No crank no start no check engine light. Help

anmr69

Original poster
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Feb 11, 2024
7
Missouri
I had to replace my motor in my 2005 GMC envoy XL due to a valve going into my number one piston. I replaced it with a 2004 trailblazer 4.2 6 l with less miles. I changed out the fuel rail like I needed to and everything hooked up the way it's supposed to. But now I have a no crank no start and I also have no check engine light when I turn my key to the accessory position. My starter is not making any sound at all now and it was working fine before. I did replace the starter relay still got nothing. I'm getting 12.6 off my battery with a multimeter. I checked every fuse that I could think of. When trying to jump the starter with the solenoid it does make a tapping noise and the purple wire on my starter is showing current 12.2. brand new battery bought last year and new alternator. I don't know if it would be the ignition switch but I don't think that that would control my check engine light. The ECM or PCM that's located on the manifold is the original one that's to my truck the only thing I did was remove the wires and remove the housing when we put the new engine in and then I put everything right back the way it was. I could really use some help on trying to figure this out. I'm trying to find out the best way to fix this problem without spending a bunch more money and I'm having to do this myself.
 

mrrsm

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Oct 22, 2015
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Welcome to GMT Nation...

Start by going over EVERYTHING ELECTRICAL, beginning with the Battery Positive and Negative Cables and checking the Starter and Solenoid Connections for Tightness (without over-doing it) and Checking ALL of the Engine Ground Connections on the Driver's Side Lower Engine Block. Remove and Reinstall the PCM Three Color - Coordinated Harness Fasteners and then Check ALL of the Engine Harness Connections...One After The Other.

Last But Not Least... Tighten down the Four Galvanized Connectors that hold the Underside Fuse Blocks to the Under-harnessing...just in case they are LOOSE. Then Use a Lighted Single Wire Probe to Check ALL of the Fuses in BOTH the Under-hood Fuse Box AND The Rear Fuse Box under the Rear Driver's Side Passenger Seat. Remember to STOP after doing each of these actions individually...and TRY TO START THE ENGINE...only after Double Checking the Oil Level in The Swap Motor and then STOP long enough if it even HINTS of turning over long enough to Pull the Fuel Pump Fuse so you can PRIME The Engine Oiling System FIRST. Make certain your Coolant is Topped Off, too. Replace the Fuel Pump Fuse (or Fuel Pump Relay) after a 15 Second Oil Prime Turnover:

TIGHTENTHESEDOWN.jpg

If the Motor Starts...DO NOT RAISE THE RPM ABOVE AN IDLE FOR AT LEAST FIVE MINUTES so you can Eye Ball the Dash Panel for RPM, TACH, Oil Pressure and Water Temperature and also perform an Under-Hood Check for Leaks and Walk around looking for anything Splashing on the Ground. Give the Motor a few minutes to Limber Up. If you go on a Test Drive...Keep it SHORT... and Keep it in the Neighborhood ...and have someone shadow you in a Rescue Vehicle if anything causes the need to Shut Down The Motor for ANY reason.
 

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anmr69

Original poster
Member
Feb 11, 2024
7
Missouri
I had to replace my motor in my 2005 GMC envoy XL due to a valve going into my number one piston. I replaced it with a 2004 trailblazer 4.2 6 l with less miles. I changed out the fuel rail like I needed to and everything hooked up the way it's supposed to. But now I have a no crank no start and I also have no check engine light when I turn my key to the accessory position. My starter is not making any sound at all now and it was working fine before. I did replace the starter relay still got nothing. I'm getting 12.6 off my battery with a multimeter. I checked every fuse that I could think of. When trying to jump the starter with the solenoid it does make a tapping noise and the purple wire on my starter is showing current 12.2. brand new battery bought last year and new alternator. I don't know if it would be the ignition switch but I don't think that that would control my check engine light. The ECM or PCM that's located on the manifold is the original one that's to my truck the only thing I did was remove the wires and remove the housing when we put the new engine in and then I put everything right back the way it was. I could really use some help on trying to figure this out. I'm trying to find out the best way to fix this problem without spending a bunch more money and I'm having to do this myself.
Ok checked everything with Multimeter even ignition wires. All the wires to the ignition show good except one it's only reading 1.8 in the start position it was at 11.8 before I turned to start position. Does that mean I need a new one?
 

mrrsm

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If you mean replacing the Ignition Switch... Only after you investigate the Videos on YouTube posted by @MAY03LT (MAY03LT) under the Topic(s) of "No Start - No Crank" (or Vice-Versa) and follow along on his explanations of using his Start Wiring Diagrams to explain what to look for and what to Test for during his suggested Diagnostic Routines.

In one of those, he covers the aspects of using an OEM Replacement ACDelco Ignition Switch. Also... Check on Eric "O"s SMA (South main Auto) Channel for the same On Topic Videos for investigating Ignition Switch Issues with a Lighted Pin Probe and using a Tech 2 for Trailblazers and Envoys as these deal with the Ignition Switch Wiring probing tests as well.

If you also perform a Basic On Topic Search here at GMT nation using the search string " No Start No Crank"...there are myriad On Topic Threads with more contributions from many other talented Members as well.
 

mrrsm

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Well... If the Low Voltage Reading is NOT what is expected...it can also be due to having the Ignition Switch Outer Teeth misaligned by a Single Tooth on the Switch Cog rather than from having a completely Bad Ignition Switch. There are a LOT of Threads here and likewise similar Videos available to check out that possibility on YouTube as well.
 

Mooseman

Moderator
Dec 4, 2011
25,192
Ottawa, ON
Did you keep the original 2005 pcm? If you're trying to use the 2004, it could be the cause. Because you're not getting a CEL, I suspect power is not getting to the pcm. Check ignition switch outputs.

I would also recheck your ground wires to the block since you can't even crank the engine jumping the starter relay. I had a similar issue when my ground wire at the block turned to green pus.

Reread your post about the CEL, it's not supposed to come on at accessory. At RUN, it should come on.
 
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anmr69

Original poster
Member
Feb 11, 2024
7
Missouri
Mooseman - No it's mine original PCM that came with my truck. And I checked all four wires go into ignition switch they all showed the same power level at 11.8 yes I know my battery was going low but for testing purposes I was able to get the same numbers then when we checked each one of them going from accessory to start I lost one feed to 1.8 it's a yellow wire.
 

Mooseman

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Dec 4, 2011
25,192
Ottawa, ON
But make sure power stays on the wires that are supposed to stay on while cranking. Documented cases of the power dropping out when turned to CRANK, killing the PCM and preventing cranking.
 
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anmr69

Original poster
Member
Feb 11, 2024
7
Missouri
Well there was only four wires all of them showed 11.8 in accessory but only one of the yellow wires showed 1.8 when I go to the start position so I did go out and get a new ignition switch I'm going to try to change that out as soon as it quits raining.
 
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Mooseman

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Dec 4, 2011
25,192
Ottawa, ON
IIRC, the yellow wire is the crank wire. This video explains the issue.

 
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mrrsm

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It will also be worth checking out the Two Videos coming from Paul "Scanner" Danner's Automotive Training School up in Pennsylvania in the 2nd Video on the procedures for conducting a "Voltage Drop Test" explained in universal terms in this Video as a Positive to Positive measurement of the Difference in the Electrical Potential along the SAME Wire on a LOADED CIRCUIT. The same Test applies for a "Ground to Ground" examination of this issue:



 
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mrrsm

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I forgot to mention this earlier... But the Park Neutral Safety Switch being *Maladjusted* might be the Stopping Block here as illustrated below:

4l60e-neutral-safety-switch-wiring-7-1861172270.jpegPARKNEUTRALSAFETYSWITCH.jpgs-l500.jpg

There is always a "Sweet Spot" that tells the Brake Pedal Switch that the 4L60E Position Pawl is either DEFINITELY in The "Park" Position or DEFINITELY in the "Neutral" Position before the Key will Activate the Starter...
 

budwich

Member
Jun 16, 2013
2,021
kanata
I would also recheck your ground wires to the block since you can't even crank the engine jumping the starter relay. I had a similar issue when my ground wire at the block turned to green pus.
The fact that you can't jump the STARTER SOLENOID (right? and not the starter relay) and cause the starter to run is probably the best place to look at things..... no keying is involved and the electric path is very simple. Basically, only a power and ground. One coming directly from the battery and the other from a ground point (other than the battery).. This is assuming the "jump" was done properly AND the starter is indeed good. Please describe your "jump technique" in terms of wire points / colors as your earlier description about "the purple having 12v" is somewhat unclear. The purple should only have 12v when the starter relay is jumped. The red at the starter should always have 12v.

Of course, the question is: "is the starter hooked up correctly?" :smile:
 
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mrrsm

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...and it follows that if the Donor Motor came from a "Rust Belt State" with the Former Owner's Starter still installed ... there are THREE Ferrous Metal (Steel) Fasteners that hold the Solenoid Power Wire and on the TWO Heavy Positive Cable Post locations in place that can lose their Cadmium or Zinc Coatings via Road Salt Exposure and get seriously "Gnarly" and Rusted or Corroded to the point of NOT being able to Carry any Current Flow as shown in this image:

GNARLYSTARTER1.jpg
 
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anmr69

Original poster
Member
Feb 11, 2024
7
Missouri
Changed out the ignition switch and starter still nothing. I think my biggest issue is the no check engine light but I've got to charge up my battery before I can check all my PCM connections again so I'm at a loss here. I've never had this problem before.
 

budwich

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Jun 16, 2013
2,021
kanata
I guess that means you aren't jumping at the starter but jumping the starter relay in the fuse block.
 

mrrsm

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Given that there are so many Threads that cover "No Crank No Start" issues... Historically... THIS one is worth the trouble going through very carefully. Pay particular attention to the contributions that were made by @budwich and @coolasice for the proper Starting System Diagnostics. The OP does eventually figure out what went wrong...with their help:

 
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Mooseman

Moderator
Dec 4, 2011
25,192
Ottawa, ON
Don't forget your ground wire from the battery to the block as well as the positive battery cable. Check that power from the relay is getting to the starter solenoid when you jump it.
 
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anmr69

Original poster
Member
Feb 11, 2024
7
Missouri
Given that there are so many Threads that cover "No Crank No Start" issues... Historically... THIS one is worth the trouble going through very carefully. Pay particular attention to the contributions that were made by @budwich and @coolasice for the proper Starting System Diagnostics. The OP does eventually figure out what went wrong...with their help:

Thank you for this I have read through each and every post and taking some notes on some things to try on a different note I did take the starter off and had it taken to O'Reilly's it wasn't hardly turning over very much at all so I did go to U-Pull-It and bought a different starter that works great I'm going to put it on tomorrow. I brought a brand new ignition made sure that it was in the correct position. Tomorrow is going to be a day of finding and cleaning and disconnecting and reconnecting all ground wires. And checking netural safety switch. But on a side note my tail lights come on when I have it in reverse and I can move the motor when I move the crankshaft.
Don't forget your ground wire from the battery to the block as well as the positive battery cable. Check that power from the relay is getting to the starter solenoid when you jump it.
I will check everything again tomorrow. Again thank you all for helping me.[/url]
 
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