Turn on headlights, dash lights go off. Please help!! - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > OEM Issues

OEM Issues Original Equipment Repairs and/or Problems

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  #1  
Old 03-12-2009, 05:36 PM
Rhizzlebop Rhizzlebop is offline
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2004 Chevy TrailBlazer LT
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Turn on headlights, dash lights go off. Please help!!

I have an 04' LT w/ 83K. I replaced the battery about 20months ago due to local tire shop finishing it off while doing the alignment. (Another story). I replaced with the "best" Exide they had 84m/3yr100%.

It has run flawlessly till yesterday. Without warning, I drive to lunch, get in to come back, dead. It just clicks a few times. I get a jump, fires in about 20 seconds.

It runs fine about 30 minutes until I got to a repair place. (During that drive, the only thing that seemed of note, was during acceleration the charge hand was a micro fraction to the good side of 14v, and during idle or coasting, it was a little more to the lesser side of 14V. Upon reaching the place, turned it off, hit the key, dead again.

The place tests it out after charging the battery for 2 hours, and they say the battery is dead (100% covered), and that the alternator is bad and killed the battery. They wanted 430 dollars to replace the alternator with a remanuf with a 3yr warr.

After a couple calls, and suggestions, I had em replace the battery and I took it to Autozone and had em check the Alt. He checked it with two clips on the battery, had me rev the engine, and it was showing 14.09v regardless of RPM between idle and 2400.

I left there, everything seemed fine. Sun was up.

This morning, I crank the car in my garage, headlights pop on, but no dash illumination and tha radio is dark. (even the clock).
I drive to work at 8AM, no dash lights. At lunch today, I get in, hit the key, everything turns on as normal with the radio showing and all.

I immediately connected that the lights were off due to the sun being up. I reach over and turn on the lights manually and as soon as I click it the first notch to running lights, all the dash lights and clock go dead. But, the actual radio still plays.

Weird. I have no idea what link could cause one to affect the other and what any of that could have to do with replacing the battery yesterday.

Any ideas? I would much appreciate the information.
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  #2  
Old 03-12-2009, 05:43 PM
Rhizzlebop Rhizzlebop is offline
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2004 Chevy TrailBlazer LT
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As a side note, from what I'm hearing, people think pretty low of Exide batteries. I was more or less without options as I was stranded at the tire store 20 months ago with a dead battery and needed a new one.

The chevy mechanic I called suggested I just replace the battery and "see what happens", which is what I did.

He said, batteries now die without warning, more like a light bulb, and in his opinion, I wouldn't need an alternator at 83K, especially if (per the other mechanic who had the car at that time) it was putting out 16v.

(The place that wanted to replace the alt. told me that it was reading 16V, and then dropped to 10V.

When I had it autozone, I was watching the machine myself, and it was rock solid on 14.09V regardless. Of course that was after the new battery was put in.

In summary, I thought all was fixed with the new battery, but now their weird thing is going on with my dash lights.

I read on a different forum where someone said a battery change can sometumes confuse the computer and various sensors, and unhooking the battery for 35 minutes and reconnecting could straighten that out.

Maybe its confused and the sensor/relay is seeing headlamps on, turn dash off, headlamps off,dash on. Perfectly opposite, in sync.
??
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  #3  
Old 03-12-2009, 05:52 PM
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rbarrios rbarrios is offline
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on these cars- the computer can control the alternators output...
so its not like the old days when the more you revved- the more Voltage you saw.
lets see what others say....
sounds like the parts store just hooked up a meter to it to read the voltage at the battery.

If you have a scanner or software for the OBD port... these can read and display the voltage the computer sees .
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  #4  
Old 03-12-2009, 05:54 PM
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tblazed tblazed is offline
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Quote:
Originally Posted by Rhizzlebop View Post

This morning, I crank the car in my garage, headlights pop on, but no dash illumination and tha radio is dark. (even the clock).
I drive to work at 8AM, no dash lights. At lunch today, I get in, hit the key, everything turns on as normal with the radio showing and all.

I immediately connected that the lights were off due to the sun being up. I reach over and turn on the lights manually and as soon as I click it the first notch to running lights, all the dash lights and clock go dead. But, the actual radio still plays.

Weird. I have no idea what link could cause one to affect the other and what any of that could have to do with replacing the battery yesterday.

Any ideas? I would much appreciate the information.



Maybe the instrument panel lighting illumination control is turned all th way down?
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  #5  
Old 03-12-2009, 05:58 PM
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the roadie the roadie is offline
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Your 14.09V sounds just right. One high failure rate item that's the cause of many, many mysterious ignition and starting problems is the ignition switch itself. A very cheap and easy repair - just run a search and you'll find threads about how to do it with pictures. Not necessary to take the key cylinder or anything out - it's just an electrical part on the bottom of the steering column.

Pulling the battery for 30 minutes is indeed a way to reset the computers in the vehicle, but there really isn't any relationship from headlights to dash lights except if the body control module is confused.

See if you can swap out the ignition switch to eliminate that worry. And try the battery reset. I'll continue to think about what could interact in the lighting circuits.

Quote:
Originally Posted by tblazed View Post
Maybe the instrument panel lighting illumination control is turned all th way down?
Ahhhhh, that's the ticket. A total coincidence with changing the battery, but it would explain the dash light issue.
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  #6  
Old 03-12-2009, 06:06 PM
Rhizzlebop Rhizzlebop is offline
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to, barrios, It is correct that the parts store read the voltage with a large rolling meter. They put a clamp on each batter terminal, and saw that it was outputting 14.09V regardless of RPM. Which he and I both deemed as good.

To, tblaze, I don't know what that control is or where I'd change it, but its not been changed. the illiumination of the radio clockw as fine in the sun yesterday when I picked up the car. It and the entire dash was dark in my garage this morning when it was semi dark, and the headlights were on, and the clock and dash were back on this afternoon at lunchtime when the sun was up, and thelights were off. As soon as I manually turned on the lights, the clock went black and dash lights were out.

I actually thought the radio was completely without power until I turned up the volume and realized it was powered and playing, but completely dark, no display of any kind.

t roadie, I'll try the battery reset. As far as ign. switch. I've never messed with any of that. Kind of scared to, but I'll search for the how to thread with pics. Where should I get the part? I have ZERO faith in any part sold by the autopart places, Autozone, etc... I'll have nothing from them but wiper blades. lol
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  #7  
Old 03-12-2009, 06:21 PM
the roadie's Avatar
the roadie the roadie is offline
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The instrument panel intensity control is to the right of the headlight switch. It's a rotating knob that can also be pushed in so nobody touches it. If it's flat against the switch housing, push it in and it will pop out. Turn clockwise. Read the Owner's Manual as well - it's full of great stuff.

Yes, the aftermarket parts places should have this switch. You pay more at the dealer and in this case the part is nothing special. In many cases the aftermarket parts FIX the problem with the original GM design.
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  #8  
Old 03-12-2009, 08:52 PM
Rhizzlebop Rhizzlebop is offline
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Ok, I feel like an idiot!!

It was the brightness turned down. What seemed weird, and still seems weird, is why would the clock/radio area be unaffected by that knob UNTIL the lights are turned on?? And why would they let you turn it down until the dash is totally dark?

That results in weirdness when you see the clock/radio all lit up, and as soon as you turn on the lights, it all goes dark.

I guess when the guy put in the battery, he messed with that knob and turned it all the way down.

I've browsed this site a couple months now, and was waiting to post on something valid, and now I wasted my first post on something silly, lol

I still could have a prob with that alternator, but the charge hand sure is rock solid and steady with that new battery.

I think if this battery fails in another year, I'm gonna say to heck with the battery warranty, and go buy the biggest Interstate that will fit in the well.

Thank you all
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  #9  
Old 03-12-2009, 09:42 PM
the roadie's Avatar
the roadie the roadie is offline
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Quote:
Originally Posted by Rhizzlebop View Post
What seemed weird, and still seems weird, is why would the clock/radio area be unaffected by that knob UNTIL the lights are turned on??
In the daylight mode, they assume you want the brightness full up, I guess. This is not the weirdest engineering decision in these vehicles. Not by a long shot.
Quote:
And why would they let you turn it down until the dash is totally dark?
Some folks can't stand to drive with any interior distractions, I guess.
Quote:
I guess when the guy put in the battery, he messed with that knob and turned it all the way down.
That's the ticket. Most guys blame their wives or friends who borrow the car. You got the right idea.
Quote:
I've browsed this site a couple months now, and was waiting to post on something valid, and now I wasted my first post on something silly, lol
Glad we could help you while you were lurking. And your post wasn't a total waste if we get to educate ourselves and pass it on to others. You would not BELIEVE what we regulars see for first posts. How do I get the spare tire down? You mean there's a rear fuse block?!? My buddy/wife just jump started the car and now none of the dashboard lights work! What's the biggest tires I can put on without cutting the fenders? All things that have been discussed dozens of times or are mentioned in the Owner's Manual.

Now have you ever cleaned your throttle body and exercised your 4WD system?

Now I just have to defend myself against tblazed's future gloats about nailing this fix before the rest of us. Nothing worse than being on the butt end of a good gloat.

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  #10  
Old 03-12-2009, 10:31 PM
Rhizzlebop Rhizzlebop is offline
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2004 Chevy TrailBlazer LT
Majestic Red Metallic 4.2L I6 2WD
Join Date: Jan 2009
Location: Columbia, sc
Posts: 37
roadie, thanks a ton

I understand wanting the dash lights bright when there is sun. Iunderstand wanting to dim them sone. Wanting them completely off, (aka, allowing to dim to off), makes no sense.

Funny funny about the blame thing. I t had to be him, cause I didnt even know those dash lights would dim, and I've had the car since it was new. I only ever used that knob to turn on the interior lights, and noone else drives my car ever. My radio was on some rap station when I got back in too, and I don't listen to that. lol

Only body I've cleaned is myself, and don't have 4wd.

Cant help much on the gloating but he did nail it. Just hope the alternator is good.

As far as the questions you see, I promise, I do believe it. I am a consulting engineer in HVAC design, and I post on HVAC talk, helping others in an area I know a lot about and the dumb questions abound!! lol

take care. After I pull a trailer full of dirt tomorrow (about 6500lb) I might be backing, why did my transmission fall out.
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