Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

1 - 17 of 17 Posts

·
Registered
2005 chevy trailblazer_ls
Joined
·
15 Posts
Discussion Starter #1
Hello fellow Trailvoy members,

I have an '05 Trailblazer with 80,000 miles, and recently the headlights have started to randomly turn themselves off. I run with my daytime running lights (DRL) all the time and hardly ever even touch the light switch since the dash lights come on automatically (thanks Chevy). And of course I only notice when it happens at night since I can't really see if the lights are on or off during the day, and it is quite scary at night...especially when it happened recently on a dark country road in Mississippi. :ugh:

Anyway, when it happens I try to fiddle with the switch when it happens, and it never comes back right away, and the last time they almost seemed to come back by themselves . I even tried stopping and shutting off the vehicle and re-starting, but that did not help.

I am just wondering if anyone else is having or has had this problem, and what might the problem be? Faulty switch, faulty relay, etc. And yes, both my headlights work and they are both cutting out. Brights work well too...rather too well (thanks again Chevy).

:thx

Ryan
 

·
Registered
2004 chevy trailblazer_lt
Joined
·
1,298 Posts
So it's only happening with your low beams?

Swap underhood relays 45 and 46, see if the problem continues. The most
common problem that takes out both lows seems to be the relay, or
at least a poor connection in the relay socket.

Check the wiring as well. While it's less likely to lose and regain both lights
at the same time with a wiring problem, it's at least possible.

My bet is on the relay.

If the relay swap doesn't change anything, how handy are you with a
multimeter?

Good Luck-

Chris
 

·
Registered
2005 chevy trailblazer_ls
Joined
·
15 Posts
Discussion Starter #3
Cool. I will try those swaps. Am I handy with a multi-meter? Well, I do build guitar tube amps, but you had no way of knowing that. :) Is there something I can check.
 

·
Registered
2004 chevy trailblazer_lt
Joined
·
1,298 Posts
Heh....guess you would have to know your way around a meter if you're
working with tubes. High voltage, too! :) Love the sound of tube amps... :)

If the relay didn't fix things, then you'd have to start looking at the power
feed to the relay as well as the ground path. If the relay wasn't getting the
signal to trigger properly, like from corrosion in the socket or a bad ground
not completing the circuit path, then the lights would go off until the relay
was triggered again. They're solid state relays, too, so it's not quite as
easy as a regular coil and contact type.

Cheers-

Chris
 

·
Banned
2003 gmc envoy_slt
Joined
·
7,190 Posts
:iagree:

There have also been reports of loose contacts in the fuse box, but my bet would be the relay.
 

·
Registered
2005 chevy trailblazer_ls
Joined
·
15 Posts
Discussion Starter #6
I swapped relays 45 and 46 so I guess I can see if it in fact the relays or the contacts. I have never had any issues with the cooling fan, so that relay should be good. It may just be that zener diode going out on the headlight relay. I'll drive around awhile and I'll report back in awhile and see what happens to see if my headlights still go out or my cooling fan starts going in and out or both.

Thanks very much for the help guys! :tiphat
 

·
Banned
2003 gmc envoy_slt
Joined
·
7,190 Posts
I swapped relays 45 and 46 so I guess I can see if it in fact the relays or the contacts. I have never had any issues with the cooling fan, so that relay should be good. It may just be that zener diode going out on the headlight relay. I'll drive around awhile and I'll report back in awhile and see what happens to see if my headlights still go out or my cooling fan starts going in and out or both.

Thanks very much for the help guys! :tiphat
Keep a close eye on the engine temp.

If the relay is bad, the fan won't go in and out. It just won't cool the engine.
 

·
Registered
2003 gmc envoy_sle
Joined
·
20 Posts
Hello fellow Trailvoy members,

I have an '05 Trailblazer with 80,000 miles, and recently the headlights have started to randomly turn themselves off. I run with my daytime running lights (DRL) all the time and hardly ever even touch the light switch since the dash lights come on automatically (thanks Chevy). And of course I only notice when it happens at night since I can't really see if the lights are on or off during the day, and it is quite scary at night...especially when it happened recently on a dark country road in Mississippi. :ugh:

Anyway, when it happens I try to fiddle with the switch when it happens, and it never comes back right away, and the last time they almost seemed to come back by themselves . I even tried stopping and shutting off the vehicle and re-starting, but that did not help.

I am just wondering if anyone else is having or has had this problem, and what might the problem be? Faulty switch, faulty relay, etc. And yes, both my headlights work and they are both cutting out. Brights work well too...rather too well (thanks again Chevy).

:thx

Ryan
rtaylor76's (Ryan)

Hey Ryan I am having the same issue (the EXACT same issue.) At first I thought it only happened in the rain for weeks but last night 12.09.12 it happened when I was almost home but luckily I have the fog lights to see or high beams. Yeah my fogs work fine. THEY STAYED OFF FOR 10 MINS AT LEAST then magically came on.

Have you figured anything out yet..MUCH APPRECIATED :thx

Justin, NJ
Can you tell me
 

·
Registered
2006 chevy trailblazer_ss_ls
Joined
·
2,251 Posts
I am a GM technician. The body computer module needs to have the codes read. The codes will you what parts to replace. I'm thinking bcm, headlight switch, and wire harness to start.
Spoken like a true GM tech...

They train you to say that? "To start?" :weird:
 

·
Registered
2005 chevy trailblazer_ls
Joined
·
15 Posts
Discussion Starter #10
First off,

tony267 - it is not throwing codes. Just headlights turning off.

And whoever deleted his message, I thank you.


03 Envoy JRL - I only have driven at night a couple of times so far, and once was not for very long. I did notice the two times it did happen it was after a long trip. For now the lights have not turned off since I swapped relays, and my fan seems to be working fine. So I am thinking it is the relay, or a connection to the relay. For now everything is working, but a replacement relay is only $30 or so from Rock Auto if I need. I know it is annoying and not good, but I am kinda glad I am not the only one experiencing this problem. Have you swapped yours yet?

I wish I could tell if my headlights were working in the daytime though. I am not sure how I would do it unless I affixed a white board in just in front of my lights so I could see the headlights reflection while I am driving. :undecided
 

·
Registered
2004 chevy trailblazer_ls
Joined
·
142 Posts
There are 2 black short matching relays in the fuse box sitting side by side under the hood. swap them, I had this problem before. there are only 2 of the same ones in the fuse box so you can't really mess this up. This isn't a "fix" just a way to test. you'll need to replace the relay, although its technically not a relay, but looks just like one
 

·
Registered
Joined
·
2 Posts
My 2006 Trailblazer has had the headlights go out while driving down the road. Very scary! It's very intermittent but it seems that when it does happen, it has been raining for a while. I believe there is some kind of recall on it.
 

·
Registered
Joined
·
8 Posts
Hello fellow Trailvoy members,

I have an '05 Trailblazer with 80,000 miles, and recently the headlights have started to randomly turn themselves off. I run with my daytime running lights (DRL) all the time and hardly ever even touch the light switch since the dash lights come on automatically (thanks Chevy). And of course I only notice when it happens at night since I can't really see if the lights are on or off during the day, and it is quite scary at night...especially when it happened recently on a dark country road in Mississippi. :ugh:

Anyway, when it happens I try to fiddle with the switch when it happens, and it never comes back right away, and the last time they almost seemed to come back by themselves . I even tried stopping and shutting off the vehicle and re-starting, but that did not help.

I am just wondering if anyone else is having or has had this problem, and what might the problem be? Faulty switch, faulty relay, etc. And yes, both my headlights work and they are both cutting out. Brights work well too...rather too well (thanks again Chevy).

:thx

Ryan
Buy the relay at ORielys. Life time warranty! Changed twice!
 

·
Registered
2004 gmc envoy_sle
Joined
·
20 Posts
I have an 04 Envoy with the exact problem. I could see my lights going on and off in the car's bumper in front of me. So I gather that I can change relay 45 and 46 and if that solves the issue I just need to replace the relay. One is the fan relay? if so which one is it? Thanks.
 

·
Registered
2004 Trail Blazer LS
Joined
·
8 Posts
I had an issue with the running lights/low beams staying on when I turned the truck off. Saw on here to try the relay so went to advance and purchased a relay. The low beams then started to randomly turn off with the relay from advance. Ordered a factory AC Delco relay from amazon for less money and have not had an issue since.
 

·
Registered
2004 Trail Blazer LS
Joined
·
8 Posts
The part that I purchased from Advance was BWD. No issues so far from the AC Delco and easy to find on Amazon. Someone had already replaced the relay with a BWD Relay before I bought the truck. Hope the Ac Delco keeps lasting.
 
1 - 17 of 17 Posts
Top