Signals in mirror flicker when high beams are flipped on

[holty]

I have an 08 Sierra with oem dl3 mirrors. When I hit my high beams on the little lights in the side mirrors flicker on momentarily. What could cause this? All stock bulbs

 

 

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[citydriver]

A worn Multifunction (turn signal) Switch, dirty BCM (Body Control Module) ground is a possiblity. Or you may just be hitting it on an angle when you turn on your high beams.

[citydriver]

Now that I'm thinking about it, if you had a bad BCM ground, you would have multiple issues. That thing controls alot. I'm leaning more towards the switch being worn or possibly just hitting the lever on an angle.

[holty]

Hey thanks for the reply! I"ll check the turn signal switch or just replace it, but i want to add a few more details about my problem. First, this problem JUST started happening after removing the headlight assemblies. I had a burned out low beam so i replaced it and put it all back together. Now when i flip my high beams on the signal mirrors flicker on and if i'm driving down the road they continue to flicker like something is loose somewhere. ALSO, now i have a message that pops up on my DIC that says the hood is open, but it quickly goes away. That happened twice this morning on my 40min commute to work. I pulled both headlight assemblies again, checked and rechecked all the connections on all of the bulbs. I even put another set of bulbs in, high beam bulbs, turn signals and marker lights. Problem still there. I know this problem started right after replacing the low beam but i just can't figure out what i did to cause it? I even replaced the headlight assembly wiring harness on both headlight assemblies. This harness is where all the bulbs plug into and is attached to each headlight assembly. Could I have a bad harness to the BCM?

[txab]

Just for the heck of it, check battery, battery cables and their connections. Also check ground connectors.

[holty]

The battery is the OEM ACDELCO i do believe. It probably needs replaced but its working fine, truck always cranks and starts with no problem.

The battery grounds are connected to the engine block and the frame. Both connections are tight, i didnt remove them at all. I suppose i could remove them and replace them just to be sure.

 

WTF would cause the "hood open" message to appear!!! LOL i know the damn hood is shut completely. LOL this is driving me crazy....

[MikeNH]

I would make totally sure you haven't managed to pinch a wire somewhere. The hood message indicates there must be a switch on the latch somewhere you can check as well.

[holty]

anyone else?

[becker87]

My head lights do the same thing when my G-80 kicks in. I think it is just the battery sending juice elsewhere momentarily. If the truck had a capacitor I think it would solve this.

[holty]

My head lights do the same thing when my G-80 kicks in. I think it is just the battery sending juice elsewhere momentarily. If the truck had a capacitor I think it would solve this.

 

can you ellaborate a little more on what you're saying here? what do your headlights do exactly when your G80 kicks in?

[kstruckcountry]

My head lights do the same thing when my G-80 kicks in. I think it is just the battery sending juice elsewhere momentarily. If the truck had a capacitor I think it would solve this.

No power to G80. It's mechanically operated.

 

OP, it sounds like you're shorted out somewhere. When the mirror lights flicker, do your turn signals in the front or rear flicker as well?

[holty]

No power to G80. It's mechanically operated.

 

OP, it sounds like you're shorted out somewhere. When the mirror lights flicker, do your turn signals in the front or rear flicker as well?

We know there is no power to the G80, i'm assuming that he meant when the traction control kicks in the headlights dim, mine has always done that too.

 

I think i'm shorted out somewhere also. No other lights flicker other than the mirrors, that i can tell.

[MikeNH]

My head lights do the same thing when my G-80 kicks in. I think it is just the battery sending juice elsewhere momentarily. If the truck had a capacitor I think it would solve this.

 

 

Your headlights flicker because the ABS/traction control module is drawing power as it slows wheelspin. The G80 uses no power.

[becker87]

No power to G80. It's mechanically operated.

 

OP, it sounds like you're shorted out somewhere. When the mirror lights flicker, do your turn signals in the front or rear flicker as well?

Thanks for the clarification guys. Makes a bit more sense now!!

[holty]

Update, here is a video of the issue happening. Really starting to get annoying. Any ideas what would cause this?