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Discussion Starter · #1 ·
Ok so here is a odd one for ya'll
Replaced timing chain and components as it had lots of slack and causing po 340 and other codes.
After replacing the chain, I figured while in there might as well change cam and cranked and vvt as we all know these are correlated to each other. So after all said and done, start it up and won't fire. Unplug cam sensor and fires up, plug in sensor and motor dies out instantly. So being stumped , I check wiring and all good there. Signal is there and computer recognize signal but once plugged in it dies right out. So now I am stumped. Have new oem cam sensor on order but if not a bad sensor then I am at a loss. Any suggestions?.
 

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'05 Chevy TB EXT
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YEAR - MAKE - MODEL - ENGINE SIZE - CODES PRESENT - TRIM LEVEL - PRODUCTION DATE and be ready to post your RPO sticker if this goes where I suspect it might .....

What was the line on your parts? Chinesium? Amazon "Great Deals" --- ???????????????????
 

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Until chem_man shows up --- let me set this up a little for him ....


.... of course, you did the Crank Relearn Procedure .... right?
 

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2004 chevy trailblazer_lt
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Here I am to assist...

Yes, there is a CASE relearn procedure for the 2008 TrailBlazer with the 4.2L engine. It must be performed whenever the crankshaft position sensor is removed, reinstalled, replaced, etc. ( BTW CASE stands for Crankshaft Angle Sensor Error.)

Here is a link on how to perform the relearn procedure:


Hope this helps and does the trick!

Good Luck!
 

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'05 Chevy TB EXT
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Here I am to assist...

Yes, there is a CASE relearn procedure for the 2008 TrailBlazer with the 4.2L engine. It must be performed whenever the crankshaft position sensor is removed, reinstalled, replaced, etc. ( BTW CASE stands for Crankshaft Angle Sensor Error.)

Here is a link on how to perform the relearn procedure:


Hope this helps and does the trick!

Good Luck!
Here I am to assist...

Yes, there is a CASE relearn procedure for the 2008 TrailBlazer with the 4.2L engine. It must be performed whenever the crankshaft position sensor is removed, reinstalled, replaced, etc. ( BTW CASE stands for Crankshaft Angle Sensor Error.)

Here is a link on how to perform the relearn procedure:


Hope this helps and does the trick!

Good Luck!
I was pretty sure that the CASE Relearn Procedure was required whenever the CPS is messed with - even taking out and reinstalling the same sensor ... but I didn't want to go out on that limb this time. Next time - I'm on it like stink.

Interesting in that ..... the link you sent has a "without scanner" process in it that is remarkably akin to re-establishing the operating parameters for a Ford E4OD transmission whenever the battery is disconnected.

That was a problem with ambulances and fire trucks when they'd turn the battery disconnect switch to "save" the battery from computer drains that happen even with the ignition off.

I got a bunch of comebacks when the E4ODE overrun clutch totally smoked and the dipstick would blow out of the tube so violently that it would put a big dent in the hood and spray the whole undersides in an ATF bath.
One ambulance went on fire when the ATF hit a red hot Cat.​

I had to install a bypass wire for the KAM to operate - and they didn't like it, but it sure was better than smoking the transmission in a few blocks on a hot call to a fire or accident.
 

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Discussion Starter · #11 ·
Here I am to assist...

Yes, there is a CASE relearn procedure for the 2008 TrailBlazer with the 4.2L engine. It must be performed whenever the crankshaft position sensor is removed, reinstalled, replaced, etc. ( BTW CASE stands for Crankshaft Angle Sensor Error.)

Here is a link on how to perform the relearn procedure:


Hope this helps and does the trick!

Good Luck!
When owm part comes in I'll try this procedure ty. Now if it won't start with new cam sensor plugged in I am back to square one. Guess gotta wait till new oem sensor comes in.
 

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Discussion Starter · #12 ·
Here I am to assist...

Yes, there is a CASE relearn procedure for the 2008 TrailBlazer with the 4.2L engine. It must be performed whenever the crankshaft position sensor is removed, reinstalled, replaced, etc. ( BTW CASE stands for Crankshaft Angle Sensor Error.)

Here is a link on how to perform the relearn procedure:


Hope this helps and does the trick!

Good Luck!
Does this apply to my camshaft position sensor also?
 

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2004 chevy trailblazer_lt
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No it does not apply to the camshaft position sensor, only the crankshaft. If it does not start with the OEM sensor, see what codes are present, If none, then you are dealing with a "security module" issue and will likely need to do a relatively simple relearn based on what I've read.
 

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'05 Chevy TB EXT
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GM (typical) --- PassLock Reset Procedure:

Make sure the battery is fully charged because this procedure may take up to 30 minutes and you cannot start the vehicle during this time.

The instrument panel cluster (IPC) --- the BCM and PCM must be in working order and the Passkey system must be working properly.
  • Turn the key to ON and attempt to start the engine and return the key to the RUN position.
  • The SECURITY light will illuminate.
  • Wait 10 minutes until it turns off.
  • Turn the key to OFF for 10 seconds.
  • Turn the key to RUN and attempt to start the engine.
  • If it starts and runs, the system has reset.
If it doesn’t start and run --- then release the key to the RUN position and complete the rest of the steps.​
  • The SECURITY light will illuminate.
  • Wait 10 minutes until it turns off.
  • Turn the key to OFF.
  • Wait 10 seconds.
  • Turn the key to ON and attempt to start the engine and release the key to the RUN position.
  • The SECURITY light will illuminate.
  • Wait 10 minutes until it turns off.
  • Turn the key to OFF and wait 10 seconds.
  • Start the engine.
 

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2004 chevy trailblazer_lt
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You will need to order a new/remanufactured ECM from a dealership part's department, rockauto.com, amazon, etc., and then it will need to be programmed to the vehicle - typically by a dealership's service department or an independent shop that has the proper equipment to program the ECM with the vehicle's VIN and other information so that it will communicate with the transmission module, the Body Control Module, etc. I believe you will need to match up the various numbers on the old ECM's label to the new one.

If I have this all wrong, please someone provide the correct information.

I know that there is a company in the Carolinas that sell remanufactured ECMs, but for every positive review of their work for GM vehicles, I have seen a negative review, so it looks like their "batting average" is 50 - 50. Sorry, but I do not recall the company's name at the moment.
 

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Funny cuz I've replaced my crank shaft position sensor twice without the relearn. Never had any issues.

My truck also cranks, starts, and drives perfect with the sensor unplugged. It takes a little longer to start and no RPM gauge. Otherwise its perfect.

4.2 07 4x4
 

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'05 Chevy TB EXT
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I have 2 ECMs and the one is 'toon'd and the other is stock.

I can switch them back and forth any time I want to --- so I wonder what all the hubbub is all about.

I know if you swap out a crank sensor you need the relearn procedure -- so why not when I change the ECMs?
 

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Discussion Starter · #19 ·
So just got new ecm in and unhooked battery ,waited 30 min , plugged in new ecm programmed to my Vin, hooked up battery and plugged in camshaft sensor. Still no start. Unplug it and fires right up
This is about to go to the junkyard
 

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So just got new ecm in and unhooked battery ,waited 30 min , plugged in new ecm programmed to my Vin, hooked up battery and plugged in camshaft sensor. Still no start. Unplug it and fires right up
This is about to go to the junkyard
So if it works without it, wouldn't that mean there's a problem in the circuit? Ie shorted or an internal short in the new sensor.
 
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