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Discussion Starter · #1 ·
So, the title says it all (almost).
Also, see attached image at bottom of post.

While on vacation, I noticed a new rattle in my door, and couldn't figure out what it was. One night I tried using my key to unlock my driver door, rather than the keyless entry fob, so that the lights wouldn't come on. Well, it just turned freely, but wouldn't unlock the door. The electronic one worked, so I didn't think much of it, and planned on repairing it soon. Well, now the actual key receiver thingy fell into the door. I can hear it moving around in there (LOL).

So, my question is, what do I need to do this repair? I am mechanically inclined, but have no clue what the actual parts would be called. I am also aware that working on door panels can be frustrating, and often damages door panels, so any trailblazer specific advice for door panels is appreciated.

It's a 2003 Trailblazer LTZ 4x4.

Thanks in advance guys

2004 chevy trailblazer_ls_ext
404 Posts
This guy does a pretty good job of explaining how to remove the door panel:

The only thing I would do different is I would not pull on the outer edge of the inner door handle surround. Use a small flat bladed screwdriver and push the clips down. Insert the screwdriver between the door handle bezel and the surround where the clips are located. Take a look at it and you'll see where the clips are. It just pops back on when you're done.
I can't help much with the lock question, though! :(

2007 chevy trailblazer_ls
343 Posts
Removing and reinstalling door panels is easier on these vehicles than others I have done. Lots of videos around. As far as replacing the door lock cylinder, I haven't done that or seen directions but there are videos of it being done on other GM vehicles such as From that you should have some idea what is involved after you get the door panel off at about the 10 minute point.

2,018 Posts
The lock cylinder wears out and falls into the door on many GM vehicles (like MINE DID!) .... but there's more to it than just a mechanical repair.

You'll need a new cylinder, keyed to match the ignition key....natch!. Locksmith-time!

If the cylinder fell into the wrong location .. the window can make a mess of the control rod ... this can be a big problem!
Actually ... the "if" part is rather diabolically inaccurate ... it WILL bend the rod ... count on it.​

The length of the relay rod is critical and the window will bend the rod in a pattern that 1. will be too long or too short ... and 2. with (new) incorrect bends in it.
The bends are critical as the rod still has to be out of the way of the window motion and at the same time, be the correct length.​
The furtive motion(s) include:​
1. Assemble​
2. Test.​
3. Not right!​
4. Disassemble, dropping plastic clips into Never Never Land.​
5. Bend rod.​
6. Reinstall rod after finding plastic clips​
7. Retest lock and window up-and-down for interference test.​
8. Not right again!​
9. Disassemble again, losing plastic clips into Never Never Lsnd again.....​
10. Repeat parts 1 through 10 several times.​
11. "Drink beer" and "change Band Aids" should be inserted after #s 3, 4, 5, 6, 8 and 9.​

I just did this very same repair and that rod is a hair-pull as I had to assemble it repeatedly 《see list above ... and note below》until it was correct ..... then....

..... my lock sensor had failed in the first destructive when the control rod was mutilated by the window going down. I also believe the UNLOCK solenoid failure (no longer available) was given the 110% over-motion test.

Note that I say UNLOCK because although you can LOCK the door mechanically, it will require a working solenoid and lock detection sensor to UNLOCK the door.

Amazon states that both the latching mechanisms and solenoids are identical on the left front and rear doors. It doesn't matter since they are unobtanium anyway.
Dorman also had a listing for the solenoid, but it's NA.​
Strangely, WalMart has a listing for it, but it's also NA.​

Then there's the LOCK POSITION SENSOR in the door lock mechanism itself .... no longer available ... but you need one anyway.
That's harsh.​
It's also an integral part of the door LATCH ASSEMBLY... harsh part here: which is no longer available either.​
I found a YT on replacing the sensor on the door latch mechanism by releasing the spring band retainer.​
Good news if it were available!​

All this is wrapped up in the demented operating system that allows you to turn the key to UNLOCK one time to just unlock the driver's door and not turn on the interior lights. The doorlock position sensor tells the computer the number of times the key is turned ... it does!
Did I mention that the lock position sensor is not available?​
NOTE: IF the solar detector thinks it's dark, the front interior lights will come on anyway with the one-time key motion.​
---> For the record, I had no idea the front and rear interior lights were driven separately! Whodathunk?​

The next part is complicated by the fact that you also absolutely NEED a new door lock position sensor (it's no longer available) to allow you to turn the key to UNLOCK twice, unlocking all the doors and the tailgate and turning all the interior lights on.

《 note》 all this diving into the door ... repeatedly ... will leave your arms bleeding and as a bonus ... you know that evolution is a farce because try-as-you-will, you cannot grow an eyeball on your fingertip to be able to see what you're doing inside the door.

Then .... to brighten your day some more .... if you cannot find a good, used doorlock position sensor... you will totally rely upon the keyfobs working 100% of the time and that you never get a dead battery?
That's dark.​

However ... an infinately small beam of sunshine is possible IF you attach that floating red wire under the hood, next to the fuse panel so you can st least charge your battery through the 7-pin trailer conex next to the hitch.
DO IT NOW .....​
Think about that for a few moments .... if you need clarification, let me know.​
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