What did you do to your NNBS GMT900 Tahoe/Yukon Today?

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the_tool_man

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when the drl is on it is at slightly lower voltage than when it is in headlight mode. that could be a potential problem alone depending on the bulb used.
I am not sure of the voltage but I would guess probably 10v for drl and 12 when headlight. when it switches modes you can hear the relay click over
Thanks for the information. That gives me something to test.
 

the_tool_man

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Thanks for the information. That gives me something to test.
It gets better. I manually turned on the headlights in the dark. Passenger side low beam is on normally. Driver side low beam and both highs are very dimly on. High beam is switched off. There's definitely a wiring issue somewhere!
 

Doubeleive

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It gets better. I manually turned on the headlights in the dark. Passenger side low beam is on normally. Driver side low beam and both highs are very dimly on. High beam is switched off. There's definitely a wiring issue somewhere!
swap bulbs left & right and rule the bulb in or out.
 

j91z28d1

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they are aftermarket housing right? do the factory bulbs and sockets just plug in or is there aftermarket wiring involved inside?

just wondering if some sockets or plugs overheated and making a back connection?
 

the_tool_man

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they are aftermarket housing right? do the factory bulbs and sockets just plug in or is there aftermarket wiring involved inside?

just wondering if some sockets or plugs overheated and making a back connection?
They are aftermarket units. They plug into the factory bulb sockets and are internally wired from there. The DRL and low beam circuits must be joined because the low beams are single-filament bulbs. This weekend I'll pull everything apart and diagnose it. I'm hoping there's a short in one of the housings that's causing the issue. That'll be easier to fix. Maybe this'll be an opportunity to mod them. I've never liked that the LED bars only come on with the low beams and not the DRLs.
 

j91z28d1

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They are aftermarket units. They plug into the factory bulb sockets and are internally wired from there. The DRL and low beam circuits must be joined because the low beams are single-filament bulbs. This weekend I'll pull everything apart and diagnose it. I'm hoping there's a short in one of the housings that's causing the issue. That'll be easier to fix. Maybe this'll be an opportunity to mod them. I've never liked that the LED bars only come on with the low beams and not the DRLs.


ahh makes sense. I have different aftermarket ones.. they kinda do the same thing but are led so they don't pull much power and no drl. it uses a external wire to a fuse tap for the led bar for the drl. it just dims when the head lights come on. but it's on a fuse that has power anytime the key is on. not sure if you could wire it like that some how.

if you happen to still have your stock housings laying around to troubleshoot with that could be helpful. I tossed mine back the box and thought I'd polish them up and sell them because they didn't look you bad but never got around to it haha.
 

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