Headlights go dim randomly

[JaTech]

So that's about it randomly while driving (or with the engine off and the lights on) the headlights will just go dim. I haven't noticed the high beams doing it and it wouldn't be that big of a deal but it's so low it's very noticeable I go from great visibility to not being able to see someone stand 2 feet in front of the vehicle.

Any advice or previous experience with this?

[SnomanAndASwede]

There's a sensor that performs a test and if its driven too soon after startup your voltmeter will drop when the headlights dim for a second. Dealer provided me with a TSB on this and I let it run for a minimum of 20-27secs when starting up(there's a noticeable tick/click when this happens) voltmeter may jump too. Scary yes, check the charging system. I hated it and thought it mat appear as if i was flashing my lights. Run it for 30seconds every startup. hasnt happened again in years. Occasionally I notice the voltmeter drop and jump back just as quick. headlights dimming after shutdown is the battery. No other way to keep em on otherwise

[JaTech]

Initially it was only while starting the vehicle but lately it occurs over and over the entire 45 minute ride home to and from work every day.

and what I meant is it will be dim then go bright and back and forth with and without the engine running even seconds after shutting off the engine.

[SnomanAndASwede]

When they go dim is there a loss of power? Do the interior lights dim as well? Is the charging system gauge holding steady the whole time they go dim and back to normal?

[JaTech]

Originally Posted by SnomanAndASwede

When they go dim is there a loss of power? Do the interior lights dim as well? Is the charging system gauge holding steady the whole time they go dim and back to normal?

Thanks for the help, it seems like a loss of power yes but no other power systems in the TB go dim (head lamps, gauge leds, etc.) the charge gauge is indeed holding steady the entire time (just verified). I've had the brights on plenty without that issue but the low beams it happens every time (both sides btw)

[freddyboy61]

I would try unseating and then reseating relay #45 in the underhood fuse panel. If that doesn't help swap relays 45 & 46 to test if its the relay.

[JaTech]

They were different for mine (the #'s) reseated, switched around and it stays ok then about 5 mins into turning it on it does the same thing, also note I've secured all connections I could find, disconnected the - terminal for 5 mins and reconnected, and reset the computer (by overturning the key for 30 secs).

Still goes dim randomly

[GM Customer Svc]

Originally Posted by JaTech

So that's about it randomly while driving (or with the engine off and the lights on) the headlights will just go dim. I haven't noticed the high beams doing it and it wouldn't be that big of a deal but it's so low it's very noticeable I go from great visibility to not being able to see someone stand 2 feet in front of the vehicle.

Any advice or previous experience with this?

JaTech,

I am sorry you are experiencing this issue with your vehicle. I have researched your vehicle and there are currently no known issues as you have described. I recommend consulting with a certified technician, as I suspect an electrical issue. The technician will be able to offer more information after inspecting the vehicle.

If you need assistance locating a technician near you, please PM me your zip code for a listing.

Louis (assisting Evan)
GM Customer Service