Whelen WigWags in 2002 Avalanche

c17loadsmasher · Post by **c17loadsmasher** » Sat Feb 21, 2004 4:50 pm

Just out of curiosity, has anyone tried to install a Whelen UHF2150A headlight flasher in a 2002 Chevy Avalanche? A friend and I were contemplating puting one in his Avalanche. I know these newer vehicles are wired a little weirdly. I installed the one in my 2002 TrailBlazer that I had asked about a few weeks ago, and everything is fine. Anything I should know about regarding the Avalanche? Any information would be most appreciated.

Thanks!

jim · Post by **jim** » Sat Feb 21, 2004 9:12 pm

The Avalanche is basically a carryover of many components (including wiring) from the pickup line. The 98-early 03 uses a system that switches BOTH the negative and positive sides of the high beams. With the OEM schematics, one with good auto electric experience can figure it out. Be careful though.....it's easy to backfeed the BCM in this system. You must isolate the lights from the system totally and switch over to a true positive switching configuration for this to work properly. You will need to fab an entire harness for the 2 high beam lights with a Bosch relay for proper isolation. (ooooops! I swore i'd never give any info on this, although it's only a little!). You will use a standard positive type wigwag unit.

nmfire10 · Post by **nmfire10** » Sat Feb 21, 2004 9:25 pm

I know in the minds of the automotive engineers, these systems have their advantages. But I have to wonder if they can see people like us cursing them up and down over it and they laugh.

FFParamedic571 · Post by **FFParamedic571** » Sun Feb 22, 2004 5:54 am

Jim,

I totally avoid the subject. I tell the customers it can't be done and sell them hideaway strobes... Its lazy but it works, in the long run by the time you wire up the relay and diodes it cost the same as a basic kit..

jim · Post by **jim** » Sun Feb 22, 2004 8:03 am

I totally agree, but there are just some people that insist upon having these things! Once they find out how much is involved, they usually run, but there's always that one wacker that "needs" them and are willing to pay 2 hours labor just to have them because nobody else does.

Halogen or strobe inserts take 1/3 the time, although they are not as intense.

FFParamedic571 · Post by **FFParamedic571** » Sun Feb 22, 2004 9:47 am

I think we shoud charge a " whacker" fee... any Yahoo who wants lights and siren in a oddball car for his security/react/guard dog job..everything costs double +20%...

c17loadsmasher · Post by **c17loadsmasher** » Sun Feb 22, 2004 11:19 am

Just to clarify, it's not for some security/react/guard dog job. It's for responding to calls with our fire department. Thank you for being so understanding.

DFD565 · Post by **DFD565** » Mon Mar 22, 2004 12:59 pm

Galls has a flasher that will do what you need get the FS0004.

jim · Post by **jim** » Mon Mar 22, 2004 4:08 pm

The FS0004 is NOT the correct flasher for the Avalanche or trucks of that year. These are NOT ground side switched.

Put it in and guess what? You turn it on and have no wigwags!These trucks switch B-O-T-H negative and positive. Read several posts above.

DFD565 · Post by **DFD565** » Tue Mar 23, 2004 9:12 am

would you say that the fs0005 is the correct flasher for a 2000 suburban

jim · Post by **jim** » Tue Mar 23, 2004 9:02 pm

If the 00 'Burb's wiring is carried over from the pickups, they also have the dual-switched system.

That flasher will work, but you must add a relay to feed B+ to the headlight circuit whenever the wigwags are on. Also, must be isolated from the PCM.

DFD565 · Post by **DFD565** » Wed Mar 24, 2004 6:27 am

i'm in the middle of building a plug in harness for this flasher to put in my 'Burb..so i dont have to cut factory wires just plug it in....the instructions don't show that both are switched(link below to instructions and rough schematic for light system) ...do you have a schematic of the headlight system for these Burbs....don't want to make a costly mistake....and we are required by our Dept. to have wig-wags and 360 warning...else i would use other.

http://www.galls.com/documents/FS005_3- ... th_DRL.pdf

jim · Post by **jim** » Wed Mar 24, 2004 6:32 am

Just find which of the 3 headlight leads is B+12V when the lights are on. Add a relay to power this same lead up whenever the WW switch is pressed. You could also switch the OEM relay that does this, but it's easier to add your own.

If you get any error lights on the dash, the diode will have to be added.

DFD565 · Post by **DFD565** » Wed Mar 24, 2004 7:58 am

i've looked back at my notes here from planning this what it looks like is happening with this installation is of the Two high beam leads the positive is coming into the flasher and is passed through flasher, the light bulb itself is powered by the flasher. so in theory when the high beams are on the flasher doesn't operate even if powered. but when powered and headlights are off it controls the lights ......the flasher is sitting in between the switch and lights not tapped into them along side. catch my drift ....at least this was my understanding.....but this came from reading the instructions. ..which are wrong now and again.....this is making me rethink this projects simplicity...... I need to do some homework on this....just found out that there are multiple wiring configurations based on vin....could be same for avalanche.....since its a Burb with bed and tailgate

Mike in CT · Post by **Mike in CT** » Wed Mar 24, 2004 5:22 pm

I mantioned it before...

the GM wiring is so strange, it is MUCH easier to simply install a set of hideaway strobes instead of trying to flash the headlights.

My 99 Suburban was so much of a pain in the butt, that the shop did just that, installed clear hideaways in the front clear lenses... works great.

It just wasn't worth the time and uncertainty to try to put in headlight flashers. (seems the DRL module wasnt where it was supposed to be either... but thats another story).

And the folks I work for basically have unlimited funding!

To keep ME happy, they labeled the wildcard box to say "WIGWAG"

73,

Mikei n CT
KM1R

apco25 · Post by **apco25** » Wed Mar 24, 2004 6:32 pm

What I don't get is why would Gm use multiple different wiring schemes in the same family of trucks or even within the same model?

In my opinion this defeats the purpose of having standardized parts and wiriing for the various vehicles.

007 · Post by **007** » Wed Mar 24, 2004 9:23 pm

The BCM in my Impala can bite me...I hate it. Grrrrr...

Figures...it's made by /\/\

jim · Post by **jim** » Thu Mar 25, 2004 6:45 am

The reason they do this is that from the dashboard forward, the trucks and SUVs are pretty much the same. They use this part of the harness and add it to a rear section of the SUV harness.
They only have to produce 1/2 of a harness and just join it with the other 1/2 section that's already in production anyway.

GM= inexpensive, cheap, make HUGE profits! I'm sure GM makes more $$ than the "other two." This is one way they can do this.

DFD565 · Post by **DFD565** » Thu Mar 25, 2004 11:25 am

yeah strange that they would do this..... i have two 2000's one silverado one Burb. both are same ....neighbor has '00 silverado stripped down version has different wiring...strange. checked last night, our ambulance has '00 suburban "Fly Car" that has different wiring to high beams than mine......what is GM doing........

apco25 · Post by **apco25** » Thu Mar 25, 2004 3:58 pm

Am I missing something here? If they keep changing all the wiring harnesses and schemes how does that cost them less money?

jim · Post by **jim** » Thu Mar 25, 2004 9:05 pm

They don't keep changing them. When a new vehicle comes out, rather than building an entire new harness, they use a large part of an existing harness and add whatever else is needed for the new chassis. Adding 10% to an existing harness is cheaper than redesiging a new one from the ground up.

Many times, they just add a second "plug 'n play" harness as a supplement to the main existing harness to avoid even having to do anything at all with the old one.

c17loadsmasher · Post by **c17loadsmasher** » Fri Mar 26, 2004 7:21 am

We gave up on the Avalanche....I do find it odd however, that the wiring system for the Avalanche is so different than the one for the TrailBlazer which I currently do have wig-wags in...with no problems. I assume there is some logic to GM's madness. You can't really expect them to design a wiring harness with the sort of modifications that we do to it in mind...

apco25 · Post by **apco25** » Fri Mar 26, 2004 2:50 pm

well it just seems like poor engineering design and subsequent maintenance to just extended an existing harness.

I wasn't even commenting on the particular needs of emergency equipment

Whelen WigWags in 2002 Avalanche

Whelen WigWags in 2002 Avalanche

wig wags