LTZ led taillights problem

[pgamboa]

While a BCM Flash/Reprogram would correct it, like what @2017_WhiteZ71 said, dealers don’t do. This is a custom BCM program.

 

www.whiteautoandmedia.com does this but it requires you to take the BCM out (truck is down while it’s out), send it off and wait. Scheduling is involved too... so for that and the cost, most just add the resistor route.

 

 With that said, your resistors went bad and you probably replaced them with the incorrect ones.

 

 

Hey guys, Brand new to the forum tonight. I have been dealing with this "Hyperflash"  issue since June. I swapped my tailights out in January when I wrecked my 2015 LTZ and it was pre LED taillights so I bought the GM taillights and the bodyshop got a harness for them. I had the resistors for them to make them work and they worked for a few months and stopped in June.  I even changed out the resistors but still had the flash.   I was told I needed to have the BCM's  flashed, Is that correct? Or do I just need to double up the resistors ?

 

Any help is greatly appreciated, its been driving me insane!

 

 

  

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[dannonvoight]

I got off the phone with the staff at gen5diy.com and they said they don't do the 4 resistors anymore. They do x2 100 Watt, 3 omh for replacement. I just got some to try out and I will keep you guys posted ! Thanks for your help ! 

 

 

https://www.gen5diy.com/products/100-watt-3-ohm-load-resistor-upgrade

[BluEyeItln]

15 hours ago, 2017_whitez71 said:

You don't need the BCM flashed, no dealer would do that anyways.  As far a resistors go, you need one 3 ohm per side, or two 6 ohm per side.  

 

 

 

You guys got me thinking about mine now.  I have these (pictured) and they came with the attached device as well.  I only get hyperflash from one side usually when the battery dips.  I'm wondering if I connect two the same way you have these connected, maybe that would fix the issue.  Thoughts?  I'm hoping I'm on to something.

[RACERX7775]

19 hours ago, dannonvoight said:

I got off the phone with the staff at gen5diy.com and they said they don't do the 4 resistors anymore. They do x2 100 Watt, 3 omh for replacement. I just got some to try out and I will keep you guys posted ! Thanks for your help ! 

 

 

https://www.gen5diy.com/products/100-watt-3-ohm-load-resistor-upgrade

So they said its a single 100w resistor for each side. The link shows "comes with 2 sets". So, Is that 2 or 4.... wont they still get hot? 

[BluEyeItln]

21 hours ago, BluEyeItln said:

 

 

You guys got me thinking about mine now.  I have these (pictured) and they came with the attached device as well.  I only get hyperflash from one side usually when the battery dips.  I'm wondering if I connect two the same way you have these connected, maybe that would fix the issue.  Thoughts?  I'm hoping I'm on to something.

I have the company sending me additional diodes like the ones above.  I'll let you all know how that goes.

[pgamboa]

So they said its a single 100w resistor for each side. The link shows "comes with 2 sets". So, Is that 2 or 4.... wont they still get hot? 

Resistors get hot. I would imagine you’re getting (1) Pair, (2) - 100 watt, 3 ohm. Heck, PM me and I’ll get you a pair for 1/2 at a better price.

For rear tail lights, you’ll need (1) - 3ohm, 100 watt for each side. That’s what I use.


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[RACERX7775]

I guess for me ill only know if something goes wrong if both resistors fail. If one fails, the other will just get hotter, until that one fails and i get a lamp out note on the DIC. Atleast now i know what to replace them with WHEN they go bad.

[str8304]

On 10/12/2018 at 3:40 AM, 2017_whitez71 said:

Where do you get your resistors at?

Autozone

[dannonvoight]

21 hours ago, RACERX7775 said:

So they said its a single 100w resistor for each side. The link shows "comes with 2 sets". So, Is that 2 or 4.... wont they still get hot? 

1 per side. A total of 2 for the rear. 

 

[dannonvoight]

On 10/16/2018 at 11:39 PM, str8304 said:

Autozone

I got mine on Amazon 7$ for a pair 

[STRMTRPR]

.. has anyone ever investigated the flasher specs used on these trucks? I'm brand new to GM trucks (only had mine ~1.5 months) so not familiar with the flasher relay used.. most modern vehicles use an IC relay that incorporate a shunt resistor to sense the lamp current to determine which output mode to use - normal flash or hyperflash.. the value of that shunt can be altered accordingly to provide correct output mode, avoiding wasting the energy savings LEDs provide and converting this excess energy to heat via load resistors. Does anyone know what shunt resistance these trucks use in their flasher? Has anyone opened up the flasher and pulled the data sheet from the IC on the relay?

.. I'm not planning to convert to full LED on my truck.. just curious if this has been explored on these GM trucks already

 

*edit* the energy savings is admittedly more beneficial with a smaller motorcycle battery (I do run full LEDs on my bikes) vs a large truck battery but the same principal applies..ie. you could run your hazard flashers substantially longer for example

[STRMTRPR]

.. so as I was curious I did some digging and it appears that there is no external flasher module in these trucks and the functionality resides completely in the BCM.. overcomplicated way of doing it but I'm sure it saved GM a couple $ in production

[2017_whitez71]

So I am confused.  I know i can use 1 3ohm 100w resistor for my led taillights.  However can I use 2 6ohm 100w resistors instead?  

[pgamboa]

.. so as I was curious I did some digging and it appears that there is no external flasher module in these trucks and the functionality resides completely in the BCM.. overcomplicated way of doing it but I'm sure it saved GM a couple $ in production

Correct. All handled by BCM in these trucks.


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[BlkSS]

2 hours ago, STRMTRPR said:

.. so as I was curious I did some digging and it appears that there is no external flasher module in these trucks and the functionality resides completely in the BCM.. overcomplicated way of doing it but I'm sure it saved GM a couple $ in production

 

Just something to think about here...

 

It's actually a relatively simple way of doing things.  I also highly doubt it was about saving a couple dollars as well. 

 

They've had BCMs for this for over a decade now at least.  With today's vehicle communication networks (LIN, CAN, FlexRay, etc), they are able to do everything that they do and do it efficiently.  There are less modules and wiring that have single uses.  The weight savings alone from this is tremendous.  

 

This also simplifies diagnostics as long as you have a way to communicate with the vehicle.  If you don't have the ability to communicate, it's going to cost you by either gambling on parts or paying someone else to fix it. 

 

In my opinion, if you have any inclination of working on your own vehicle of today, I highly recommend buying a bidirectional communication scan tool and possibly the J2534 programmer. 

 

People complain about the cost to repair today's vehicles but have no idea what it takes to properly diagnose them or where to begin sometimes.  Also,  to solve a common misconception, scan tools don't tell you what is actually the cause of the problem, they just help point you in the direction of the problem.