[leewayne744]

I have a 02 trailblazer that I swapped engines with a 02 Envoy. Both are 4.2l inline 6 cylinders. Everything works fine all light and dash light only it will not make a sound when I turn the key to crank it. It will not turn over at all. Someone plz help I dont I don't know what else to do

 

[TJBaker]

I have a 02 trailblazer that I swapped engines with a 02 Envoy. Both are 4.2l inline 6 cylinders. Everything works fine all light and dash light only it will not make a sound when I turn the key to crank it. It will not turn over at all. Someone plz help I dont I don't know what else to do

Did you use the same PCM that was in the truck to begin with?

What does the security warning light do when you turn the key to the RUN position only (do not turn to CRANK).

And what does the security warning light do when the key is turned from RUN to CRANK?

Is there no sound from the starter relay in the underhood fuseblock?

Have you double checked all the wiring involved in the swap?

 

[leewayne744]

Did you use the same PCM that was in the truck to begin with? What does the security warning light do when you turn the key to the RUN position only (do not turn to CRANK). And what does the security warning light do when the key is turned from RUN to CRANK? Is there no sound from the starter relay in the underhood fuseblock? Have you double checked allsecurity light comes on then goes off the wiring involved in the swap?

Yes I used the same pcm. Also tried the envoy pcm. Same results. Security warning light comes on when turned to run position and doesn't come on when turned to crank. I changed starter relay. I used same wiring that was already on my trailblazer.

 

[metalmike187]

Sounds like you need to do a CASE relearn.

 

[leewayne744]

How do I do that

 

[metalmike187]

After installing the PCM, most of the time you will need to perform a Security Relearn Procedure. This can be done at your home and requires no tools.

1. Attempt to start the truck by turning the key to the Start/Run position. Try to crank the vehicle.
2. Observe that the vehicle fails to start and the security light is illuminated.
3. Release key to the ON/RUN position (not the ACC position or OFF)
4. Allow the vehicle to sit with key in the ON/RUN position for no less than 11 minutes. Security light will turn off after this.
5. When the light goes off, turn key to OFF position and allow the vehicle to remain in the OFF position for no less than 30 seconds.
6. Repeat #1-#5 for four cycles or until vehicle starts.

NOTE: Since this is a fairly long procedure (35 minutes) I would limit all electrical sources, such as shutting off headlights and AC fans to prevent discharge of battery. It is safe to wait longer than the allotted times above, but it is not safe to wait less.

 

[leewayne744]

I did that multiple times but was told to do the procedure 3 times not 4

 

[metalmike187]

Make sure they key is in the run position and not the ACC position. If it's in the ACC position the procedure will not work.

 

[TJBaker]

If the security light is NOT coming on or flashing when the key turns from RUN to CRANK then I do NOT think you need a security relearn.

Also, a CASE relearn is NOT the same as a security relearn. Two ENTIRELY, different things. The CASE relearn will be neccesary if you use a PCM that was not the one already matched to the engine. Keep the same PCM/engine together and you do not need the CASE relearn.

Does the security light go off after a moment if you turn the key to RUN but NOT to CRANK? Like in this video where I go through a startup in slow motion, pausing at every change of state?

 

[morrissusan640]

I have a 02 trailblazer that I swapped engines with a 02 Envoy. Both are 4.2l inline 6 cylinders. Everything works fine all light and dash light only it will not make a sound when I turn the key to crank it. It will not turn over at all. Someone plz help I dont I don't know what else tTE] After changing my motors from envoy to trail blazer same issue.would even turn over .I had to change fuel pump and check all fuses and relays under hood and back seat .mine had exact same issues..

 

[morrissusan640]

I had same issues with mine It had n9 fire until I changed my fuel pump from the envoy to the trail blazer.also had to check and change some fuses and replays..just got it running after a year of the ordeal..good luck

 

[leewayne744]

If the security light is NOT coming on or flashing when the key turns from RUN to CRANK then I do NOT think you need a security relearn.

Also, a CASE relearn is NOT the same as a security relearn. Two ENTIRELY, different things. The CASE relearn will be neccesary if you use a PCM that was not the one already matched to the engine. Keep the same PCM/engine together and you do not need the CASE relearn.

Does the security light go off after a moment if you turn the key to RUN but NOT to CRANK? Like in this video where I go through a startup in slow motion, pausing at every change of state?

So you are saying use the Envoy pcm with the envoy engine in the trailblazer correct

 

[TJBaker]

So you are saying use the Envoy pcm with the envoy engine in the trailblazer correct

That will make the CASE relearn not neccesary.

It should crank, start and run with either PCM. But switching PCMs in the truck then requires a 30 minute security relearn.

So as far as security goes the PCM and BCM and Passlock sensor in the ignition switch housing get matched up. If any one of those changes you need a security relearn.

For the CASE (Crankshaft Angle Sensor Error) thing, the PCM and engine are matched and if that changes you need the CASE relearn. But this will NOT cause a no-crank or no-start situation.



But if the security light is not staying on after you try to crank then I do NOT think security is the issue.

In that case I think you have a more basic no-crank situation.

Have you tried jumping the starter relay just to be certain the starter motor does work?

 

[leewayne744]

I did jump the starter with the screwdriver and it doesn't work so far everything seems to work except when I turn the key nothing, no sound at all

 

[TJBaker]

I did jump the starter with the screwdriver and it doesn't work so far everything seems to work except when I turn the key nothing, no sound at all

So you just here said the starter doesn't work and then followed by saying everything works except when you turn the key??

And I do NOT mean jumping with a screwdriver at the starter. I am talking about jumping the starter relay that is in the underhood fuseblock.

 

[leewayne744]

So you just here said the starter doesn't work and then followed by saying everything works except when you turn the key??

And I do NOT mean jumping with a screwdriver at the starter. I am talking about jumping the starter relay that is in the underhood fuseblock.

I didn't mean to say doesn't my phone acting crazy I was supposed to say it did work but no I didn't jump to relay I don't know how to do that

 

[TJBaker]

I didn't mean to say doesn't my phone acting crazy I was supposed to say it did work but no I didn't jump to relay I don't know how to do that

Also see this video...

 

[VoyBoy919]

I would say put the original pcm that came with the vehicle. Change the starter and use the one that was originally in the vehicle on the old engine, and recheck that the grounds that bolt to the engine are all on. There's a spot on drivers side front under the alternator (if its a 4.2) that has 2 or 3 grounds that bolt to the engine block.

 

[VoyBoy919]

Also, here's a thought...the neutral safety switch..did you pull engine and trans out together?? did you use the same neutral safety switch if so? The one that was on the car originally? Is the shifting lever correctly installed and is the transmission lever fully forward (park)?

 

[VoyBoy919]

Also..I just had this issue recently on a denali envoy, my good battery that worked fine before my engibe swap got down to 10.9 volts..dash lights all worked, headlights too..and it actually cranked 1 time to start the vehicle but instantly shut off. It's a stupid thing, but usually in my experience these things end up coming down to something minor after swapping an engibe...so maje sure you have a FULL 12 volts.