NEED HELP 2004 trailblazer 4.2 cranks but no start

[warriorpluto]

Tried everything. There is no spark at the coils. I checked coil harness and it's good. Checked all fuses. Verified timing on chain. I haven't changed pcm yet nor the ignition switch. Would the ignition switch cause no spark at the coils? Also no codes except for data link failure but I think that was because another mechanic was trying to diagnose. Anyone else came across this problem before?

How do I check the coils with voltmeter

 

[budwich]

you need to check to see if your PCM is getting voltage (and ground) appropriately. Further, with the key just turned to on, does your "check engine" light stay lit "forever"... that is. for as long as the key is left in the on position. My guess would be "check all your fuses".

 

[Mooseman]

There are tons of threads on this subject:
https://www.google.ca/search?newwin...i10i30k1j33i22i29i30k1j33i160k1.0.BGip_FeIsyc

 

[warriorpluto]

you need to check to see if your PCM is getting voltage (and ground) appropriately. Further, with the key just turned to on, does your "check engine" light stay lit "forever"... that is. for as long as the key is left in the on position. My guess would be "check all your fuses".

I thought this was an 2004 . It's an 2003 . The check engine light does NOT show on the gauge. It read great with my bootleg tech2win and one readers

 

[budwich]

not sure I follow the "story"... at the start, you indicate that the PCM was not "readable"... now you say that you can read / communicate with it.... ??? Next, you appear to be saying that there is NO check engine light on the gauge... implying something to do with 2003 or 2004 model year????

First, the check engine light is a requirement.... it must at least light during a key on "event" as part of the "check instrumentation lights" to ensure that all lights indicators are working. IF it doesn't light during that event, you have a bulb issue at the very least. Further, as I indicated with a "key left in the ON" position, the light should light and stay lit for the entire time. IF that isn't happening, then your PCM is not is a "good state". Of course, if your light is out during the "check light" test, then you would never know what state your PCM is in. Again, check your fuses with a meter to ensure the proper conditions exist (battery where battery is supposed to be).

 

[16vcabman]

Check fuse 28 this runs the coils

 

[warriorpluto]

All of that is good. What are these wires and where do they go? I see they are cut.

These here

 

[warriorpluto]

Here's another clear picture.

 

[mrrsm]

I inverted your single image...and Zoomed in on the Nylon Fabric Wire Bundle Label to better read what it says,,, Take a closer look/photograph it as to what you can see and determine if you can read more information off of that Label. Also ...advise as to whether or not those wires look damaged... or if they were cleanly cut by some errant Installer during an attempt at putting anything "After Market" (Radio...GPS, HUD...Wireless Entry, etc,) down under there. Here is what I can make out so far:


Dk Blu
Orn
Blk
Lt Blu

 

[coolasice]

I inverted your single image...and Zoomed in on the Nylon Fabric Wire Bundle Label to better read what it says,,, Take a closer look/photograph it as to what you can see and determine if you can read more information off of that Label. Also ...advise as to whether or not those wires look damaged... or if they were cleanly cut by some errant Installer during an attempt at putting anything "After Market" (Radio...GPS, HUD...Wireless Entry, etc,) down under there. Here is what I can make out so far:


Dk Blu
Orn
Blk
Lt Blu

View attachment 85085

Brake controller wiring.

 

[mrrsm]

Good Find @coolasice ...So if the need to "Press The Brake" first in order to start the vehicle... is shunted by this issue... Then the SUV will not do anything... yes? OP... I hope this cut-bundle has been caused by an accident and not something done intentionally by anyone... Keep your wits about you if you are presently in conflict with anyone.

 

[coolasice]

I

Good Find @coolasice ...So if the need to "Press The Brake" first in order to start the vehicle... is shunted by this issue... Then the SUV will not do anything... yes? OP... I hope this cut-bundle has been caused by an accident and not something done intentionally by anyone... Keep your wits about you if you are presently in conflict with anyone.

It comes cut like that from the factory..

 

[budwich]

further perhaps a little history about the vehicle might help.... did it ever run while in your possession? It so, what happened to get it to where its at now?

 

[warriorpluto]

further perhaps a little history about the vehicle might help.... did it ever run while in your possession? It so, what happened to get it to where its at now?

Well it's been a while since I've been on here. I still own my envoy Denali. I sell cars now and had this particular trailblazer on rent to own. The customer says the the trailblazer just shut off while he was driving. I don't know how true this is though. Thats why I tore everything apart to see if the wiring was damaged. I did get a code saying lost communication to IPC. I don't know what that means. I've tried and verified everything. Has fuel but no spark. I doubt all coils could die at the same time. Could harness is good and main harness. Great fuel pressure. Great compression. Changed ignition switch and no change.

All fuses are good front and rear. Only thing now is to swap pcm from another vehicle and hope it starts. I tried to read the label but as I folded it back all the letters came off and most of the folded part was faded

Crank sensor had also been changed to times and wiring is good from there also

 

[budwich]

thanks for the "history". You still need to investigate why you have no "check engine" light during initial key on light test sequence and thereafter with just key left on. That is an indication that the PCM isn't happy. You should be able to also see 5v going towards the coils / plugs during cranking using a light tester / meter.

 

[Mooseman]

IPC=Instrument Panel Cluster. It could be dying and throwing bad data into the databus. Could explain why no CEL. Remove it and try to start it. Or replace it with a known good working one.

 

[warriorpluto]

Thanks guys. I'll look into it tomorrow and take the cluster out and see what it does. Meanwhile here I've just caught a thief on my camera while I'm laying in my bed. He stole a wheel off a G6 I have for sale. I'm sure if he wasnt interrupted he would've gotten all four. I chased him all the way to his house and now the police are waiting on the street for him. Man after putting this vararam on my Yukon Denali it really really moves out now. Just thinking it was a really dumb move for me to do this in my daily driver. This guy is like five streets down from me. Should've went in my trans am