLY AVAILABLE ON CERTAIN 2008 MODEL 2500
AND 3500 VEHICLES
3. NO bulb outage detection (LED compatible).
The BCM can then be reprogrammed with the correct software."
(from GM Upfitter BULLETIN # 81)


Here are my unanswered questions:

Has anyone actually been able to get their BCM reprogrammed to turn off "bulb outage detection"?
Did you have to get as dealer to do it, or is it possible for someone who has a Tech 2 to do it, if they know how?
If you had to get a dealer to do it, how many hoops (if any) did you have to jump through and how much did they charge?

The part about "This will require contacting the Techline Customer Support Center to open a case and obtain a Vehicle Configuration Index (VCI) number."
makes me think it probably isn't so easy to do this.
...but maybe the same type of people who have figured out how to unlock & bypass the VIN-lock on oem GM radios have also solved this problem too?


Any links to existing threads that do more than mention the possibility of reprogramming the BCM to turn off bulb outage detection would be greatly appreciated.

Thanks!



refs.: GM Upfitter BULLETIN # 81
http://www.dieselplace.com/forum/76-gm-trucks/81-electrical/411169-load-resistors-good-idea-bad.html
http://www.dieselplace.com/forum/76...ght-turn-signal-led-bulb-install-problem.html

 

[THEFERMANATOR]

The bulletin you mentions is basically saying GM dealer only. You have to call in and have them do a custom BCM flash for your truck, then they can at the dealership flash in the new factory calibration. Not sure if they will do this for a regular truck or not. I know they will if you have a service bed or something along those lines though.

 

[chevyburnout1]

You may be able to say your going to get a service bed installed next week and they could call GM TAC. I couldn't see why not. But I know some dealers are iffy when it comes to thinking out of the box.

 

[Gone Nomad]

The bulletin you mentions is basically saying GM dealer only. You have to call in and have them do a custom BCM flash for your truck, then they can at the dealership flash in the new factory calibration. Not sure if they will do this for a regular truck or not. I know they will if you have a service bed or something along those lines though.

That's what I figured it meant (unfortunately). Thanks for confirming the bad news.

You may be able to say your going to get a service bed installed next week and they could call GM TAC. I couldn't see why not. But I know some dealers are iffy when it comes to thinking out of the box.

Unfortunately it's actually a van, so that explanation probably won't fly.
And if my past experience is any guide, I'm pretty sure I won't find a dealer that will do any more than the bare minimum they are required to do (more likely they will cut any corner they can), especially since I didn'y buy my van from any local dealer (because they wouldn't be bothered/couldn't find what the DMax van I wanted, I had to buy it over 500 miles away).
I do not have a "connection" with any local dealer. I had one until GM closed that dealer down several years ago.

The van electrical manual (from GM upfitter) states this:

If upfitters can do it, then maybe that's even easier? Maybe that's better... maybe this calibration is more readily available?

One thing I'm not clear on is: is the "LED Lamp calibration" a complete BCM calibration file that affects everything else controlled by the BCM? ...or is it possible to just change the lamp calibration within the existing BCM setup. IOW, does it work more like the way EFILive works with the ECM, where you can choose which individual attributes can be changed without overwriting everything else? Or does the Tech 2 only have the capability to replace the entire existing BCM calibration with another?

All of this stuff that GM and the other automakers do... which appears specifically intended to make it more difficult for end users to fix simple problems or many even minor changes, just makes them look like they're desperate or something... and makes end users (justifiably) feel like they're getting gouged. I ran into this when I wanted to upgrade the radio. But the guys selling upper-level oem radios have evidently figured out how to bypass the VIN-locking scheme. I guess the BCM cals. aren't so easy though.

 

[chevyburnout1]

The BCM I believe has the same "partial flash" and "full flash" capabilities. 95% of dealer flashes are just partial or calibration flashes. If you were to get this calibration flashed in more than likely the LED lights will be the only parameter different out of the whole operating system. Wouldn't hurt to just stop by the dealer and tell them what you would like to do. Mentioning a bulletin number helps out as well.

 

[THEFERMANATOR]

From what you describe in the bulletin, it sounds like all they have to do is connect to the MDS(I think that is what they call the flash portal), and go in and select BCM programming, then select the avalaible options. They do give some options for factory add on features in the menus for BCM programming. When I did my swap I had them program it to a work truck cal and select no options to minimize codes the BCM would set. It took less then 30 minutes to hook it up, go through the menus and select the options, and then flash it in. They normally charge you a standard hour for any flash at most dealers.

 

[Gone Nomad]

Thanks, guys.