L.e.d Taillights On 07 Sd = Problem

[GMCRB]

I purchased a set of these on ebay. They fit and look great. The problem I have is when you put the turn signal on they blink normal 3 times and then blink real fast. They have the little black boxes attached to them that I am told are resisters to keep this from happening. Anyone have a fix for this?

[dlewis1111]

I purchased a set of these on ebay. They fit and look great. The problem I have is when you put the turn signal on they blink normal 3 times and then blink real fast. They have the little black boxes attached to them that I am told are resisters to keep this from happening. Anyone have a fix for this?

 

Assuming 07 NNBS here: There was some verbage in the upfitter books about aftermarket LED's causing a specific problem with the lighting system. I will look and see what I can dig up. And yes, the resistors are there to maintain the resistance that the truck is looking for so that it doesn't think you have a bulb(s) burned out. Looks like your rig thinks your bulb(s) are inop. Does it do it on both sides? You may need to add some inline resistors to fix the problem. I was in the process of adding LED bulbs myself when I discovered that I would have to add multiple resistors in the system and the cost (I found some prewired inline resistors that were really easy to put in) was not worth the results.

[dlewis1111]

From the 08 electrical upfitter manual - red highlights talk about the LED's. Your truck is doing what it is supposed to because the BCM thinks there are bulbs out. No flasher in these trucks to change out to control blink rate. To fix this, you need to have your truck calibrated like it was a bed delete option using service bulletin 1956334. Basically, this sets the BCM to blink at a set rate and disables the bulb outage detection. I had not even read this until searching for you, I may check back into adding LED bulbs again.

 

 

 

Electrical Manual – 2008 Light Duty Full Size C/K Trucks PAGE A-72

 

Service Body Rear Lighting Options (including LED)

Service Body Lighting Options (including LED)

Models Affected: All New C/K Chevrolet Silverado and

GMC Sierra, 3500 Series Heavy

Duty Chassis Cab, Pickups with Box

Delete Option (RPO ZW9) and,

Models Approved for Pickup Box Removal

SUMMARY

• Chassis Cab & ZW9 box delete option models will work

with LED or any other turn signals without modification.

• Tail lamp alteration of a regular truck (i.e. deleting Pickup

box w/o ZW9) needs to have the BCM calibration

changed if LED's or single bulb lamps are used. This

must be done at a dealer.

Service Bulletin (Document ID# 1956334) describes how the

dealer can change the BCM calibration.

Notes: This bulletin addresses the "All New" not the

"Classic" C/K truck.

FMVSS 108 / CMVSS 108 compliance is the responsibility of

the upfitter.

Significant points are as follows:

• The Turn Signals are controlled by the BCM not

a separate flasher module.

• Rear Lamp Bulb Outage detection is displayed as a

"fast" turn signal flash rate in the cluster.

• All trucks are built with one of two BCM calibrations:

¤ All "regular" C/K trucks - 2 Bulb Outage Detection

¤ All Chassis Cabs & ZW9 box delete option –

No Bulb Outage Detection. This may be used for

LED turn signals with a standard flash rate.

¤ Note: No calibration presently exists for Single Bulb Lamp

Outage Detection.

• The BCM is current limited to 6A. The BCM output

(& lamps) will turn off if this is exceeded.

• The "All New" C/K trucks have combined "red"

stop/turn signal lamps.

• Adding additional turn only (Amber) signals are

described in the Body Builders Manual.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some

vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and knowhow

to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See

your GM dealer for information on whether your vehicle may benefit from the information.

The address of the UI Bulletin #81 (and the accompanying Upfitter

addendum #07-08-442-006) is:

http://www.gmupfitter.com/publicat/bull/63...letin_81_D3.pdf

This copy excerpted

[700 sportsman]

if you go to superbrightleds.com, they have several resistors that can be wired in, or an electronic flasher, instead of a thermal one. They also have some information on the issues your having

[dlewis1111]

07 - 10 dont have any type of flashers - the bcm is programmed to monitor the circuit for resistance thus indicating bulb outage.

 

Oh, and does your cruise control work? If your truck senses a bad rear bulb, it may have disabled the cruise control. The load resistors are 3.95 to 4.95. And you need one resistor per bulb.

 

I think that it's time to contact the ebay seller and get your money back or trade them out for a set that works. If they had built in resistors, this would not be a problem.

[700 sportsman]

Hmm, that's interesting that they don't have a traditional flasher.

[dlewis1111]

Hmm, that's interesting that they don't have a traditional flasher.

 

technology - aint it great!

[Riverjet502]

So this wouldn't be a problem on a 2004 then correct? The way I am reading this post?

[dlewis1111]

So this wouldn't be a problem on a 2004 then correct? The way I am reading this post?

 

Truthfully, I am not sure. I am not familiar with that year model. I do know that vehicles with traditional "flashers" also sense when there is a drop in resistance to indicate a bulb being out. That said, in theory, you would need the same resistors as the newer ones. -OR- A new flasher that compensates for the drop in resistance. I have purchased several LED bulbs from http://www.ledlight.com and they have several flasher modules listed to replace factory versions to correct this problem. Their tech department is really good, I would give them a call.

 

Click here!

[jrrod2004]

So this wouldn't be a problem on a 2004 then correct? The way I am reading this post?

 

Truthfully, I am not sure. I am not familiar with that year model. I do know that vehicles with traditional "flashers" also sense when there is a drop in resistance to indicate a bulb being out. That said, in theory, you would need the same resistors as the newer ones. -OR- A new flasher that compensates for the drop in resistance. I have purchased several LED bulbs from http://www.ledlight.com and they have several flasher modules listed to replace factory versions to correct this problem. Their tech department is really good, I would give them a call.

 

Click here!

 

 

 

Yeah, the 2006 that I got did the same thing so I simply wired in a thermal resistor (parallel) and it took care of the rapid flashing...

[TexasAl]

If the truck has a traditional flasher, you need an electronic flasher that has a circuit board inside that will work with a small load (like LED lights).

[dlewis1111]

If the truck has a traditional flasher, you need an electronic flasher that has a circuit board inside that will work with a small load (like LED lights).

 

That is what I was referring to in my earlier post. I saw a bunch listed at ledlight.com and like I said, their techs were really good.