# Fog & Aux. Lights no go



## RepoMan207 (Oct 7, 2008)

Has anyone had any problems with there Auxiliary lights and Fog lights not working?

I checked the Fuses on the indicated fog light, and SEO 1 which is the auxiliary power for those lights....not sure how to check the Fog light relay other then by replacing it.

The other odd thing is my Light Reminder Chime stopped working. I know it's not the buzzer because the Key Reminder Chime works just fine...seems to me the lights automatically went off even if I left them in the manual on position. 

This all happened in the last week, and yes I changed out the bulbs. 

2002 GMC Sierra 6.0 SLT


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## RepoMan207 (Oct 7, 2008)

Nobody? Bumpity bump bump


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## Q101ATFD (Oct 24, 2006)

I am pretty sure the Aux lights are on the SEO 2 fuse, from Post 2 in the underhood electrical center. Should be a 30A fuse.


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## ahoron (Jan 22, 2007)

First Check the switch connector Do you have power to the 86 terminal on the relay? If not I would think bcm


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## RepoMan207 (Oct 7, 2008)

Q101ATFD;814791 said:


> I am pretty sure the Aux lights are on the SEO 2 fuse, from Post 2 in the underhood electrical center. Should be a 30A fuse.


It shows SEO in the manual, but I did check it just the same.


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## RepoMan207 (Oct 7, 2008)

ahoron;814821 said:


> First Check the switch connector Do you have power to the 86 terminal on the relay? If not I would think bcm


I am going to check this tongiht.


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## RepoMan207 (Oct 7, 2008)

No power to the relay slots.....Now what?


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## B&B (Nov 4, 2006)

You should have 12V in one of the relay slots and a second one showing as 12V with the park/headlights on.

1) Did you verify that you have 12V on BOTH SIDES of the 15 AMP fog fuse?

2) Did you check for ground on the black wire(s) directly on the fog light bulb sockets?


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## RepoMan207 (Oct 7, 2008)

B&B;816116 said:


> You should have 12V in one of the relay slots and a second one showing as 12V with the park/headlights on.
> 
> 1) Did you verify that you have 12V on BOTH SIDES of the 15 AMP fog fuse?
> 
> 2) Did you check for ground on the black wire(s) directly on the fog light bulb sockets?


I'll check it out this afternoon, and get back with you.


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## RepoMan207 (Oct 7, 2008)

I finally had a chance to get back to this today. I injured my foot Friday night so I am under orders from the doctor to "take it easy for the week" interpreted by me as "Get caught up on the things I have been neglecting". 

Mike, I lifted both covers off that fuse panel after removing the fender support, minus the dust it looks brand new under there. The washers are still gold tinted and everything. To be thorough, I went ahead and physically checked every wire in every connector and followed each one out of the housing area as far as I could. Nothing out of sorts at all. I noticed today the little light next to the fog light switch doesn't light up anymore. I think I am going to go ahead an pull that tomorrow morning and test the wires going to it. Any other suggestions or direction that I should be trying?


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## B&B (Nov 4, 2006)

Good to hear the underside of the panel is ok as they have an issue with accumulating corrosion as these trucks age. Now you know that at least that part of it is a-ok. Next, head back to the fog relay sockets with your trusty test light. I know you checked a few all ready but you need to dig a bit deeper to see if the relay is receiving it's ground signal from the BCM as that's how the relay is activated. 

One socket should have constant 12V
One should show 12V with the park/headlamp switch in the "on" position
One will show nothing as it's the output TO the fogs...
The last one is what you're after. It's the ground trigger from the BCM. While you hold the test light in there (with the other end connected to 12V of course) press the fog light button to see if the ground is there. Again make sure the park/headlamp switch in in either the park or headlamp position.

Let me know what you find and if it doesn't check out we'll back track through the system from there.


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## RepoMan207 (Oct 7, 2008)

Ok, here is my results from today.


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## B&B (Nov 4, 2006)

Is there 12V on the orange wire with the ignition and park/headlamps on, and then 12V on the purple when the fog switch is on?


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## RepoMan207 (Oct 7, 2008)

There is no juice on the orange at all, I take it there is supposed to be? (I'm a bit color blind, but the orange to me is the second one in from the right? More pink to me, but you get the idea). I did this test with the lights in the on position, with the fog & cargo lamp switch disconnected from the harness all together. I'll pull it again today and probe just the wire itself this time, alternating with the fog switch on. If a positive current isn't detected; should I try throwing a current to it and see what happens?


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## B&B (Nov 4, 2006)

Ok, first check the black wire for ground. If it has it- then take a 5 AMP fused jumper wire and connect the orange and the black wire together at the fog switch connector while the park lights are on. Do the fogs illuminate?


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## RepoMan207 (Oct 7, 2008)

...............:whistling::whistling::whistling:..........

Oops! Yeah, so part one complete, ground is good. Part two.....ehhh, not so much. I kinda overlooked the part were you said use a FUSED jumper when testing the black to orange. I got side tracked just before going out to the truck, by the time I got back around to it I some how mis construed it to mean use a fused jumper when checking the ground instead, and you guessed it, finger happen to slip while holding the little 16 gauge wire to the orange socket, then landing in the end socket where the juice is. 

Now I don't have any instrument lights :realmad:. If I spin the dimmer switch all the way up, like I am turning the interior lights on, the instrument & dash lights will come on though. I looked everywhere for a blown fuse, I couldn't find one. I suspect I fried the dimmer switch which is part of the headlamp switch, but would the top section work if the dimmer were fried, wouldn't it be more likely an ign. source at that point?.?

Anyway, with the dial all the way up and the lights on, I tested the sockets on the connector, juice was present again on that end wire, so I continued on with part two, the fog lights didn't come on.


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## B&B (Nov 4, 2006)

Ugh. If you're 100% positive that you have no blown fuses then you either smoked the headlamp switch....or the BCM. And unfortunately the fact that afterwards jumping the black and orange wires didn't turn the fogs on makes it highly likely that you smoked the BCM, because thats the signal to the BCM to activate the fog relay...and it didn't do so. 

On these late model vehicles you can not fool around haphazardly when it comes to the wiring systems as you're dealing with very sensitive and sophisticated systems that won't tolerate a dead short so it's imperative to heed all tips and warnings and be both knowledgeable and accurate in what you're doing...or you will cause more issues than you solve. Looks like you discovered that the hard way.


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## RepoMan207 (Oct 7, 2008)

Yeah, no fuses blown. I not only narrowed it down to the Ign.1 fuse, but went and tested every single fuse in the truck using a tester. 

Is the BCM compartmentalized, meaning, if it is in fact damaged, is there more symptoms to come, or is this it? What is the procedure for replacing it? If it's what I think it is, It's just under the dash to the right of the steering column? It looks to be nothing more then an over sized plow module. Is this something that a dealer or trained tech has to do, or is it a plug and play thing?

I had it too, and when nothing happened I thought to myself "well, maybe it's not getting good enough contact", just as I readjusted, my fingers cramped up & thats when it happened. I learned the hard way is right. I appreciate all your help Mike.


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## B&B (Nov 4, 2006)

If it is damaged, whatever state it's in now it will stay. In other words, whatever components aren't working or functioning correctly will stay that way and it shouldn't effect other systems.

In your case a BCM replacement will need to be done by either the dealer or someone with a Tech2 scanner as it needs to be manually re-synced with the other modules in the truck on the network or else the truck won't start due to the security system not recognizing the new BCM. 

No good news or instant fixes for you I know, but that's how it works some days.


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## RepoMan207 (Oct 7, 2008)

Well, thanks again for all our help. I'll let you know the end result once I get her in to the shop. :waving:


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## RepoMan207 (Oct 7, 2008)

B&B, whats the word on using used BCM's? I located a dealer nearby with a new one on the shelf, but of coarse I have the most expensive one...$430. The local LKQ has a couple used ones as well. I matched the part number to be sure, but the dealer is saying I can't install a used one. Any insight on this?


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## B&B (Nov 4, 2006)

Well, technically you can use a used one but you'll have to have it at the dealer so they can flash it to your truck as it won't run until you do. And of course a dealer isn't going to flash a used one, only a new one that they'll of course be more than happy to sell you. payup

A catch 22 more or less.


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## RepoMan207 (Oct 7, 2008)

Sweet, thanks. A buddy of mine is a lifetime FORD tech gone solo. I know he has the Tech2 tool as my brother uses it now and then. Is that what they use to "flash" it with?


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## B&B (Nov 4, 2006)

If you have access to a Tech2 then you're good to go.


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## RepoMan207 (Oct 7, 2008)

Awesome, thanks once again!


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## RepoMan207 (Oct 7, 2008)

So my new BCM finally came in yesterday, I met my brother over to my previously mentioned friends garage that has the computer to "zap" it with. By some grace of god the BCM was fine after all, none of the lights came on for us. We "borrowed" a light switch from a unknowing customers truck that is similar to mine to see if that would work, all the lights came on! The Light switch was the culprit. I must have injured it further when I shorted those wires and blew the dimmer side of it. I ordered a new light switch for $52, should be here by the end of the week. 

Of coarse once one thing is fixed (or near fixed) another breaks...I got home and locked my truck as always do, but my passengers side actuator isn't locking the door. Yet another project for another day.


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## B&B (Nov 4, 2006)

Good to hear its fixed Ryan but it doesn't add up. If you jumped the orange and black and the lights still didn't illuminate that takes the switch out of the equation, because by jumping those two wire your bypassing any functions the switch provides. Strange one indeed.


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## RepoMan207 (Oct 7, 2008)

I must not have been getting enough contact or something. Are you thinking the BCM & the switch were both gone? We didn't put the old BCM back in as I had to return one of them anyway for the core charge, and there was a notice about no returns on electric parts...Couldn't see not using the new one anyway.


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## B&B (Nov 4, 2006)

RepoMan207;883218 said:


> I must not have been getting enough contact or something. Are you thinking the BCM & the switch were both gone?


That's what it had to be, the switch and BCM both. The switch was probably fine until...umm, well you know.


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## RepoMan207 (Oct 7, 2008)

:whistling: :whistling: I can assure you...I don't know what your talking about. :laughing: 

Thanks again for all your guidance on this...even if I did botch it along the way.


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## RichG53 (Sep 16, 2008)

That's how you learn ...(Mistakes).....

If you never make another mistake ...You will never learn a thing......


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