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Chevy TrailBlazer Headlight Questions



  • Doing research and saw this post. I have the same issue with low beam lights going off and on....However, I have a 2007 TB - was just told by GM dealer that the "entire block" has to be replaced (part $207 and labor $160). I do not have a clue what they are talking about, except its under the seat. Does my car not have the "relays #45 and #46"? Sorry I am ignorant when it comes to cars and I am tired of getting screwed.
  • I have the same problem with my 05 Trailblazer. The lights dim because the alternator normally produces 14.5 volts. The battery output is about 12 volts. The voltage drops momentarily when the alternator fails to produce 14.5 volts. I have also noticed the problem during a hard acceleration, which caused me to think it was a slipping serpentine belt. However, the random dimming occurs while driving at a steady speed. Dealer replaced the under-hood fuse block (not the one under the rear seat) as well as the alternator. Neither action fixed the problem. I wonder if it is possible to connect the diagnostic computer and let us drive the cars for a few days with the computer connected.
  • fj4072fj4072 Posts: 29
    Your problem is your relay. #46 under the hood. If this happens again, try switching #46 with #45, same relay only for the fan clutch. If they go back on, this is your problem. Autozone has them for $40
  • I have a 2003 Trailblazer with130,000 miles. Snowed the other day and when I turned my Transfer Case Controls, nothing happened. No yellow light came on and no 4WD.
    Any ideas on what to check for. I looked in the owner's manual and saw that Fuse Number 8 says "Automatic Transfer Case" so first thing tomorrow I'll check that. That would be too easy but I'm hoping it's blown. Any other suggestions would be greatly appreciated.
  • This is a continuing dangerous problem. The night before the the night before Xmas, my wife was doing some last minute shopping before a 280 mile drive
    the next day. Wife called - no lights. She drove home with the brights while I found all this information about fuse #46 and #45, thanks to this site I switched the fuses, even though the fuse in #46 (headlamp) was then working. At least I know what to do if it happens during our trip. Merry Christmas GM, you may be bankrupt but you won't steal Christmas from us.
  • I have replaced my headlights on my 03 trailblazer at least 4 times this past year and dont know why they keep going out. a couple years ago one of the sockets melted and i replaced it and it seemed to work fine for a while bu the dam things keep going out now. Any ideas anyone would be great.
  • fj4072fj4072 Posts: 29
    First things first. Make sure there aren't any finger prints on the bulbs, the grease will cause a hot spot and cause it to blow quicker. If you do touch these bulbs, wipe down with alcohol. 2. Use die-electric grease on the socket next time, will prolong the life of the bulb and dissapate any excessive heat generated. Check for loose, or dirty connections at the battery and alternator, could have an electrical surge which will cause these to pop quicker also, cleaning these up will help. 3. Make sure you have the right wattage, I believe that OEM is 51w, but any more than 55w will blow quicker also. These are the basics, next would be replacing the wiring harness that goes to the lights.
  • question for u did u ever get the headlight problem fixed and if so what did you do. i have a 03 trailblazer and i replaced the melted socket on the drivers side and the dam thing kepps blowing again any ideas on what to do. please help this is really pissing me off
  • I did get mine fixed after going through a few bulbs and 1 socket. I eventually got 2 new sockets capable of higher temps (I think they're ceramic) from the local parts store. I guess the original stock sockets (and their original replacements) are only capable of handling the heat from the original bulbs, or their equivalent. All bulbs I tried (3 different brands) blew and/or melted the sockets until I replaced them. Since installing the high-temp sockets, I haven't had any problems.
  • burdawgburdawg Posts: 1,524
    Ditto for me. The halogen bulbs get hot.
  • where did you et the sockets i have tried all the local stores in town and no one has them. please help
  • I got my new ceramic (?) sockets from Arnold Motor Supply in Ankeny, IA. They had the stock all-plastic sockets as well, but these are clearly a different material. I haven't had a burned out bulb or socket since.
  • frnkiebfrnkieb Posts: 1
    I have an 02 chevy trailblazer with the headlamps out. high beams work, but the low beams dont seem to come on. autozone had the dashboard switch for aprox. $106 but that wasnt it. i replaced the turn signal switch ($150) that wasnt it either. all the micro switches seem to work and all the fuses were good. when the power was applied to the the correct fuses the lamps came on so i knew they were good. finally we found that there is resistor that supplies power to the lamps. apparently that was burnt out. when bypassed the lamps came on. its on order and will be replaced this afternoon. final cost $60+ tons of frustration. lol
  • Can you tell me where the resistor is, I have a trailblazer. The low beams go off and everything else works.
  • marty54marty54 Posts: 1
    I have read a lot of other post about the low beams going out and the high beams still work. I have the same trouble. I traced it to the switch on the dash and that was 120.00. Well it didn't work. I checked both low beam head lites and they were both good. I have not tried to change #45 and #46 yet that will be tomorrow night. I looked at the wiring scamatic and have seen that there is a light sensor. According to the book this sensor makes the low beam driving lights dim during the day and turns them on even higher at night because it's dark. If it's not the 45 and 46 the only other thing it can be is that sensor. That is going to be a real pain to get to because it's in the dash near the windshield. If man maid it I will figer it out it just may take some time. If any one else has had this trouble and already knows would you please let me know what it is?
  • fj4072fj4072 Posts: 29
    This is classic relay problem. I took the relay out several times trying to show it to different auto parts stores. I ended up having to special order it. In taking the relay out many times, this effectively scraped the contacts clean to bare metal. I have not had any problems with the relay since then, even after I received my new relay. New relay is in my glove box just in case, I'm going on 9 months now with the old relay after contacts were scraped clean (accidently) :) By the way, if you ever do need to get at that sensor on the top of the dash, it's VERY simple. The whole top part of the dash just pops right out, being very careful not to break that is. The plastic piece that holds it in place broke on mine, so I ended up using epoxy to fix it.
  • leilani5leilani5 Posts: 1
    Just confirming that what i read on one of the post here is correct. my lowbeams work sometimes and sometimes not. mine is 2004. according to the owners manual, fuse schematic page 5-94 and 5-96 the fuse that causes this problem is #46(Headlamp Driver Module). it is one of the xtra large black fuses. Part#15016745 is marked on the top of the fuse. the fuse directly in front of this fuse is #45 (Cooling Fan). this fuse has the same part # so i interchanged the fuses and the lowbeams came on immediately!! happy!! i found the fuse online for approx. $35 but will check with dealer in the morning as it is midnight right now. this forum has really helped me save some money. i hope i have helped someone as well. thankx.
  • fj4072fj4072 Posts: 29
    You're correct grasshopper. Note: when asking for this part, it is a relay, not a fuse. The e-bay price seems high, meaning I thought it would be 1/2 price or so. New one from Autozone is $39 part # 20601. Don't trust what part # that pops up on their website, it's not the right part. Try cleaning the old relay contacts with some fine sandpaper and try it. I have a new one as a back up in my glovebox, but cleaning the contacts worked for me. :)
  • sar1127sar1127 Posts: 1
    I have an 03 trailblazer. Turned on truck last night and both low beams didn't come on. Just replaced both bulbs about 6 months ago when one of them went out. I put the good (old) bulb in to see if it was getting power and the light worked. I put the new bulb back in and oddly it worked. Tried to do the same thing on the other side and when I got the plug off noticed that one of the leads on the plug and bulb were burnt. Why would this happen? Can I just cut off the burnt plug and put on a new one? Is there something before the plug causing it to burn up? Like a relay or something? Or do they over time burn like that? Any suggestions? How or where to get the part? Easiest way to replace or fix?
  • jbs_fancijbs_fanci Posts: 3
    I have an 02 TrailBlazer LT. Shortly after I bought it I noticed the passenger low beam was burnt out. It also had the wires/plug burnt (some sites i've visited state that later years were not made of the same materials & they believed this to be the issue...but I am unsure). My husband fixed the problem on mine. Not too many months later we were driving down the hiway at night and lost all low beams. Not too sure why I did it, but I instantly flipped over to high beams and they worked fine. Pulled over, turned off the suv & restarted it & low beams were back. This went on for a few months. After searching HERE, on Edmunds, we followed the advice of another poster. Here is a copy of the post we read & followed: 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!b> **note that hubby & I left modules #45 & #46 this way & never bought a replacement for either & that was about a year back. I've had no trouble with either device :o) Hope this helps!!
  • bdawson85bdawson85 Posts: 3
    I have an 03 TBLTZ and the driver side headlight went out. When going to change it the light came back on as if there was a short in the connector. The connector is melted and when the light does get connection, the connector gets so hot you can't hold it. I'm assuming I need to just get a new connector somewhere but I was wondering what was the cause of this as well. should I check out the 45/46 relays? Thanks for the help everyone.
  • frstarfrstar Posts: 4
    I have a 2004 TB with 20000 miles.
    After going through all the messages on this subject I may have found the answer in switching the relays #45 and #46. My symptoms are somewhat different(I think). When I park the TB after dark and then start it sometime later, the headlights do not work, neither hi or lo will come on. Last night after driving 2 miles and arriving home(miracle) the headlights came back on as I entered my driveway.
    It(the problem) may be related to the fact that I had parked under some lights before turning the engine off. This is a stretch but had happened before under those circimstances. Very frustrating and scary.
  • bdawson85bdawson85 Posts: 3
    As a follow up, I swapped the 45/46 relays and it didn't do anything different. I think my problem may just be a short in the connector itself. Any input?
  • burdawgburdawg Posts: 1,524
    You should probably replace the plastic connectors with ceramic ones. I did this very thing some time ago when I noticed that the plastic connectors were getting deformed from the heat of the bulbs. Also, I noticed that some corrosion was present on both the bulb and connector contacts, which equals resistance to current flow and more heat. The ceramic connectors don't seem to be an issue. I got them at a local auto supply (Pep Boys) and used butt splices to connect them to the harness.
  • bdawson85bdawson85 Posts: 3
    Ok, thanks. I saw some high heat headlamp sockets on and they have them for several different bulb types. I'll just find out what the OE bulb is and use the matching socket.

    Thanks again for the recommendation.
  • For owners who experience the "headlight dimming" problem described in an older post. Let the vehicle idle for 20 seconds after starting. This solved my problem. Below is the service bulletin that describes the issue in more detail.

    Subject:Diagnostic Information on Headlamps Flicker or Momentarily Dim While Driving #05-08-42-001 - (03/07/2005)

    Models:2004-2005 Buick Rainier
    2002-2005 Chevrolet TrailBlazer
    2002-2005 GMC Envoy
    2003-2004 Oldsmobile Bravada
    with 4.2L Engine (VIN S -- RPO LL8)
    A concern regarding headlamps flicker or become dim while driving may be easily mis-diagnosed. It is very important to capture as much information from the customer as possible. Below is a guideline to assist with diagnostics.

    Verify the customers specific concern.

    • What time of day does this occur (is it light or dark outside) ?
    • What driving conditions (vehicle speed, engine speed, throttle position, etc...)?
    • What was the outside ambient temperature when the condition occurred?
    • What accessories was the driver using when this condition occurred (A/C, heated seats, rear defogger, etc...)?
    • If the concern is at dusk, could it be the automatic headlamps changing from DRL to Headlamp mode and possibly back to DRL again?
    • Are there any other relevant operating conditions?

    Diagnostic Information

    • Service Bulletin - 02-06-03-008A - Info - Low Voltage Display on IP Gauge, Lights Dim at Stop Lights, Battery Discharged, No Start, Slow Cranking, Dim Lights at Idle, Low Generator Output (SI Document ID #1540541)
    • Service Bulletin - 02-06-03-006B - No Start, No Crank, Battery, Batteries, Generator, Gages, SES, SIR, Brake, Security, Theft, ABS, Hot, DIC Messages, Lamp, Light, Battery and Generator Diagnostic Testing and Cadillac Roadside Service (SI Document ID #1563904)
    • Service Information - Exterior Lighting Systems Description and Operation (SI Document ID #826321)
    • Service Information - Battery Inspection/Test (Non-HP2) (SI Document ID #653410)
    • Service Information - Charging System Test (SI Document ID #1468059)
    • Service Information - Inspect for aftermarket devices that could affect the operation of the system. Refer to Checking Aftermarket Accessories in Wiring Systems (SI Document ID #816776)

    • Keep in mind high current draw items may cause a noticeable dimming of lights and a fluctuation in the voltmeter may be noted and is a normal operating characteristic of the vehicle.

    • For 2004-2005 TrailBlazer, Envoy, Rainier and Bravada with the LL8 4.2L engine only, the Secondary Air Injection (AIR) pump activation is thought to be the main contributor to this high current draw condition and is a normal operating characteristic of the vehicle. Refer to Secondary Air Injection System Description (SI Document ID #1298539).

    For customers whose driving habits tend to run the AIR pump diagnostic test that leads to concerns with the headlight flickering, if the vehicle is allowed to idle for 20 seconds prior to driving, this should allow the passive test to pass and prevent from running the active test that may dim the lights. The passive test should/will usually pass 99 percent of the time, and by allowing the 20 second idle period, it should almost eliminate the active test. Be sure to check for codes and correct related concerns if this condition repeats.
    Additional high current draw items are rear window defogger, HVAC blower motor, rear air suspension pump along with other components.
    For easier diagnostics, it may be possible to control or monitor these components with a scan tool.
    It is important to inspect all related connections, grounds and battery terminals for integrity . A loose or corroded connection may exaggerate the concern, and may cause other symptoms. Refer to Testing for Intermittent Conditions and Poor Connections (SI Document ID #1470165).
    Corrections/repairs should only be made for specific concerns identified and not related to characteristic of high current draw components.
  • I have a 04 Trailblazer. I have had problems with my low beam lights going out very often. I take my truck to firestone and when I first started taking it it was over $100 because they had to remove the whole front panel to get to the lights. But now they have lowered the price drastically, but I hadn't had to pay the last couple of times because the light goes out in 6 mths or less which is within the warranty. It is ridiculous!! I need to check the bulb socket the next time to see if this resolves my problems.

    I have experienced problems with cluster panels, low beams, actuators, heating/cooling system, etc. Every problem I have had I came on this forum and it shows people entering tons of problem with the same or related issues. I have even seen reviews from people that has '07 or higher chevy models and they are having these problems and it is ridiculous. I will NEVER buy another chevy/GMC vehicle again. These forums have really helped me to get to the bottom of some of my problems so I could go to a dealership like I know what was going on. But this is ridiculous and chevy does not do a recall on any of this.
  • burdawgburdawg Posts: 1,524
    If your paying them over $100 extra just to remove the "front panel", they are taking advantage of you. It took me about 1.5 minutes to remove the grill (what I assume the front panel is). It just pulls off. Then removing the headlamp assemblies only requires pulling up two locking tabs on each one.
    I replaced both low beam sockets a long time ago on our 02 with ceramic ones due to the heat causing the plastic ones so soften and deform.
  • c118fec118fe Posts: 23
    is there a way to email corporate? Dealer kept putting me off on certified used car and when 12 mo B to B over finally said ok to re-paint my bumpers but being its out of warranty I would pay for rental.Went there 5 x over 1 year including day before warranty expired--We will call you--famous last words.Hoping corporate can help.Grey Chevrolet in Stroudsburg,Pa.
  • cck3cck3 Posts: 1
    I have tried everything. When the key is turned once i have low beam, turn it twice to where everything powers up, fuel pump gas gauge etc.. lights out and will not come back on. I have tried changing #45 and #46 relays all other fuses and micros ok. I drive with highs on all the time.
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