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Chevy TrailBlazer Headlight Questions

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  • lvenemalvenema Posts: 2
    My 2005 Trailblazer has had an intermittent problem with the headlights dimming since it was new. It usually only happens shortly after the engine has started after sitting quite a while. It happens after the vehicle has been driven for a few miles, the lights are on auto, and the heater/AC is on max blower speed.

    The last time it happened was during a snow srtorm. I had just about everything electrical turned on and it dimmed the lights off and on for about 30 minutes. It seems like the electrical system can't put out enough power.

    The dealer has applied fixes in all applicable TSBs with no fix. GM Tech support says this is normal? Somehow I just can't see that it is normal to have lights dimming while you are driving down a dark highway.

    Anyone else have problems like this that have been fixed?

    Thanks,

    Lou
  • lisa31071lisa31071 Posts: 1
    Thank you so much.. These instructions were perfect. It only took us about 10 minutes. Without out your help I would have never figured it out. :)
  • tuskertusker Posts: 1
    I replaced the driver side low beam. All I had to do was remove the battery cover and battery and I was able to pull the round rubber cover off and twist the light bulb assembly right out. Just be careful when you replace the bulb. Make sure you DON'T TOUCH THE BULB WITH YOUR BARE HANDS! This could cause the bulb to explode!
  • pdesimonepdesimone Posts: 6
    I have a 2003 Chevy Trailblazer. Just recently, both of my headlights went out. Whether I have it in the automatic position or if I put them in the "manual on" position, they don't come on. When I put on my brights, they work. At least they got me home. I'm sure I pissed some people off though. Anyway, does anyone have any ideas of where to look. I checked the fuses. There is a different fuse for each headlight and they both look OK. Could it be the bright switch, and if so, how do I check it? Looking forward to any help you can shed on the subject.
    Thanks
    Phil
  • pdesimonepdesimone Posts: 6
    Sorry if this went out twice but, I'm not sure what I did.
    Anyway
    I have a 2003 Chevy Trailblazer. Just recently, both of my headlights went out. Whether I have it in the automatic position or if I put them in the "manual on" position, they don't come on. When I put on my brights, they work. At least they got me home. I'm sure I pissed some people off though. Anyway, does anyone have any ideas of where to look. I checked the fuses. There is a different fuse for each headlight and they both look OK. Could it be the bright switch, and if so, how do I check it? Looking forward to any help you can shed on the subject.
    Thanks
    Phil
  • tblazedtblazed Posts: 945
    Low beams are driven by a module in the underhood fuse block. #46 is the Headlight Driver Module ("HDM") which is a solid-state relay. This is becoming a common failure. You can test it by temporarily swapping it with #45 the "Cooling Fan" driver module for the fan clutch as they are the same type device. If that's it you will likely have to buy the replacement from a GM dealer. Prices can vary from about $25 to over $40 for that module depending where you buy it. Good Luck!
  • pdesimonepdesimone Posts: 6
    I swapped #45 with #46 like suggested, but my headlights still don't come on. What are the chances of both modules going bad? #45 is the "Cooling Fan" driver module. When I swapped them, the main fan still went around. I don't know if it controls the speed of the fan or the fan all together.
    What are the chances of both of my low beams going out at the same time? Is there a highbeam/lowbeam switch on the column and could that be bad? How would I check this? Can I check the low beam with a test light. I'm trying to check everything before I have to go to a Chevy Dealer.
  • tblazedtblazed Posts: 945
    The fan will still turn. The driver module for the fan controls the amount the fan clutch is engaged and the fan speed. There is a minimum amount of drag in the clutch so even at minimum it will still turn, just not very fast.

    The headlight driver module (HDM) is controlled by the Body Control Module (BCM) under the back seat via a pink-white stripe wire that connects to the HDM pin 5 under the hood. The headlight switch signals the BCM to turn on the headlights. There are a few tests you could do to narrow it down to the BCM but that would involve shorting the pink-white stripe wire at the BCM or pin 5 at the HDM to ground, which will make the HDM turn on the headlights. DO THIS AT YOUR OWN RISK! You should be able to pull up the HDM slightly to get under it to pin 5, then with a suitable clip lead to ground and probe like a piece if solid wire, touch the pin. Be aware that there is direct Battery 12V on pin 2 so don't accidentally short that pin to ground or sparks will fly! You could also test both headlamps by taking them out and checking with an Ohm meter. Should read near zero Ohms. Pretty unlikely though that both would fail at the same time. Likewise with the two fuses.

    Since yours is a 2003 it shouldn't have a HDM fuse #53. I believe that fuse was added in late 2004 but you might check for that anyway to make sure.
  • pdesimonepdesimone Posts: 6
    Thanks for the info.
    Before I dove into the BCM, I decided to check for juice at the bulbs themselves. I seemed very unlikely that they would both blow at once, that's why I didn't check it right off the bat, but that's what it was. On the 2003, it looks like it's hard to get to the bulbs, but it was easier then I thought. The passenger side, I had to take off the cover for the air filter and I could reach my hand in. In any case, two lights and only $16. later, it was all fixed. Now, why did they both go at once. I had noticed a slight dimming a couple of times in the near past and I read somewhere that the Trailblazer had some alternator spiking problems. I guess I'll have to keep my eye on it.
    Thanks for your help.
  • pdesimonepdesimone Posts: 6
    I own a 2003 Trailblazer and I just had to replace 2 low beams. I don't know if things have changed from 2002 to 2003, but on the 2003 it looks harder than it really is.
    On the driver's side, reach down and in and pull off the black rubber cover that's about the size of the bottom of a soda can. Then just reach in and twist and pull. On the passenger's side, you first have to take the 3 screws out of the air filter cover and pull it off. Then, reach down and in and twist and pull. It was. Remember, don't touch the halogen bulbs with your fingers, the oil on your fingers screws them up for some reason. At least that's what they used to say. Hope this helps.
    Phil
  • :shades: Thank you so much for this post!!! It actually took me less time then is listed it was only about 10 minutes total time to take it apart replace them and put it back together...These directions are awesome...There is only one thing I would like to add...When you do this make sure the front end of the truck in the grass or place a blanket down in front of the truck...When I popped off the last clip the grill fell on the ground and scratched the paint a little no big deal, just a little hint though...Thanks again!!!
  • tayag08tayag08 Posts: 1
    I have had two different mechanics check the headlights out on my car, and I've yet to have any luck getting them fixed. The bright lights always work, but the dims sometimes go out. Sometimes I can turn the car off, turn it back on and they work. Other times, they don't work for a while, and even sometimes, I think they're going to work and they go out while I'm driving. Has anyone experienced this problem or know how to fix it?
  • svmilamsvmilam Posts: 1
    I have a 2003 same problem trying to find the solution
  • I have a 2004 Chevy TrailBlazer. I got hit by something overnight and it resulted in a shattered left tail light. I have purchased a replacement, but have no idea how to switch them out. Help.
  • I will have to go with the posting by Phil on this one. No grill removal or anything complicated. Just removing the air filter and the rubber covering and that is it.

    Refering to Phil's message:

    I own a 2003 Trailblazer and I just had to replace 2 low beams. I don't know if things have changed from 2002 to 2003, but on the 2003 it looks harder than it really is.
    On the driver's side, reach down and in and pull off the black rubber cover that's about the size of the bottom of a soda can. Then just reach in and twist and pull. On the passenger's side, you first have to take the 3 screws out of the air filter cover and pull it off. Then, reach down and in and twist and pull. It was. Remember, don't touch the halogen bulbs with your fingers, the oil on your fingers screws them up for some reason. At least that's what they used to say. Hope this helps

    Yes even a blonde can do that.

    Diana
  • shoes2shoes2 Posts: 2
    Lou
    I have a similar problem. Occasionally while driving down a road and lifting off the accelerator the headlights begin to flicker almost like going from a high bean to a low beam. I haven't noticed it happening with any special accessories on or off. Since its dark in the mornings when I drive to work now I notice it more often. I haven't bothered taking it to the dealer since I think it would be a waste of time. I'm actually not even sure if it both headlights or just one, but whats happening is noticeable and probably puzzles the oncoming drivers.

    Dick
  • I just took mine to the dealer to have this checked out. They told me that everything checks out okay and that GM has a paragraph (somewhere) that says that this is normal when the car is under heavy electrical load. I don't exactly buy this as I have had mine dim when there is very little load being put on the system. Even with a load the system should be able handle it in my opinion or there is a problem. If this truly is "normal" then GM has a bad design for their electrical system. I have talked to others with TB's and haven't had anyone else tell me that they have this problem, so my question is - if this is "normal", why is it not seen in all vehicles? :mad:
  • It's cold outside but I had to change my passenger side low beam head lamp.
    Stump3, thanks for the info. I was done in 6 minutes. I didn't have to remove the grill or the housing and it was done in a snap. Is there a trailblazer club I can join?
  • I have had my 04 TBLS for 6,000 miles since October of 07 now i am the second owner it is a GM certified vehicle, if that means anything more than when it gets me mad ill seiz the motor and let them have it back lol. My headlights have been doing the dimming game since i got it. I just think of it as my strobe system, it only does it when its in a bad mood i guess. Everything else works fine. I have seen all over the net, where not the only ones. GM may make a recall someday but for now ill just use my brake pedal as a way to dim my lights to make deer run away. HEY ITS A CHEVY NOT A NASA SPACE SHIP! Either way there made in the USA! At least we don't have to worry about them falling out of the sky! I love my Trailblazer for that reason and many more.
  • gzupangzupan Posts: 1
    Thanks so much for the simple instructions. I had no problem following them. And yes, the driver's side is much easier than the passenger side. I Actually had to do it twice....my passenger's side was out and I replaced the driver's side.....duh! Thanks again.
  • I had a very similar problem with my 05 TB. After two days of troubleshooting and replacing the alternator, confirming grounds, etc. GM tells me I needed a new battery. I'm picking it up tonight and I guess we'll see if it's "really" fixed.
    A person doesn't need the added attention of lights strobing.
  • My right front headlamp kept blowing the lowbeam bulb. When I removed the lamp to replace the bulb I found the bulb socket brown and slightly melted. I wired in a new socket with one from Carquest and have not had any more problems. It looked to me like the original socket was of poor quality.
  • My TB acted up within days of delivery. First dealer reprogrammed the computer for a problem with the lights dimming while at idle. No fix. Second dealer replaced a couple of electronic modules, repaired some grounds and make more checks. Called tech support, was told the problem was the emission system, AIR pump or something like that, was the problem. It could come on at any time and was a heavy load on the electrical system. It happened one morning when coming home from work in a bad snow storm in the country. The lights were constantly blinking, both inside and out. Finally got tired of the terrible mileage and the untrustworthy electrical system and got rid of it before it went out of warranty.
  • I don't know why I haven't searched for fellow 05 TB owners with strobe lights for head lights. My head lights started dimming from high/low to off about 3 years ago, with the conditions right, like: foot off the accelerator, no one if the passenger seat (air bag would be off then). Slowly, the interior lights began to dim as well. I took it in; of course, nothing found. They just tightened the battery cables.

    A month later, the lights began to dim again. Only this time, there was associated powering down of the engine...at least that's the easiest way to describe it. That has continued after another trip to the shop and a complete diagnostic work-up. It has continued, now seems to do it occasionally with day time lights and at night regardless if I have a passenger or not. The only thing that remains the same as the start is no dimming when accelerating or constant speed using the accelerator. Lights dim with cruise, braking, or just coasting.

    Warming up the car doesn't help. It can start 5 minutes after turning it on or 30 mins. Just this morning, it was the worst ever! Felt as though the car was going to stall completely. A 20 min drive. Dimming all around for the whole drive. Went to the dealer, picked up the head service guy. No, he didn't get to experience it b/c it stopped when I hit city limits. Oh, and now change in any gauges. Voltage and RPM's remain the same. No difference with increase/decrease in electrical use inside the cabin.

    Anyone else experiencing the combined lights and engine 'dimming'???

    Thanks!
  • 2003tb2003tb Posts: 1
    jseto - your directions are right on except my TB doesn't have a fender brace on the PAX side. Thanks for posting.
  • I have a 2005 Trailblazer and the passenger side highbeam headlight will not turn off. It's on even when the car is off. Any ideas?

    Thanks
  • con57con57 Posts: 1
    My front head light is out, there is no information in the owners manual as to remove and replace it. any information on how to do this would be great.
  • mcarlinmcarlin Posts: 1
    I started researching these problems because I have a 2005 TrailBlazer that has had this same problem since I purchased it. Driving at night it is more noticable than in the day time, however it happens all times of night and day. The interior and exterior lights will dim, the A/C fan will slow down, and at times the engine will loose power. I have had it in to the dealer every couple of months and they can't find anything wrong with it. They changed the battery last week, but it did not help. I was told that until it throws an error into the computer they cannot trace it. I was also told that one other GM vehicle has had a similar problem and a recall, the wiring harness was found to be defective. However it was not the TrailBlazer. With all of these similar problems, there has to be a common thread.
  • gfriesgfries Posts: 1
    I have an 02 trailblazer with a viper alarm system. Recentely the alarm has been going off two times, consecutively, once we arm it. Noticed that the front head lights are staying on for 7.5 minutes after we activate the alarm before it goes off the first time. Then we reset it, the parking light stays on for 2.5 minutes and it goes off again. We reset this time and all is ok. Does anyone have any knowledge of a timer system or anything else on the headlights that may be causing this to happen?
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