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Chevrolet TrailBlazer Electrical Problems

HI I have an 02 Trailblazer,..I am now having some weird problems and was hoping someone might have some insight to help me on this forum.
Truck was running fine,..I use my truck for work. So I take things out of the back of my Tailgate all day long. Well it started when I opened my tail,..and I looked at the dash and I had lights on and the radio went off? Well when I slammed the tail..the lights went off on the dash and the radio came back on.
So then a day came when it started raing...thats when the all the idiot lights came on in the dash.. The car continued to run and the speedomter worked, but the power windows did not, neither did the gas gauge,oil,battery,air conditoner,power locks and back wiper. or radio. Next day the rain stopped and everything worked fine. Now its only when it rains..I lose power to everything I just mentioned but the headlights and tailights still work.
I had someone put it on a computer to get the codes, the codes go to the tailgate control module. Not the one behind the driver seat..but was told its the one in the tailgate itself.
I then had someone who had access to a Tec 2 ( GM Tool) see if it would come up with anything. They said they found the errors...but the Tool could not communicate with the Tailgate Module??My question here is has anyone had this kind of problem,..and do you think it sounds like the tailgate module is the problem....or is there somewhere else I should check before I spend the money on a brand new tailgate module??The thing that is fishy is that i was told that the body control module ( behind the drivers seat) controls some of those idiot lights,..and the tailgate module controls the others? I had the Tec 2 communicate with the body control module and it couldnt communicate with the rear tailgate...which is why I am so pluzzled? One GM Mechanic told me to put in a new ignition switch as thay have that problem all the time at the I did...still have the problem? Anyone??
thanks in advance


  • burdawgburdawg Posts: 1,524
    Since you use the tailgate a lot, and the problem first occurred when you were opening/closing it, have you checked the wiring harness between the body and the tailgate?
  • I did check the harness. I opened the rubber seal and pulled out the wires harness to look for a split coating on any of the wires or a splitwire...everything looked fine?? The next when it started happeneing more often. And now I am stuck with anytime there is any rain....or if I am out and it starts to a matter of minutes " Bam"...the lights come on the dash and I lose power to the windows and radio, airconditoner. When it first started happening it was once in a while but ever since I opened the harness up,.. it now happens like clock work.
  • burdawgburdawg Posts: 1,524
    If that's the case then it's possible the harness is still the problem, but in an area you can't see, like at a connection point. Since it happens during wet weather and became worse after checking the harness then I think I would try to find out where the connectors are for that rear harness and inspect them for corrosion or other contact problems.
  • I have a 2003 Trailblazer EXT that required a battery replacement today (Surprise, suprise, Gomer!) ... Now, the radio doesn't work, the interior lights won't come on and there are a couple other non-functioning electrical devices.

    Is there a reset button or something that I missed?
  • tblazedtblazed Posts: 945
    Sounds like either the BCM got glitched during the battery change since it controls the things you mentioned, or maybe the 125 Amp "Mega Fuse" on the underhood fuse block got blown somehow since it supplies power to the interior and most of the accessories, maybe frrom someone hooking up jumper cables wrong? (Been known to happen before). I would check that big 125 A fuse, and if it's good (12 Volts on each end of the fuse) then try disconnectiing the battery for 35 minutes to reset everything, reconnect the battery and try again.
  • Hi there does anyone have legal advise on how to get the previous owners to reinstate the extended warranty... :lemon: I have a 2003 TB love it, but the engine light stays on, it went off but it keeps coming back on, and it has a vibration at 45 to about 60, I tried several things for the light but it keeps coming back on.. the previous owners told me that the light never came on while they drove it, and that they were not aware of the vibration while its so damm obvious.. I was doing the extended warr. transfer over to my name since it had almost 1 more year left on it, and I was going to take advantage of the extended warr to have the dealer find the problem... but the previous owner told me i could change the extended warr to my name w/out any problems... but to my dismay they canceled in Oct :surprise: . I got the truck from them on the 18th of oct.and at that time they told me it was active and I could have transfered over. :surprise: so does anyone know if I have any recourse againts the previous owners.. or am I out of luck... I called them, so now is just a waiting game to see if they will even call back, since I am financing the truck thrugh the credit union maybe they can do something about it?? since the light keeps coming on, or is it basically I am out of luck, I bought it as it was so I may be stuck with a lemon.....

    any ideas or comments....... :lemon:
  • 2002 TrailBlazer. I had left my 4 ways on for about 20 minutes. Upon shutting them off my truck went dead. I had to boost it. it ran. The next day I had to boost it as well. It ran for 30 minutes then I went to drive away and I had 2 lights on, a engine light with an arrow pointing down and the transmission light. My truck idled at 1100rpm but when I gave it gas it would not accelerate. It goes into gear but does not move. No fuses have blown and all gauges read accordingly. What is wrong? Can I fix it by unpluging my battery for 35 minutes?
  • meg8meg8 Posts: 1
    My keyless entry and rear wiper stopped working. I stopped at the dealer and after hooking up to their computer they said my tailgate module was bad. Is this common to the trailblazers? I only have 38,000 miles, and this is only one of the MANY problems I have had with this vehicle. Any advice on the difficulty of repairing/replacing this item myself? Also, I haven't been able to find this part online. Anyone have a part # ? Thanks
  • I had a problem with the battery on x-mas night. I replaced the battery the next day and now notice something I haven't noticed before. When the truck is on and in park, with eth lights on and the heater running, it will loose RPMs and then rev itself up to avoid stalling. I understand why it's doing this, but never noticed it before. Is this common, or should the engine maintain itself better? Is my alternator defective?

  • The lights on about a quarter of my radio controls went out a while ago and now another quarter have joined them. Is this a fuse, bulb, wiring or what that causes this? Is there a simple way to get at the problem and correct this myself? The radio, cd, etc still functions fine, it's just a problem changing things at night. Any suggestions?
  • The seat belt light no longer illuminates when starting the vehicle and the chime no longer functions with the seat belt off. The chime still works with the key in the lock but not for the seat belt. Fuses seem okay and the maintenance manual is quite vague on what to do. Any suggestions?
  • I have a 2006 chevy trailblazer and I just picked it up from the garage, as they had to change the fuel sending unit in it because my gas gauge was not working, so on my way home from there all my gauges dropped down to zero and do not work anymore, I pulled over to stop and restart the vehicle thinking the computer didn't think properly upon starting and all was fine till I reached 50km/h and then my gauges dropped back down to zero, so again I pulled over to restart the vehicle and all is good till I reach 50km/h and everything stops working, I have no speedometer, gas, rpm, oil, temperature gauges at all. I went online and did a self diagnosis and it told me it could be the fuse is blown, but I wouldn't think the gauges would be okay for a bit then stop working if the fuse was blown, or it said it could be the Instrument Panel Voltage regulator is bad. Now they did also replace 2 fuel line retainers because as they took the tank off the lines broke. Hope you can help. Gisele
  • jntjnt Posts: 316
    The problem you described is limited to the radio itself, not the vehicle system. There are two likely causes:

    1. Light bubs under radio switches went out.
    2. Electrical circuit that hooks up to the light bulbs is bad

    Changing fuses will not help

  • I'm having the same problem with my wife's 04 Envoy. Some of the radio lights are out. Dealer says the fix is a new radio. Not at close to a grand it isn't! The lights came back on briefly after hitting some bumps, but are off again. That tells me it's a connectivity problem. But where? Can the radio be opened up? I imagine it's a pain to pull out of the dash.
  • Wish I had that problem! But that's because I hate wearing seatbelts!
  • My wife has a 2002 TB.About a month ago it wouldn,t start when she was leaving for work, battery was completely dead. Had the battery checked and checked out good.Charged battery and put back in and the same thing happened within two days! Took my good battery out of my truck which i knew was good and it drained down in three days. Had alternator checked and was also o.k. Something is staying hot and draining battery, but i can't seem to find it. There is 4.5 amps draining from the battery when we checked it last night. We pulled every fuse front and back while the tester was hooked up and nothing! Just wanted to know if anyone else has expierenced anything like this before? Thanks.
  • burdawgburdawg Posts: 1,524
    Yes, I have. Not in my TB but it has happened to me before. This is where you need a good electrical schematic to find out what if anything has inline fuses that may be hidden or out of the way. Add to that once you find the spot in the circuit where the load disappears when it's disconnected it helps to find any branch circuits from that point on.
  • I am having the same problem...Looking for a answer before i go spend $$$$$ at the dealership
  • I also have a 2003 Trailblazer that the speedometer is malfunctioning at random times. The needle will reed incorect speeds on some trips and work fine on the next. A dealer quoted us $400 - $600 to replace the speedometer to see if that would fix the problem. This is rediculious that they have recalled the speedometers on the sister vehicles with the same issue but refuse to take care of this issue.

    I have been a long time GM customer but I am now considering replacing my Chevy with a foreign fullsize (they seem to stand behind their product better).

  • I put the 4wheel drive to the AWD position,it switched over to AWD but then the lights started flickering on the dash and the 4wheel drive kept engaging and disengaging even though the tires were not spinning. I put the truck in 4Hi and all trouble went away. The next day my wife put the truck in AWD and the service 4wheel drive light came on, she parked the car at a store and when she went to leave she started the truck and it would not come out park,the dash lights wouldn't work, the blower didn't work,only the radio and headlights would come on(and we had troulbe getting the key to turn off). I put the 4wheel drive switch back into 2Hi and it would not switch over, I tried the same with 4Hi with no luck. After about 1hr of starting the truck and turning it off, diconnecting the battery and pulling many fuses the truck finally went back to 2Hi and all the trouble went away. I've been experimenting putting the truck through all the 4wheel drive modes and everything thing seem to be alright, then yesterday when I put it in AWD the dash lights went out again and the AWD system was engaging and disengaging(pulsating)even though I was on dry pavement. I tried to put it back in 2Hi and it wouldn't switch over, then I put it in 4hi and it switched over and everthing worked fine again. When I switch from 2Hi to 4Hi I don't have any trouble it's only in the AWD mode. No codes are stored on the computer. Any help would be grateful.
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