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2005 chevy trailblazer_lt_ext
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7 Posts
Discussion Starter #1 (Edited)
I am having a no crank issue on my 2005 TB, chasing down a bunch of different possibilities. But here's one:

The self-test that is supposed to illuminate all of the yellow and red lights on the instrument cluster does not occur when I turn the key to Run. I hear normal sounds of a fuel pump and a few other miscellaneous things, and the radio, fan, and power windows work in Run. But it won't start and none of the cluster lights come on except the MIL (orange check engine light/CEL) and the red battery light. (I have a charger on the battery, which is still good.)

I do get a key-in-ignition, driver side door open "BING" "DING" warning bell that sounds like it is operating normally.

So... ground? PCM? Wiring chewed by rodents? BCM? Security problem? Ignition switch?

I stated in another thread that this has been intermittent over the past 6 months... until today. :suicide:
 

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2008 isuzu ascender
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977 Posts
My guess would be the ignition switch itself which is a weak point on these cars .
 

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2005 chevy trailblazer_lt_ext
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7 Posts
Discussion Starter #3
Broken still, but working

My troublehooting indicated that it didn't appear to be the ignition switch, however I believe that the PCM does have an input that senses the key position, and I thought maybe that untested wire could be bad.

In any case, I replaced the ignition switch, set it up to the same position as the old switch (and the same position pictured in the thread about it) and the truck still won't start. It has the exact same indications. Nothing changed.

Since I was tired of tracing grounds and frayed wires, I had a mechanic come tow it to the shop. When they started working on it, they were able to start it on the first try.

My problem now is that I don't want the truck back until it breaks again and he can test it while broken. When he called and recommended replacing the starter, I rebuffed him, :bonk: :nono: reminded him that the self-test lights don't energize when it's in the broken condition, and reminded him that I was able to jumper the start relay to test the starter while it sat at my house broken. While I had it, the starter would energize but the vehicle would not start and run. I think it's the PCM going flaky. I wonder if he knows how to open one up and look at the circuit board.
 

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2005 chevy trailblazer_lt_ext
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7 Posts
Discussion Starter #4
HELP!!! Still broken!!

My Trailblazer still has this problem. After my March 2018 reply, the symptoms disappeared for a month or two, reappeared in the summer a few weeks, and it has been mostly starting until recently.

Can anyone tell me what would cause all of the indicator lights (over a dozen) to not be tested? What sends that self-test command to the dash display, and what would stop the vehicle from doing it? BCM? PCM? Grounds?!?

Because, as soon as the self-test lights illuminate while the key is in RUN, I can start it
. Sometimes I wiggle the key a bit (but that seems to be a placebo) and it works. Sometimes I wait with the key in RUN for 30 seconds or 8 minutes and the lights appear and it starts. Sometimes I play with the neutral/park shifter to see if it's a neutral park switch issue.

This is so intermittent! Sometimes I can start it on 1 try, other times I attempt 600 key off/on cycles and it doesn't ever work and I drive another vehicle.

I have recently been disconnecting the battery for minutes or hours to reset the PCM. Again, it's a placebo, but sometime it works on the 5th key turn.
 
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