Testing 4WD Actuator/Disconnect?

[coh998]

I've just replaced the oil pan and most of the front drivetrain & suspension on an '03 TrailBlazer that had been sitting for years. 4WD functional status was unknown by me before the repair. Don't know if "Service 4WD" light was on before, but it is now.
I used a budget Intermediate Shaft Bearing Housing/4WD Actuator set. Long story short, it doesn't make any noise when I select AWD, 4Hi, or 4Lo. I can hear the Transfer Case Selector Motor sometimes, but only when selecting in or out of 4Lo.
I am wanting to test this cheap-ass Actuator. I tried removing it from the housing and leaving the cable attached, but hitting the 4WD Selector Switch does nothing in any position. Could be a bad Actuator or a bad signal. I have the old one still, and it, too, does nothing when unbolted. Is there an easy test procedure to prove this Actuator *might* work if it gets a valid signal from all controllers?

 

[Mooseman]

You would need to scan for the code that the TCCM is having. An ELM327 bluetooth adapter and the Car Gauge Pro app on Android would be able to do that, unless you already have an advanced scanner capable of scanning these codes.

I'm not sure if the disconnect's actuator can be tested. Looking at the schematics, there are 4 wires going into it. Not sure how the TCCM controls it.

 

[coh998]

I just tried the VXDiag VCX Nano for all diagnostics and programming, but it was having "communication failures". Not sure if it was software issues (I never saw a more confusing set of instructions), or maybe it's just not *fully* compatible with all GM Diagnostic System Checks ("Class 2 Devices"). I got sick of messing with that pile of confusion, so it's on it way back for a full refund. Am currently looking for a fully compatible MDI clone that doesn't require Win7 to run Tech2Win... I do have an ancient "ELMScan 5 Compact," but I'm on iOS, so in the meantime, maybe I can find an app that can see the TCCM codes. I didn't know there were any that could! Thanks for the schematics!

 

[mrrsm]

FWIW... This suggestion may turn out to be a mere Ricochet while trying to Hit the Bullseye of your Problem Target... But I suspect that by viewing this Video from Eric "O" at South Main Auto using a Tech 2, as he identifies the Specific Trouble CXXXX Code and by observing his Diagnostic Procedures he follows here... they might provide some insight as to what you need to do to rectify this issue on your GMT360 SUV:

Don't get Hung Up over the fact that he was investigating this issue on a GMT800... Just follow along with the steps he takes to get the 'Gist' of this approach:

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[coh998]

FWIW... This suggestion may turn out to be a mere Ricochet while trying to Hit the Bullseye of your Problem Target... But I suspect that by viewing this Video from Eric "O" at South Main Auto using a Tech 2 [...]

I like South Main Auto Repair LLC's YouTube stuff. In addition to my 4WD issues, I've got a parasitic voltage drain killing the battery overnight, and I was just watching his advice on finding one of those. I also saw some of his stuff when I was doing the oil pan & Intermediate Shaft, etc,... too. He does nice work.

Funny you should link to this video. Way back when I started this project and was trying to get it out of the weeds where it sat for years, to get it to move the first thing I needed to fix was a huge mouse nest by the fuse box with 3 wires chewed through. I soldered mine. ;-)

I'm starting to worry that some of this in-depth troubleshooting might be over my head. There seems to be a lot of arcane knowledge taken for granted that no one ever explains, like "We'll just treat this 3-wire connector like usual, ..." Umm, hello?! What does that mean, exactly? Lol! Even if I do get the MDI and an SPS subscription, I'm afraid I still won't understand how to use it properly.

Do you know of a good book or GM training material on reading schematics with real world info on troubleshooting logic and best practices?

 

[mrrsm]

Admittedly... At first blush... Such 'Mechanical Diagnostic Jargon' might seem to be A Bit "Smug" ...until you realize that all of us MUST "Hit The Books" from time to time and get a Good Foundation to work from if we want to "Skip that $500 -$750 Dealership Charge" for whatever they put their hands upon ...and REALLY try to figure things out for ourselves.

The resources are certainly there; some obvious, like YouTubes by the Score ...and some that require just a little bit more digging to *Winkle* them out of Hiding. Take for example that "Implied Hidden Knowledge" reference made by Eric "O" as to what always needs to be investigated about a "Three Wire Connector". THIS Article is about "Understanding what 5 Volt Reference Voltage Means" and is a great place to start:

Troubleshooting 5V Reference Circuits - Clore Automotive

In modern vehicle design, 5-volt reference signals/circuits are a key aspect of vehicle command and control. As summarized by Gary Goms, the 5-volt reference

cloreautomotive.com

As for what Eric "O" managed to accomplish in that Video, just consider that he did NOT allow himself to get overwhelmed and left out in the Tall Weeds with a Typical Diagnostic Flow Chart or by using High End Tools or his $4,000 Scanners to figure things out that Two Other Dealerships and One Other "Pro-Shop" FAILED to do.

Rather, HE WENT BACK TO BASICS AND USED HIS COMMON SENSE. Even as SICK as he was on that Day with the Flu-Sinus Infection and Dizziness... He cut to the chase by Using One Jumper Wire, A Probe Light, his DMM and a Flash-Light after taking ONE BIG STEP BACK to REALLY see the possibilities causing failures more realistically.

In the end.. .it came down to One Single Damaged 5 Volt Reference Wire... that had NOTHING to do with getting discovered by using the High End Scanners and Scopes he could have tried using instead.

The 'Sun Tzu Mechanic's Lesson' from this Event is Clear:

ALWAYS Start any Electrical Problem Diagnostics using EXAMINING WIRING DIAGRAMS and just Trace Out One Wire At A Time. Don't allow the Failures of Imagination in Others to get between YOU and the SOLUTIONS to such Diagnostic Problems.

Begin with Powers and Grounds and Check for their Basic Electrical Continuity between the Wiring and The Connector(s) in The Circuit. Use the Diagrams to NARROW THINGS DOWN.

As with this example where Eric "O" Zoned In on that ONE Broken, Brown & White WIRE. In your situation, perhaps all your are looking for is that One Wire in between the TCCM and the Dash Board Switch that presents with an "OL" (on the Ohms Setting) on your DMM as "Out Of Limits" or shows up as an Open Circuit because somewhere in between... there is either a Broken, Corroded ...or like THIS Case... A Wire that has been Chewed Through.

Follow Along below with The Paul, James & Caleb "Scanner" Danner Family of Troubleshooters...and JUST WATCH HOW THIS PROCESS WORKS!!!

 

[coh998]

[...] Take for example that "Implied Hidden Knowledge" reference made by Eric "O" as to what always needs to be investigated about a "Three Wire Connector". THIS Article is about "Understanding what 5 Volt Reference Voltage Means" and is a great place to start:

Troubleshooting 5V Reference Circuits - Clore Automotive

In modern vehicle design, 5-volt reference signals/circuits are a key aspect of vehicle command and control. As summarized by Gary Goms, the 5-volt reference

cloreautomotive.com

Thank you! That's exactly the kind of 'how to think logically about electrical troubleshooting' I need. If we take a step back and 'increase the range of measurement,' so to speak, I can give you a wider idea of what I'm up against:

• This '03 TrailBlazer had been hit by lightning. Repair was covered by insurance, but my daughter cannot find the service records, so I don't know what was diagnosed, repaired, replaced or reprogramed.
• After returning to use, the transmission failed and was replaced. Again, no service records are available.
• 4WD allegedly worked until attempted engagement resulted in loud 'bang'. Visual inspection discovered serious oil pan leak. Vehicle was not repaired and parked for years until divorce necessitated its revival by me. Husband (now ex-,) has tenuous relationship with Truth. He maintains that loud bang *caused* oil pan leak; I believe massive shock to right front axle transferred through suspension/drivetrain into I-Shaft Bearing Housing and broke oil pan. Whatever...
• While rebuilding front suspension and drivetrain, I discovered apparently new A/C Compressor installed but not attached to any electrical wire or refrigerant hose. Daughter knew nothing of this. Ex spews utter nonsense when asked why new compressor installed but not hooked up and wife not informed. Whatever...
• After I repaired the wire harness and got it started, daughter says mileage reading is *way* off; tens of thousands of miles too low. ECU immediately suspect. She assures me reading was correct long after lightning strike repair...
• I've tried an ancient (by today's standards, not '03 standards) ELMScan 5 Compact OBD-II reader running currently discontinued OBDwiz app from ScanTools. It says "No Codes Present."
• Tried VXDiag VCX Nano Tech2 emulator but massively confusing and conflicting instructions caused me to send that pile of nonsense back. I got some info out of it about modules being present - not responding, but I can't trust any of it. Currently looking for an MDI emulator with better instructions. I do have the $40 VIN registered in Techline Connect, so I got that goin' for me, which is nice... ;-)

There's not many miles on it since I put it back on the road. It's running fine and she's as happy as a clam to be mobile again. I'm hoping some error codes will re-establish themselves to give me some clues on where to start, but since there is a parasitic drain on the battery and she is disconnecting it every night, I'm guessing that whatever codes are appearing are getting lost with every disconnect...? Oy, yoy, yoy! Am I having fun yet?!

Anyway, thanks for your help, fellas. Writing this stuff out helps me to get it straight in my head, at least. I'm on my way over there—oh, yeah, I forgot to tell you this thing is 20 miles from my house. It's a 40-mile round trip every time I want to work on it. Today I'm going to try (again) to pin down the parasitic drain...

 

[Mooseman]

For the mileage, I can tell you that it's stored in the cluster, not the ECU. Things that are stored are VIN, Oil life monitor % and Transmission adapts. It also keeps throttle body adjustments to keep up with how dirty it gets but is reset whenever the battery is disconnected.

Before we get off into the weeds with all the other stuff, lets stay with the 4x4 system. You need to get the codes when the service 4x4 light is on. Without that, we're just shooting in the dark.

 

[mrrsm]

...Or... If you think that the Battery Drain Down is the more immediate issue for your Daughter...

Eric "O" From South Main Auto has an interesting Repair Video (involving a 2003 Trailblazer) where he demonstrates the procedures for Running Down a Hard To Find Low Amperage Drain in a Trailblazer that he suspects will end up being caused by a Non-OEM Instrument Cluster Panel (IPC)

In some OTHER Parasitic Drain Videos involving a Different GM-GMC Truck... Eric "O" speaks on the SMA Shop Phone with a TRUE IPC Repair Specialist who explains that the IPCs WILL short out if prior repair Soldering was done with a NON-LEAD Solder, allowing the growth of Weird Metallic Crystals to literally propagate and "crawl across the Logic Board"... Making Electrical Contact and Shorting with the "Always HOT B+ Positive areas of the IPC Green Board...and thus... The Perpetual Battery Drain continues:

If nothing else, it follows on that Eric "O"s Diagnostic Strategies should be added to your list of 'Automotive Repair BFFs'. His methods and his manners of Teaching are precisely what you want to see as often as possible in EVERY imaginable Automotive Repair problem. More than likely.. .Eric "O" has "Been THERE... Done THAT...and GOT The "T" Shirt..." You will also come to appreciate the presence of Mrs. "O" and their Family in those Videos as well.

Here is another Video (I'm unfamiliar with this Fellow) that is On Topic and might also HELP as it involves a Broken Seat Carriage cutting into and Shorting Out a Wire Bundle:

Prepare yourself (and any Young Kids within Earshot) for some "Coarse Language" ever punctuating Drew's Videos... BUT... His information is invariably PROFESSIONAL and worth watching and learning from:

In this first case, the Parasitic Draw in his own "Minty Green Trailblazer" was in the Ignition Switch Circuit:

Part 1:

In this second issue... the IPC stays ON during a Parasitic Drain:
Part 2:

 

[coh998]

[...] Before we get off into the weeds with all the other stuff, lets stay with the 4x4 system. You need to get the codes when the service 4x4 light is on. Without that, we're just shooting in the dark.

Okay, thanks. Let's start there with a very simple question - what device and/or software do I need to read *all* possible codes from *all* modules in this '03 TrailBlazer?

I have a Macbook that can run any version of Windows; I own copies of Win 7 & Win 10. I use iOS smartphones and tablets, not Android. My understanding is that ELMScan 327 and other OBD-II Bluetooth and USB devices cannot read all GM modules and codes. Is this true?

Am currently scraping up enough $$ and researching to buy an MDI clone for use with Tech2Win and Techline Connect. Is this the preferred way to go to access all factory codes and diagnostics? Is it do-able and fully compatible without costing a ridiculous, intentionally prohibitive amount of money?

I tried a different J2534 passthru device and wound up with a big, steaming pile of Chinese dog doo. It was reasonably priced, but didn't work. ;-) Can you recommend a reputable MDI clone device that can use Tech2Win and Techline Connect without requiring a multi-lingual software engineer to setup, configure, and use?

 

[mrrsm]

I like Dr. Shock's Presentation Videos for both his GM Tech 2 Clone and for his GM MDI Clone:

**** Click on the "Show More" option here to get More Data and suggestions:

Here he explains the GM MDI SPS PASS-THRU PCM Re-Calibration Procedures:

Then continue by checking out THIS eBay Offer and look further down on this same page for more similar offers that specify the PASS-THRU, GDI and MDI Features that WILL allow SPS Programming via TIS2WEB and TIS2000, etc.

Many of these GM MDI Clones look like the same thing at a Much Cheaper Price than the BOSCH OEM UNIT ...but THAT may be the BEST reason to PASS on most of them. The OTHER Red Flag is any Vendor with a LESS than 100% Sales Rating... or any having MINIMAL Numbers of Sales:

Multiple Diagnostic Interface for GM MDI1 Interface Scanner Tool Best Quality | eBay

Find many great new & used options and get the best deals for Multiple Diagnostic Interface for GM MDI1 Interface Scanner Tool Best Quality at the best online prices at eBay! Free shipping for many products!

www.ebay.com

And along the same lines...from AliExpress:

Gm Mdi Scanner - Automobiles, Parts & Accessories - AliExpress

Buy gm mdi scanner at a great price. This part is a new gm mdi scanner. Also shop for automobiles, parts & accessories at best prices on AliExpress!

www.aliexpress.com

 

[coh998]

...Or... If you think that the Battery Drain Down is the more immediate issue for your Daughter...

[...]

Yes, I've seen all these videos. They're all excellent! Thanks for the links. Of course I searched YouTube before I came in here asking questions.
I've got a steady 90 mA draw, if I'm reading my Ryobi multimeter corectly. The range selector confuses me on this thing. I never really liked this meter, the LCD screen is difficult to make out unless you're looking at the exact right angle, and the contimuity beeper is impossible to hear unless your ear is right up against it. I just bought a new Kaiweets multimeter in an effort to get something I trust better, but it turned out to be defective! Reads Volts fine, but I get 0.000 on all Amp or milliamp readings. Yes, the leads are attached correctly. It figures I'd buy a defective meter for this job.

So I have a 90 mA parasitic draw, I think. But after pulling every fuse and relay in both fuse boxes, I can't make it go away. Certain fuses, when re-installed will wake something up that pulls 1.2 A, but it goes away in a few seconds and the reading returns to 90 mA. So now I'm thinking that since it doesn't appear to be on a fused circuit, it might be the alternator with a failed diode. Gonna' go check that next trip over there...

Thanks for playin' along...

 

[mrrsm]

NP... Not to make you Paranoid.... But is there any chance that your "Ex" has perhaps installed something *hidden* inside of the vehicle to try and Remotely Monitor, Track and/or Record your Private Movements, Actions or Conversations?

Just saying...

And if it has a more mundane cause & origin... Does this SUV have any After-Market Alarm System or an Up-Graded or After-Market Radio installed? If so, try to un-plug the Radio Harness and see if that 90 mA Draw subsides.

On occasion... an intrepid Youngster will attempt to "Play The Slots" in the CD Player in the Dash by Dropping Coins, Bobbie Pins or Paper Clips inside the Platter Insert Point and accidentally connect the "Hot At All Times" Power from an internal Circuit Board to Ground.


"I Have Known It Done..." Poo-Bah from G&S "The Mikado"

 

[coh998]

NP... Not to make you Paranoid.... But is there any chance that your "Ex" has perhaps installed something *hidden* inside of the vehicle to try and Remotely Monitor, Track and/or Record your Private Movements, Actions or Conversations?

Just saying...

And if it has a more mundane cause & origin... Does this SUV have any After-Market Alarm System or an Up-Graded or After-Market Radio installed? If so, try to un-plug the Radio Harness and see if that 90 mA Draw subsides.

On occasion... an intrepid Youngster will attempt to "Play The Slots" in the CD Player in the Dash by Dropping Coins, Bobbie Pins or Paper Clips inside the Platter Insert Point and accidentally connect the "Hot At All Times" Power from an internal Circuit Board to Ground.


"I Have Known It Done..." Poo-Bah from G&S "The Mikado"

I don't think there are any nefarious gizmos installed. It sat for years and came out of the weeds this way. Stock radio, and no fuse makes any difference in draw. There's an electric trailer brake bolted under the dash with wires snaking through a gap. If alternator proves okay, I'll pull that under-dash panel and see where those wires go. Can't imagine they're not fused, but there's only one way to find out...

 

[Mooseman]

Okay, thanks. Let's start there with a very simple question - what device and/or software do I need to read *all* possible codes from *all* modules in this '03 TrailBlazer?

I have a Macbook that can run any version of Windows; I own copies of Win 7 & Win 10. I use iOS smartphones and tablets, not Android. My understanding is that ELMScan 327 and other OBD-II Bluetooth and USB devices cannot read all GM modules and codes. Is this true?

iOS was always a PITA to get anything to work. Android was always ahead there. There might be one but it's not explained what it can do:

OBD Fusion + Bluetooth Scanner = Pretty Neat!

I picked up a $35 bluetooth scanner on amazon, and I bought the $10 ODB Fusion app on the iOS app store. It's pretty cool. I like how I can make my own little mini dashboards. I've been playing around with all the PIDs. Many work, like speed, instant fuel-economy, throttle position etc. Many did...

gmtnation.com

According to this thread, there is an iOS app however, it only natively scans the PCM. It has a terminal in it however no indication of how to send the command to get TCCM codes out.

SOLVED! - Can't Scan for ABS Code

My 4.2 Buick has been throwing up a random ABS/Brake light CHECK BRAKE SYSTEM warning for the last two months. After trying a couple easy fixes, I realized I needed to scan for the code. My cheap OBD2 scanner wouldn't do ABS "C" codes, so I bought an ELM327 reader and used iOS phone apps. None...

gmtnation.com

There is the VCX Nano that works with Windows however a few have tried it and the software is flaky at best, if you can get it to work at all.

You can read through the whole scan tool section if you can find something.

Scan Tools

OTC, Innova, ScanGauge, Bluetooth and WiFi readers included. This will also cover Apps such as Torque, DashCommand and PC based Diagnostics software. Share your experience with the tools. No code diagnostics to be done.

gmtnation.com

And lets stay on topic of the TCCMé4x4 issues. A separate thread for other issues should be started.

 

[azswiss]

According to this thread, there is an iOS app however, it only natively scans the PCM. It has a terminal in it however no indication of how to send the command to get TCCM codes out

If you can get a serial terminal working then we can get you the command sequences to interrogate the TCCM (as well as any other module!). Feel free to message me for details.

 

[budwich]

not sure if any of these help but you should be able to see some of the signals at the actuator connector with a simple test light or meter. Have you tried that?

 

[coh998]

not sure if any of these help but you should be able to see some of the signals at the actuator connector with a simple test light or meter. Have you tried that?

Man, these .pdf's are awesome! Thank you! I had been paying the $20 for 3 Days' access to ACDelco TDS during the front end rebuild. I'm up to $80 so far in there, but I hadn't ponied up yet another $20 for the TCCM troubleshoot yet. Thanks to mrrsm, and his links to Eric O's South Main Auto channel on parasitic drain up above, I went deeper on his channel and learned about other subscriptions to factory data: AllData DIY, Mitchell1, Identifix. I haven't made a decision there yet, pending further research on MDI clones and availability of funds to buy/subscribe...

The entire project is in limbo at the moment. The TrailBlazer in question is in service and is not available to me for further troubleshooting on the parasitic drain & TCCM issues because she has sold the house and has until next Saturday to get out. It seems to be running fine as a moving van, but for one P0420 code from the catalytic converter on a really hot day that I cleared and has not yet returned...

I've learned a great deal in here and am deeply grateful for all the help, though I do apologize for all the non-actuator/disconnect-related chatter in this thread. When things settle down after next weekend (hopefully), I'll get back to it and report back here, with new threads for parasitic drain testing and factory service data methods, etc,...

Again, many, many thanks!

 

[budwich]

I believe that you can find "dvd like" service manuals on ebay for about $20. I haven't looked in a while since I bought mine years ago. Anyway, good luck with your fight, hopefully you will get to the bottom of both. A real hot cat doesn't sound good. I am thinking there is a fueling issue somewhere.

Also note that a form of the gm service manual can be down loaded from the links on mooseman's signature in his posts.

 

[coh998]

I believe that you can find "dvd like" service manuals on ebay for about $20. I haven't looked in a while since I bought mine years ago. Anyway, good luck with your fight, hopefully you will get to the bottom of both. A real hot cat doesn't sound good. I am thinking there is a fueling issue somewhere.

Also note that a form of the gm service manual can be down loaded from the links on mooseman's signature in his posts.

Yes, I've seen those $20 DVD's on eBay, and I may be wrong, but I'm convinced they're nowhere near complete factory service manuals. You say you bought one years ago? Is it actually a full and complete *accurate* copy of the *actual* GM factory service manual for that year's TrailBlazer, Envoy, etc,...? I haven't been able to find any review of those discs or their contents and don't feel like wasting $20 on something that isn't exactly what I demand. What I'm looking for is worth way more than $20, and rightfully so, so I'm pretty sure that's not it.
Mooseman's library of .pdfs is quite useful for lots of general info, but again, not a complete set of service manuals with fully organized Table of Contents and all troubleshooting and repair procedures. I discovered them when I first went looking for how to R&R the Oil Pan and grabbed 'em up with high hopes! GM Manuals for free?! Awesome! Well, there's a nice diagram of the Oil Pan in there, but no step-by-step procedure on how to get the daggone thing outta' there. It sure as hell isn't:

Step 1. Remove the bolts. Step 2. Drop the Pan. (That's the procedure this old dawg is used to.)

So I paid $20 to AC Delco TDS for 3 Day's access to The Factory Service Manual and downloaded the *41* sub-assembly .pdf's linked to in that step-by-step "Oil Pan - Replace" procedure, and I was happy to pay it! But money's tight, so I haven't pulled the trigger on that printed copy of the Genuine GM, gently used (No Pages Missing!) 3-book set available on eBay for @$200. I'm savin' my pennies...

But again, as I said I'm very grateful for the info in this thread, because it led me to Eric O's South Main Auto YouTube channel. In there he's got a vid on factory service data and where he gets it online that let me know I could have had *30 days* access to the factory info for the same $20 I gave AC Delco for only 3 days access! With extra info on how other subscribers have dealt with whatever procedure you're working on! Access to pro advice like that might be worth the $20 all by itself! So even after I do scrape up the $200 for the Genuine manuals, I'm pretty sure I'll add another $20 to get access to those extra resources when I need it, too!

Apologies again, Mooseman, for the off topic rants. I'll try to get it together, I promise. ;-)

 

[mrrsm]

Whoa... Dude... Take A DEEEP Breath... Then Grab a Cold One... and after you put your feet up... Sit back for around Two Hours and Watch ALL of the Procedures THIS Dude has Video Documented in "How to Perform the Timing Chain R&R on the GM 4.2L Engine" which includes each and every step for "How to R&R the Crankcase-Oil-Pan on the GM 4.2L Engine"...Too: :>)

"Slow Down... Frankie, My Son..."
Doug The Head to Frankie "Four-Fingers" from the Movie "Snatch"

 

[budwich]

Is it actually a full and complete *accurate* copy of the *actual* GM factory service manual for that year's TrailBlazer, Envoy, etc,...

The ones that I got are "complete" service manuals. They were actually on a DVD (2) because they couldn't fit all the stuff that was therein. Further, its covers 2002-2009 and all trucks in the GM line.... quite exhaustive. Your question about exactly what's in them... I have only looked at things that I need (and to some extent, that others on the forum need).... and never actually seen a GM SM in the flesh... maybe back in 75... three volumes, hard copy. Based on my limited looking at mooseman's collection, I would say it is at least as "complete" as those. The one main difference, is that the system that was included also has searching capabilities across all the documents for that year / model.
Anyway, it doesn't really matter as long as you get the info that you need which is likely to come from the forum herein.

 

[coh998]

Whoa... Dude... Take DEEEP Breath... Then Grab a Cold One... and after you put your feet up... Sit back for around Two Hours and Watch ALL of the Procedures THIS Dude has Video Documented in "How to Perform the Timing Chain R&R on the GM 4.2L Engine" which include each and every step for "How to R&R the Crankcase-Oil-Pan on the GM 4.2L Engine":

I saw it! I have that one bookmarked. I think I've seen every YouTube that even mentions the TB Oil Pan, Intermediate Shaft Bearing Housing, 4WD Disconnect/Actuator, Transmission Flush, Power Steering Flush, etc,...

I used to work on military commsats, so for me it's *all* about the printed specs& drawings.