Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

1 - 7 of 7 Posts

·
Registered
2004 chevy trailblazer_lt
Joined
·
13 Posts
Discussion Starter #1 (Edited)
Have a different problem I have never run in to before.... My headlights randomly come on while the Trailblazer is parked! Here is the background so far:

Came out of work last Tuesday evening to find a dead battery. Jumped it, and put it on the charger when I got home. The headlights were off.

Went out with my wife in her car, leaving the charger on automatic for an hour. When we got home, the lights on the TB were ON. Flicked a couple of the switches and they went off. Let the battery recharge again without the light coming on, and disconnected the battery for the night.

Drove the TB to work the next morning, and parked it facing my office window where I could see it. Lights went off after the standard delay when the car was shut off. 45 minutes later, I noticed the lights were ON! Flicked the high beam switch on the steering column once to engage them, and the lights shut off.

Did not have the issue again until Saturday evening. Drove the TB once during the day, and noticed in the evening the lights were ON. Flicked the dash-mounted switch, and the lights went off. Drove into work this morning, and it was a repeat of last Wednesday – the lights came ON while I was in the office, and a quick flash of the lights resets the “system”.

Other notes: I just passed 200,000 miles a week ago, but I didn't celebrate so maybe it is just being cranky.....

Any insight as to where to look at the fuse/electrical system would be greatly appreciated! I’m suspecting one of the relays, and am ready to replace them all. I don’t know if it is associated with the daytime running light circuit since it only occurs after I’ve driven it, or if it is the low beams.
 

·
Registered
2004 chevy trailblazer_lt
Joined
·
13 Posts
Discussion Starter #2 (Edited)
Update

I'll reply to my own question to give everyon an update on the probable resolution.

Caught the opportunity a couple of nights back to have the lights on while at home in the evening. Pulled each of the low beam fuses, and that caused each light to go out individually. Check.

Pulled relay #45. Nothing happened. Check.
Pulled relay #46. Lights went out. Check.
Plugged #46 back in. Lights back on. Check.
Repeat pull/plug on #46 with same result. Check.
Pull #45 and plug into #46... Lights out. okay...
Plug old relay #46 back into socket... Lights out!

It appears that relay #46 was working in cahoots with some other circuit in the system to tigger the problem. It took plugging relay #45 into #46 socket to reset the condition. Odd failure mode for the relay as far as I'm concerned.

I've replaced relay #46 and haven't had an issue again so far....:woohoo:
 

·
Registered
Joined
·
7 Posts
Update

I'll reply to my own question to give everyon an update on the probable resolution.

Caught the opportunity a couple of nights back to have the lights on while at home in the evening. Pulled each of the low beam fuses, and that caused each light to go out individually. Check.

Pulled relay #45. Nothing happened. Check.
Pulled relay #46. Lights went out. Check.
Plugged #46 back in. Lights back on. Check.
Repeat pull/plug on #46 with same result. Check.
Pull #45 and plug into #46... Lights out. okay...
Plug old relay #46 back into socket... Lights out!

It appears that relay #46 was working in cahoots with some other circuit in the system to tigger the problem. It took plugging relay #45 into #46 socket to reset the condition. Odd failure mode for the relay as far as I'm concerned.

I've replaced relay #46 and haven't had an issue again so far....:woohoo:
I have the same problem and replaced the expensive switch despite the service manager telling me it wasn't it, because I was told to start there and it wasn't a FUSE or RELAY! . The lights stayed off all night and I was happy. The next day, they went on while I was in a store getting some groceries. UGH! So now.. I disconnect the battery when I turn off the engine anywhere I am! Today I'm going to replace #46.After spending 3 days at the auto repair and having that darn switch replaced, I am changing #46 today!!! We could have told them to do that a week ago, but noooooo, I'm a woman and don't know anything about cars. I've only been driving them for 57 years! :) Thanks for this post.When will they learn that women know more than cleaning the house and feeding them? The car has 199K miles. Almost everything has been replaced under the hood. It runs great except for this.
 

·
Registered
Joined
·
7 Posts
Update

I'll reply to my own question to give everyon an update on the probable resolution.

Caught the opportunity a couple of nights back to have the lights on while at home in the evening. Pulled each of the low beam fuses, and that caused each light to go out individually. Check.

Pulled relay #45. Nothing happened. Check.
Pulled relay #46. Lights went out. Check.
Plugged #46 back in. Lights back on. Check.
Repeat pull/plug on #46 with same result. Check.
Pull #45 and plug into #46... Lights out. okay...
Plug old relay #46 back into socket... Lights out!

It appears that relay #46 was working in cahoots with some other circuit in the system to tigger the problem. It took plugging relay #45 into #46 socket to reset the condition. Odd failure mode for the relay as far as I'm concerned.

I've replaced relay #46 and haven't had an issue again so far....:woohoo:
 

·
Registered
Joined
·
7 Posts
Thank you, thank you so much! I replaced the 46 relay and no problems. praying it works for the life of the relay!
 

·
Registered
2002 chevy trailblazer_ltz
Joined
·
34 Posts
Just a notice to y'all with this problem.

The relay #46 can take care of this sometimes but if you find yourself with that Relay not curing the issue unfortunately the problem lies in the BCM.

You will have to get one and then it programmed with a tech 2 tool. They can even be a pain in the ass to program to the updated new vehicle.
 

·
Registered
2006 chevy trailblazer_lt
Joined
·
76 Posts
I had an issue with the #46 relay going bad too. On my '06 Trailblazer, I lost my low beams when I left the house at dusk one night. I wasn't too far from the house when I noticed no headlights and made a u-turn back to the house. After about ten minutes of research online and directly looking at the in-engine bay fuse block, I swapped the #45 and #46 relay. Presto, the low beams came on instantly! So, in the morning, I drove to a parts store and got a new relay.
 
1 - 7 of 7 Posts
Top