No start no crank

[Danhelperman]

I have an 06 envoy 4.2
No crank
Will crank if jump the relay
No fuel pump
Will pump if hot wired
No injecter pulse
Will fire with fuel spray in intake
So missing 3 things
Crank. Fuel punp injecter signal
Replaced ecm and relearned paslock. Seems to be operating normal and no checkengine light
Any suggestions direction or tests would be helpful
I am a retired mech from old school area but know my way around meter and test light

 

[TJBaker57]

What is the behavior of the security light now?

 

[Danhelperman]

What is the behavior of the security light now?

Key on the light stays on a few seconds and then goes out

 

[TJBaker57]

Well that seems normal enough.

 

[TJBaker57]

This is a good video for the no crank part...

 

[Danhelperman]

Yes i think i have watched all of these videos
I can force everything except injecters but not sure what connects all of them except ecm

 

[TJBaker57]

Have you downloaded schematics? Available in Moosemans signature...

Need service manuals? Get them here!

********* Please note that the FireFox browser has issues with the password handling and that these downloads are not under HTTPS, flagging them as security risks. Chrome and Edge work fine once you allow the download. ********* ATSG 4L60E Manual 4L60E Rebuild Manual 2005 GMC Envoy XUV...

gmtnation.com

There are wiring diagrams for the 2006 model year in there somewhere.

When you "force" things or jump them at the relay...does this mean you have power to the relay contact terminals but the relays are not energizing when they should normally? Or are you supplying power right from the battery? Or maybe you are supplying the ground to the relay coil where the PCM normally would supply the ground? You see there is a lot of detail that can make a difference here...

 

[TJBaker57]

Does the fuel pump prime for a moment at first key on?

 

[Danhelperman]

Understood fuel pump does not prime with key cycle
Cranks if i jump two terminals of the starter relay
Fuel pump i jumped a direct 12 volts to the relay socket that is direct to fuel pump
Have not been able to acess schematics until now
Will look in the links you sent
I know i am missing something and am thankful for the help

 

[TJBaker57]

No trouble at all! I love a puzzle

 

[TJBaker57]

If you have no power to the fuel pump relay socket (a guess on my part since you jumped straight from battery) look at PCM B fuse #10. That is where Fuel Pump power comes from to the fuel pump relay.

 

[Danhelperman]

Will do. When weather clears
Crasy rain right now
Pretty sure i checked all fuses
There is power at the relay batterry voltage but no 10 second burst or key on only power

 

[mrrsm]

This is a Good Video from Eric "O" at South Main Auto Diagnosing a Sketchy Ignition Switch in concert with his Tech 2 showing the layout of the Ignition Switch and the use of the Probe Light "Scope On A Rope" in searching out the Wiring any Ignition Switch Problems:

 

[Danhelperman]

I am fighting my 06 envoy no crank no start again
Any body wanna help??

 

[Mooseman]

Sure but where you at with diagnostics?

 

[Danhelperman]

Sure but where you at with diagnostics?

No ground to start relay
No signal to fuel pump relay
Pump works if jump relat
Starter works if jump relay

 

[Danhelperman]

No ground to start relay
No signal to fuel pump relay
Pump works if jump relat
Starter works if jump relay

Ecm replaced pass lock relearned no codes

 

[TJBaker57]

Have you tested for power at the crank fuse with key in start position?

 

[Mooseman]

Have you tried to diagnose the ignition switch? Checked ALL fuses? Not just pulling and looking at them but checking for power on both posts of each. A no power to fuel pump (no ground signal to relay) would indicate either power not getting to the PCM or a VATS problem but you said the security light is not staying on so that is ruled out.

Are you able to communicate with the PCM using a code scanner?

 

[Danhelperman]

Yes

Have you tried to diagnose the ignition switch? Checked ALL fuses? Not just pulling and looking at them but checking for power on both posts of each. A no power to fuel pump (no ground signal to relay) would indicate either power not getting to the PCM or a VATS problem but you said the security light is not staying on so that is ruled out.

Are you able to communicate with the PCM using a code scanner?

 

[Danhelperman]

I only have a code reader
No codes

 

[Danhelperman]

I only have a code reader
No codes

 

[Danhelperman]

All fuses good with test light swithch off on acc start good

 

[TJBaker57]

If I had tested the crank fuse for power in start position and still had no indications that the pcm was getting a crank signal I would seek to test for power at the PCM, C1-50 with key in start. Power to the fuse does not verify power all the way to the PCM.

 

[budwich]

back up.... you indicate "no check engine light".... when you just turn your key to "ON/RUN", does the check engine light for as long as the key is on?

 

[Danhelperman]

Ok checking now
Help which connecter in the pcm is that pin

 

[Danhelperman]

back up.... you indicate "no check engine light".... when you just turn your key to "ON/RUN", does the check engine light for as long as the key is on?

No only a few seconds

 

[TJBaker57]

back up.... you indicate "no check engine light".

Good catch! I missed that.

 

[TJBaker57]

No only a few seconds

Eagle eye @budwich is onto something here. That engine light should remain on as long as the key is on and the engine is not running. Having that out suggests ignition switch or fuse 28 trouble. Power flow is thru ignition switch to fuse 28 then on to ignition coils, injectors, and PCM as well as a host of other things.

 

[Danhelperman]

Ok fuse 28 is 15amp fuse with powe on both sides in the run position

 

[Danhelperman]

Ok fuse 28 is 15amp fuse with powe on both sides in the run positio

 

[Danhelperman]

Ok guys i will log in next time i work on it
I am thankful for the help

 

[TJBaker57]

Ok guys i will log in next time i work on it
I am thankful for the help

If you have not already done so.....grab the manuals with wiring diagrams from the kink in moosemans signature

 

[TJBaker57]

So I just reread this thread and noticed this question hasn't been asked. Is this vehicle new to you or have you seen it run before? What history can you tell us of the truck and what led up to the current state?

Also noted you earlier said it fired on starting fluid (I'm assuming you then jumped the starter relay) and that would mean fuse 28 and related circuitry is OK as the coils are powered from the same circuit.