No Crank electrical issue

[hypnoseternity]

After reading several threads on the symptoms leading up to my no crank issue, I have only pointed the finger in even more directions than I started trying to diagnose my problem.

First, 05 trailblazer LS 4.2 4wd

Now, the list of symptoms.
-first was an issue with the lift gate after grounding out a power cable for a stereo amplifier to the body. Lift gate immediately repeatedly tried to lock when open but would unlock and lock with driver door control, and in gear safety switch. The rear wiper was noticed inoperable 2 days later. Was able to unplug and plug back in and restore function to the wiper, but only until lock actuator was used, and then I would have to start that process over again. Driveable, so down the priority list.
-a week or 2 went by driving it that way, and then the problem I've read about over and over on here happened. While driving, all dash lights came on. No bumps, no wetness, no change in straightline 45 mph smooth sailing to preceded the problem, it just happened. Less than 5 minutes later, it seemed like an attempted reset. Some dash lights went out, and locks locked and then unlocked. Continued total driveability. At stop but before power off, noticed that fuel, oil psi, temp, and volt gauges were dead. No gear indicator. The airbag, pbrake, abs, battery, and cel were all lit. Power was gone to front windows (leaving mine slightly open), front locks, no door instrument control, radio, and 4wd switch indicator. Turned it off, and then back on, no change. Still started and drove fine, tach and speedo still good. This went on another week before I tried replacing the megafuse.
-after disconnecting the battery and installing the new mega fuse, I was left with all of the previous problems, plus no crank. I have tried so many of the tricks I've read on here.

This is what all I've done...
-reinstalled previous megafuse that was apparently not faulty to begin with.
-new battery
-new starter relay
-new ignition (which isn't triggering the security light, but since I can't trust my cluster, I performed a relearn anyway to no avail)
-pulled cluster. Opened it up and cleaned all the tiny solder points I saw with qtips and rubbing alcohol. (Note that the protective clear coating had bubbled and turned to dust upon my cleaning, but no noticible dark spots anywhere on the board.)
-pulled, cleaned, and reseatted the ground on the bottom passenger side of center console (g102?) And the one to the frame near battery, and also the one to the engine block. (I'm betting there are others that I just didn't see in what schematics I've looked at)
-Did a wiggle check of every single harness and black box I could find under the dash and under the hood to no avail.
-disconnected amplifier completely, but left aftermarket stereo because all chime function is now routed through it. (But no power to it anyway for now)
-checked every single fuse in the front and rear fuse blocks. (Only bad one was for cigar lighter)
-properly pulled giant pcm plugs, cleaned, lubed, reseated.
-tried a trick for resetting the pcm (pulling 2 fuses and letting it sit for an hour)
-checked for broken wires coming out of the blue pcm plug all the way to the splice attached to the battery looking for (open in circuit 440 issue)

I can say that I can jump the starter relay slots with key to on and get it to turn over and fire up, but it immediately dies. So, no fuel, or fuel shutoff somehow or another. (Maybe still passlock?) And the starter relay is definitely not getting the switch signal.

I have made ZERO progress so far.

There are still lots of things to try, I'm sure, and I read through and tried as much as I've been able to in the past few days. But I'm ready to ask for help. What do I try next?

 

[hypnoseternity]

Also! My crappy code reader can't communicate with the truck, so no go as far as that, but its not a nice expensive one either.

 

[Maverick6587]

Welcome to GMT!

Does the code reader turn on (getting power)? If not then you probably blew fuse 13 (I think) under the hood. That fuse powers the cig lighters and the OBD2 port.

Have you checked all your fuses with a multimeter (all of them, even the ones under the back seat)?

I would suspect that you blew a fuse or "injured" the BCM. Having code or two would greatly help narrow down where the problem is though.

 

[hypnoseternity]

Welcome to GMT!

Does the code reader turn on (getting power)? If not then you probably blew fuse 13 (I think) under the hood. That fuse powers the cig lighters and the OBD2 port.

Have you checked all your fuses with a multimeter (all of them, even the ones under the back seat)?

I would suspect that you blew a fuse or "injured" the BCM. Having code or two would greatly help narrow down where the problem is though.

I have checked all fuses, yes. I did have one blown for the cigarette lighter, but it did not restore diagnostics port. Or this code reader might actually suck that bad. Ha! But it did read a 2013 Yaris. This code reader simply tells me it can't communicate.

 

[Maverick6587]

What did you lube the pcm plugs with?
What model code reader are you using?

 

[NJTB]

If I remember correctly, there's a fuse in the rear box under the seat for the cigarette lighters, too.

 

[mrrsm]

After reading your Symptoms List a few times... focusing on the problem of the Wires and Harness of the LGM (Lift gate Module )... THE Place to "Start" seems to be with examining the Class 2 Network inside of your Vehicle. Briefly, the communications flow from and to the PCM and the BCM uses a Single Wire Network Topology in which all of the Modules (...including the PCM. the BCM and the Lift Gate Module) get there Inputs and Outputs by varying the Pulse Width between 0 and 7 Volts.

These High to Low states act like "Morse Code" for the PCM and BCM to listen to, interpret and respond back and forth with ALL of these Modules residing on a Single Wire for the Pulse Width Modulation to occur. The Class 2 Databus uses (2) Central Collection Points called "Splice Packs" or "Combs" at two Primary Junctions; One being under the Dashboard on the Driver's Side of the SUV and the Other located under the Right Rear Passenger Seat. It is very important to understand that if ANY One Module goes down by either Shorting to Ground or Shorting to 12 Volts DC... the ENTIRE Class 2 Network can be affected and brought down.

I know this might seem a bit overwhelming at first... but THIS Video...once downloaded and played at 1/2 Speed a few times over the Critical Views of this Instructional will show you how to "Take Down The Databus" by removing the Comb Connectors...and then gradually adding in each individual Module Wire Connector until you can Isolate Which Module is the Problem Child.

It would be nice for you to have an inexpensive Hantek Oscilloscope and a Laptop along with a "GYMKO" Tech 2 Clone to view the PWM Pulses being investigated and also to Check Each Module for its "Active - In-Active" Status. (Check out the Hantek Youtube Videos) ... but you can STILL perform THIS Investigative Repair with just a Few Basic Tools:

(1) A DVOM (Digital Volt Ohm Meter)
(2) A Lighted "Pin Probe" to check for Powers and Grounds
(3) A Bright Flashlight
(4) A Small Paper Clip, Safety Pin or a Piece of Safety Wire for Comb Probes and Connectors

Please Download, Save and Watch this Video as many times as necessary and you'll discover whether all of these Electrical Problems have their Cause and Origin on the GM Class 2 Network Databus. Good Luck :>)

 

[hypnoseternity]

After reading your Symptoms List a few times... focusing on the problem of the Wires and Harness of the LGM (Lift gate Module )... THE Place to "Start" seems to be with examining the Class 2 Network inside of your Vehicle. Briefly, the communications flow from and to the PCM and the BCM uses a Single Wire Network Topology in which all of the Modules (...including the PCM. the BCM and the Lift Gate Module) get there Inputs and Outputs by varying the Pulse Width between 0 and 7 Volts.

These High to Low states act like "Morse Code" for the PCM and BCM to listen to, interpret and respond back and forth with ALL of these Modules residing on a Single Wire for the Pulse Width Modulation to occur. The Class 2 Databus uses (2) Central Collection Points called "Splice Packs" or "Combs" at two Primary Junctions; One being under the Dashboard on the Driver's Side of the SUV and the Other located under the Right Rear Passenger Seat. It is very important to understand that if ANY One Module goes down by either Shorting to Ground or Shorting to 12 Volts DC... the ENTIRE Class 2 Network can be affected and brought down.

I know this might seem a bit overwhelming at first... but THIS Video...once downloaded and played at 1/2 Speed a few times over the Critical Views of this Instructional will show you how to "Take Down The Databus" by removing the Comb Connectors...and then gradually adding in each individual Module Wire Connector until you can Isolate Which Module is the Problem Child.

It would be nice for you to have an inexpensive Hantek Oscilloscope and a Laptop along with a "GYMKO" Tech 2 Clone to view the Pulses being investigated and also to Check Each Module for its "Active - In-Active" Status. (Check out the Hantek Youtube Videos) ... but you can STILL perform THIS Investigative Repair with just a Few Basic Tools:

(1) A DVOM (Digital Volt Ohm Meter)
(2) A Lighted "Pin Probe" to check for Powers and Grounds
(3) A Bright Flashlight
(4) A Small Paper Clip, Baby Pin or a Piece of Safety Wire fro Comb Probes and Connectors

Please Download, Save and Watch this Video as many times as necessary and you'll discover whether all of these Electrical Problems have their Cause and Origin on the GM Class 2 Network Databus. Good Luck:

Not anymore overwhelming than what I've already attempted. Give me some time with this one, and I'll report back. This is the kind of troubleshooting info I think I needed. Thank you SO much! I'll report back as soon as I have a chance to dig in to this mess like you've suggested.

 

[mrrsm]

Welcome to GMT Nation... Brother!

 

[hypnoseternity]

After reading your Symptoms List a few times... focusing on the problem of the Wires and Harness of the LGM (Lift gate Module )... THE Place to "Start" seems to be with examining the Class 2 Network inside of your Vehicle. Briefly, the communications flow from and to the PCM and the BCM uses a Single Wire Network Topology in which all of the Modules (...including the PCM. the BCM and the Lift Gate Module) get there Inputs and Outputs by varying the Pulse Width between 0 and 7 Volts.

These High to Low states act like "Morse Code" for the PCM and BCM to listen to, interpret and respond back and forth with ALL of these Modules residing on a Single Wire for the Pulse Width Modulation to occur. The Class 2 Databus uses (2) Central Collection Points called "Splice Packs" or "Combs" at two Primary Junctions; One being under the Dashboard on the Driver's Side of the SUV and the Other located under the Right Rear Passenger Seat. It is very important to understand that if ANY One Module goes down by either Shorting to Ground or Shorting to 12 Volts DC... the ENTIRE Class 2 Network can be affected and brought down.

I know this might seem a bit overwhelming at first... but THIS Video...once downloaded and played at 1/2 Speed a few times over the Critical Views of this Instructional will show you how to "Take Down The Databus" by removing the Comb Connectors...and then gradually adding in each individual Module Wire Connector until you can Isolate Which Module is the Problem Child.

It would be nice for you to have an inexpensive Hantek Oscilloscope and a Laptop along with a "GYMKO" Tech 2 Clone to view the PWM Pulses being investigated and also to Check Each Module for its "Active - In-Active" Status. (Check out the Hantek Youtube Videos) ... but you can STILL perform THIS Investigative Repair with just a Few Basic Tools:

(1) A DVOM (Digital Volt Ohm Meter)
(2) A Lighted "Pin Probe" to check for Powers and Grounds
(3) A Bright Flashlight
(4) A Small Paper Clip, Safety Pin or a Piece of Safety Wire for Comb Probes and Connectors

Please Download, Save and Watch this Video as many times as necessary and you'll discover whether all of these Electrical Problems have their Cause and Origin on the GM Class 2 Network Databus. Good Luck :>)

On a whim, I went to a local junkyard and found a bcm in an identical trailblazer. Same color codes on it. Both had red code, and even identical trim colors. Swapped it with mine, and brought back my 4 dead gauges on the instrument cluster. No security light at all, which was surprising, but an awesome surprise. Still have the 4 indicator lights, fueo shutoff, and no signal to starter relay.
Now, to get to work with a test light and probe to see what else I can pin down as faulty.
This was an excellent video! Thank you so much for sharing it!

 

[mrrsm]

Very glad for your progress. What would be particularly helpful now...is a Tech2 -> TIS2000 SPS Calibration Update for your PCM-BCM configuration and see if the Module Software Updates add to the remedies you seek. Have you queried the "Calling ALL Tech 2 Owners" Thread for anyone close enough to you that might respond for a nominal fee and do this re-calibration? At this point... it certainly wouldn't hurt to ask. :>)