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2006 chevy trailblazer_ls_ext
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Discussion Starter · #1 ·
I think I had this posted in the wrong section, I will repost it here:

My 2006 Trailblazer 4.2 L won't crank/start. The car is driven regularly. Some unusual symptoms:
1. Cannot crank the starter with key....Battery directly to the solenoid will crank (but not start) the engine.
2. Cannot establish a link with the PCM using my my code reader, after scanning for some time it says NO LINK or something to that effect. The code reader worked just the other day however.
3. With the key in RUN position, (or any position for that matter), the horizontal indicator line under P-R-N-D-2-1 dash display is not illuminated at all (i.e. the transmission can be shifted to any gear, but there is no indicator line beneath the display to show what gear it is in).
4. With the key in RUN the reverse lights do NOT illuminate in any transmission position. HOWEVER..The reverse lights DO turn on when the key FOB button is pushed (as it normally does for providing illumination while unloading).
5. In the engine compartment fuse block, I can verify correct operation of the Starter relay [47], and the adjacent Powertrain relay [57]. (to clarify, I pulled them out and checked that they function correctly...not connected to vehicle) I also checked most of the fuses. Also, Checked most of the fuses in the rear underseat fuse block.

The battery is not in excellent shape but it had no problem cranking the engine when I jumped directly to the starter solenoid. Ive had it on 2Amp charge all day to make sure I could run thru all the tests without running it down.

I Replaced the ignition switch in the hope that it would fix the problem after reading thru Trailvoy comments, but the problem is unchanged. I assume I set the teeth correctly....The key moves thru ACCY, RUN, and bounces back from the START position.

After hooking up the battery after changing the ignition switch, I went through the extended PASSLOCK relearn procedure, as descibed somewhere in this forum. It did not do anything. (The first time I tried it, I accidently left the lights on during the procedure and ran the battery down. Its been on 2 amp charge since then)
I looked at the transmission position indicator switch, it does not appear to be damaged, I might remove it to inspect it more closely.
Yesterday we had an electrical storm, and there was a real loud strike from the direction of the driveway where the vehicle was parked. However, I have found no physical evidence whatsoever of a ground strike near the vehicle.

This is my wife's vehicle, and she needs it for work tomorrow!
 

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2006 chevy trailblazer_ls_ext
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9 Posts
Discussion Starter · #2 ·
Trailblazer NO CRANK followup to above post.

I might have discounted the idea of a lightning strike to hastily, approx 75 feet from where the vehicle was parked, a 16-inch Oak was hit and blew off the bark along the edge of the tree. Still though, thiat seems kind of far away to have caused the problem. And I still cannot figure out what the problem actually is.
 

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2006 chevy trailblazer_ls_ext
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9 Posts
Discussion Starter · #3 ·
2006 Trailblazer EXT Wiring Diagram for pcm

Would anyone have a image of the wiring diagram for the pcm? I am going to try to trace back as many wires as I can.
 

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2006 chevy trailblazer_ls_ext
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Discussion Starter · #5 ·
So you first discovered the no start problem after the electrical storm? In my opinion that is too big a coincidence to not be related.
True. The tree which was struck is 70 ft from where the vehicle was (and still is) parked. Still, whatever the cause, I still need to diagnose the problem. I guess I need to verify that all the major power and ground pins for the PCM are working correctly before I can
declare the PCM dead.
 

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2004 gmc envoy_sle_xl
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Unless you have intimate knowledge of how the PCM works and can probe the wiring harness, you are looking at a huge task. Why not see if you can find a PCM at a salvage yard that is from a similar model and try replacing it.
 

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2008 chevy trailblazer_lt
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300 Posts
In general, no crank no start problem are usually wiring related. Since you have checked out the starter directly jumping things, it appears a bit more further down (ie. control wiring conditions). Since you also appear to have status light issues along with some PCM "talking" issues, this is suspicious.

First question and check always, is your PCM getting power and is happy. The simplest way to do this is turn the key to ON and leave it there. The check engine should come ON (plus others initially... bulb checks) AND stay ON FOREVER (ie. as long as your key is in ON).... leave it there for 2-3 minutes to see what happens. Go from there, check the operation of the starter relay and fuel relay.
 
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