Fuel pump

[Road Trip]

Can you edit that picture to full size, when I click on picture it’s still unreadable. Thanks

Yeah, I also noticed after the fact that a full screen snap is sub-optimal when wiring diagrams are involved.

Let's try this instead. Instead of a screen snap to a .jpg, this time I extracted the page in question to
a .pdf file and attached that. On my end this looks to be a near 100% improvement in wiring diagram readability?

Let me know what it looks like on your end.

 

[Caman96]

Yeah, I noticed after the fact that a full screen snap is sub-optimal when wiring diagrams are involved.

Let's try this instead. Instead of a screen snap to a .jpg, this time I extracted the page in question to
a .pdf file and attached that. On my end this looks to be a near 100% improvement in wiring diagram readability?

Let me know what it looks like on your end.

1000% better, thank you!

 

[Road Trip]

OK, I put in a carquest pump as I was stranded. It works, the truck runs, I'm happy.
I guess nobody has any idea of why the gauge jumps when I foot the brake pedal. Hunh?

Clean your grounds at the tank, the rear taillights, and under the dash.

Hello 62barsoom,

ETA's advice above is proven good. Sounds crazy, but isn't. As a matter of fact,
what the '97 FSM has to say about Instrument Cluster diagnosis adds credence to this
train of thought:

You must be registered for see images attach

Strange but true -- the analog GMT400 instrument cluster can be adversely affected by at least 3 different grounds. (Some might add unpredictably / incomprehensibly. :0)

Simply put, make sure and verify all the grounds that ETA and the FSM recommend...and your gas gauge should no longer be affected by your foot on the
brake pedal...

****

(Optional reading)

Even so, I wasn't happy about the fact that I can't take a piece of paper and draw you a simplified circuit of a
specific marginal ground allowing 'crosstalk' between the brake pedal and the gas gauge. I even slept on it...
and it still bugs me. :0) So even if I have yet to figure out where the 2 electrical circuits intersect, I can at least
show you the Power, Ground, and fuel quantity signal wire that the gas gauge is supported by. Here's page 1 of 2:

(from the '97 FSM, colored to help continuity across pages)

You must be registered for see images attach

Nothing earth-shattering here. Unfortunately, this '97 wiring diagram is drawn the old way, where you
have to go off-page to see the power & grounding. So here's p. 2 of 2:

You must be registered for see images attach

So, at the end of the gas gauge rainbow we discover that one of the engine grounds is used: G103.
Keep this in the back of your mind as you view the page covering the fuel pump / fuel sending unit:

You must be registered for see images attach

How about that? Not only is the fuel gauge in the Instrument Cluster relying on G103, but so
is the the fuel pump and fuel level sender down at the tank. (!) SIDE NOTE: G404 looks to only be involved
if you have the balance relay & pump associated with the dual tank option?

Since we've already discussed the G200 fanout, so now that we're interested in G103, what does the ground
distribution fanout look like for this one? (See attached.)

****

I'm up against the 5 pic limit, so in the next reply I'll share the physical location info and tie this all together.

 

[Road Trip]

OK, I put in a carquest pump as I was stranded. It works, the truck runs, I'm happy.
I guess nobody has any idea of why the gauge jumps when I foot the brake pedal. Hunh?

(Answer, Part II)

So we've aired out what the cab-centric G200 ground does for us.
And we just took a good look at what G103 & G104 mean to the gas delivery / gas gauge circuit.

But I'm still trying to prove via the General's wiring diagrams why ETA's recommendation to clean
the grounds that the actual taillights ('Stoplamps') rely upon is a good one. (And for myself, why
does the FSM mention G404, but not G401, aka the ground for all the lights out back?)

It took a while. But I don't feel embarrassed about that, for the way this circuit is drawn it is not
troubleshooter friendly at all. And if you ask me to look into a car where both brake lights aren't
working despite known-good bulbs, my default mental block diagram is:
Fused Power > brake pedal switch > bulbs.

And on the GMT400 I would be wrong. Check out the path that is navigated when we step on the brake pedal and
we want the taillights to dazzle the safety inspector with their prompt brilliance:

(excerpt from the '97 FSM)

You must be registered for see images attach

Signal path for a pickup: Brake pedal switch out C100 > Stoplamp relay in the Underhood Fuse Block,
followed by the mixmaster magic in the *Turn/Hazard Switch* > then out to the taillights.

Yikes. That aging turn/hazard switch is to electricity in the GMT400 as the college cafeteria is to where food
fights erupt. Anything strange in there can happen inside one of those switches (that's got 10s of
thousands of cycles on it accumulated over the years since it was built) ...and I'm not the least bit surprised.
:0)

And the stoplamp signal was sent through the turn/hazard switch so that the last 2 sentances in
the description above could be implemented. And for anyone interested, here's the following 2 wiring
diagrams that are supposed to convey the same Theory of Operation above to you the troubleshooter:

You must be registered for see images attach

You must be registered for see images attach

That's all I got. I'm sure that there's a much more precise answer available...but at the same time
I don't think anyone is still with me while slogging through this rainforest of a wiring diagram.

****

Seriously, I'm curious about the fuel gauge misbehavior. Which of the 4 categories would it
fall under?

A) Momentary spike in the gas gauge fuel level quantity when foot first depresses brake,
returning to the proper reading almost immediately?
B) Gas gauge drops lower when brake pedal is depressed, and stays lower until brake pedal
is released?
C) Gas gauge rises higher when brake pedal is depressed, and stays higher until brake pedal
is released?
D) None of the above. So what does the gauge actually do when the disturbance is observed?

Hopefully the above gives you a better idea of how an electrical gremlin between the brake
pedal and the gas gauge on your dash can occur in a GMT400 vehicle.

Looking forward to what you discover. Best of luck --

PS - The above was not written to persuade you to swap that switch. I'm just happy to be
one step closer to being able to explain how a marginal G401 ground can make such weird
stuff happen elsewhere. And if anyone else wants to jump in and accuratize any of the above,
please don't hesitate, be my guest.

 

[62barsoom]

(Answer, Part II)

So we've aired out what the cab-centric G200 ground does for us.
And we just took a good look at what G103 & G104 mean to the gas delivery / gas gauge circuit.

But I'm still trying to prove via the General's wiring diagrams why ETA's recommendation to clean
the grounds that the actual taillights ('Stoplamps') rely upon is a good one. (And for myself, why
does the FSM mention G404, but not G401, aka the ground for all the lights out back?)

It took a while. But I don't feel embarrassed about that, for the way this circuit is drawn it is not
troubleshooter friendly at all. And if you ask me to look into a car where both brake lights aren't
working despite known-good bulbs, my default mental block diagram is:
Fused Power > brake pedal switch > bulbs.

And on the GMT400 I would be wrong. Check out the path that is navigated when we step on the brake pedal and
we want the taillights to dazzle the safety inspector with their prompt brilliance:

(excerpt from the '97 FSM)

You must be registered for see images attach

Signal path for a pickup: Brake pedal switch out C100 > Stoplamp relay in the Underhood Fuse Block,
followed by the mixmaster magic in the *Turn/Hazard Switch* > then out to the taillights.

Yikes. That aging turn/hazard switch is to electricity in the GMT400 as the college cafeteria is to where food
fights erupt. Anything strange in there can happen inside one of those switches (that's got 10s of
thousands of cycles on it accumulated over the years since it was built) ...and I'm not the least bit surprised.
:0)

And the stoplamp signal was sent through the turn/hazard switch so that the last 2 sentances in
the description above could be implemented. And for anyone interested, here's the following 2 wiring
diagrams that are supposed to convey the same Theory of Operation above to you the troubleshooter:

You must be registered for see images attach

You must be registered for see images attach

That's all I got. I'm sure that there's a much more precise answer available...but at the same time
I don't think anyone is still with me while slogging through this rainforest of a wiring diagram.

****

Seriously, I'm curious about the fuel gauge misbehavior. Which of the 4 categories would it
fall under?

A) Momentary spike in the gas gauge fuel level quantity when foot first depresses brake,
returning to the proper reading almost immediately?
B) Gas gauge drops lower when brake pedal is depressed, and stays lower until brake pedal
is released?
C) Gas gauge rises higher when brake pedal is depressed, and stays higher until brake pedal
is released?
D) None of the above. So what does the gauge actually do when the disturbance is observed?

Hopefully the above gives you a better idea of how an electrical gremlin between the brake
pedal and the gas gauge on your dash can occur in a GMT400 vehicle.

Looking forward to what you discover. Best of luck --

PS - The above was not written to persuade you to swap that switch. I'm just happy to be
one step closer to being able to explain how a marginal G401 ground can make such weird
stuff happen elsewhere. And if anyone else wants to jump in and accuratize any of the above,
please don't hesitate, be my guest.

Haven't had a chance to look into this yet. And now that my brains been warped I may not. The trip meter does work.

 

[Road Trip]

Haven't had a chance to look into this yet. And now that my brains been warped I may not. The trip meter does work.

Sir,

Just got to approach this Lewis & Clark style. The longest journey starts with the first step & all that.

Listen, I'm serious when I say that 12 volt DC circuits are my favorite to troubleshoot. We aren't worried about
AC circuit impedance, frequency response, transmission line theory, standing waves, GHz waveguide magic, etc.

I happened across a short video that is so clear & concise about how to quantify the health of the ground side of a 12v DC circuit.

I know that you are a well-adjusted, normal, non-sparky type, so don't tense up when this video starts. Just ride the wave,
this guy speaks in English not jibberish, the entire presentation builds to a logical conclusion, he proves his point using a very simple
example circuit, and if you can add this single skill to your electrical troubleshooting repertoire, *we* can get through this.

xc_hide_links_from_guests_guests_error_hide_media

In a perfect world, not only do we replace, plugs, oil, filters, caps, rotors, tires, even paint, windshields, etc in order to keep our
GMT400s looking and running like new, we would also be able to completely yet easily replace the aging wiring harness too.

But this is the real world, so everyone in here reading this (as of this writing) gets to deal with a 22-36 year old wiring harness,
and replacing the entire wiring harness is a difficult, rare and notable event. And if I seem a bit pollyanna about all this, the last
dozen years of my military career I was doing the same thing for Block 25 & Block 32 F-16s back when they were showing
unmistakable signs of wiring harness aging.

When I left the computer room & rejoined the military right after 9/11, I was being asked by leadership why the Avionics package was
the LIMFAC to our fleet's reliability. I would take the officer out to the tail in question (see attached for an example) point out the year
it was made (2 digit numeral under the 'AF') and simply explain to them that because of the endless new tires, canopies, engines, paint,
etc., our planes did *look* new...but then I'd take them to anywhere there was wiring harness showing under an open panel (most places)
...and I would simply explain that nearly ALL of that wiring was installed that many years ago on the assembly line in Fort Worth, TX by
a company named General Dynamics.

Note: At the time the aircraft were also 20-somethings, and given the 9g loads and routinely being pushed as hard as possible, these
planes aged more like F1 cars instead of Nana's gently driven grocery getter. The officer would understand what we were up against.

In response to these concerns, we really put a lot of focus on tracking down and fixing non-black box intermittents reported by the
pilots in Debrief, instead of just waving them off as a MUC. (Momentary Undesirable Condition, a real thing at the end of some
troubleshooting flowcharts.) And with unrelenting focus in this area we were able over time to get our planes back to the way
they were when they were new. Black box go bad, we put known-good Black Box in, plane worky again. We wanted to remain a
manned fighter wing, instead of being moved to do a different mission, or worst-case being BRAC'd out of existence. So we were
highly motivated to make the very most of what we were given to work with. :0)

****

So apologies if my warped sense of humor made me color your perspective by referring to this area as a wiring diagram rainforest. I've
actually read elsewhere in this forum a talented member lead us all through a multifunction switch issue neatly. And if you were my pilot
and you mentioned any of the gauges in the cockpit moving when you did something else logically unrelated, that's where I'd ask you
if the suspect gauge just momentarily jump, or did it stay high -or- low until you ceased the (unrelated) input?

****

Of course the signals were more complex, but at the same time I was there, first-person, shoulder to shoulder with the users, other
flightline maintainers, and my own team. Here, we are all doing this remotely, relying upon the written word, pics, and sometimes
even video while using the FSMs. Personally, although the troubleshooting subject matter is something I got to do my entire military
& civilian career, at the same time I'm a newbie to the remote troubleshooting realm, and I'm still learning the ropes of how to do this
in such a way as to minimize the inevitable frustrations that come from not being able to see/touch/smell/etc the problem at hand.
And at the scene of the crime, most of us are working solo, which takes extra focus & patience to pull off this kind of thing.

And I never thought that I'd be doing this in public. But then again I never thought that even a vinyl-floored new chore truck would be so
far on the other side of $50K? And I've had to be careful with my own finances all my life, so I know what's it like to not have the option
of using the wallet wrench to get me out of a bind.

So here we are. As a motivated lurker I got way more than my fair share of hard-won info from this forum. And truth be told, I *still* enjoy a
challenging troubleshooting session and premeditated fix after all these years. And I decided that I had finally found a place where I
wanted to join the party already in progress. Especially with fellow GMT400 enthusiasts and straight up solid folks such as yourself.
So watch that video, maybe sleep on it, watch it again, and think about building up a little test circuit like he did in order to reinforce
what he was sharing...and if you have any questions, then I'll do my best to answer them.

Believe me, electrical gremlins used to ground airplanes and also keep me from driving a new (to me) well-used vehicle no further away from
my abode than I was willing to walk back home if need be. But being able to take something like an old Fiat Spider halfway across country
in order to attend some mandatory 7-level training was a hoot.

Apologies for the length. I'm hoping that between the all of us we can figure out the answer to your simple question about how
your foot on the brake pedal disturbs the fuel quantity reported by the gas gauge. :0)

Because if we can do that, then we will have honed our skills for sorting out other aging GMT400 wiring harness issues. And being able
to drive our old GMT400s without constant worrying about the electrical system failing us is a worthwhile goal.

Cheers --

PS - F-16 Wiki article.

 

[Erik the Awful]

I just rewired the top end of my wife's old Chrysler 300 (about to become my daughter's car) because the harness was breaking down after only 15 years.

The engine harnesses in our trucks are actually replaceable. The wiring harness on my wife's car? Not so much. It's a freaking octopus that goes through the firewall and into the car. Not worth replacing, so I had to do a crapload of splicing. They're throwaway cars, which I'm pretty sure is Chrysler's goal. I'm not likely to buy another Chrysler because of it.

 

[62barsoom]

Sir,




Sir,

Just got to approach this Lewis & Clark style. The longest journey starts with the first step & all that.

Listen, I'm serious when I say that 12 volt DC circuits are my favorite to troubleshoot. We aren't worried about
AC circuit impedance, frequency response, transmission line theory, standing waves, GHz waveguide magic, etc.

I happened across a short video that is so clear & concise about how to quantify the health of the ground side of a 12v DC circuit.

I know that you are a well-adjusted, normal, non-sparky type, so don't tense up when this video starts. Just ride the wave,
this guy speaks in English not jibberish, the entire presentation builds to a logical conclusion, he proves his point using a very simple
example circuit, and if you can add this single skill to your electrical troubleshooting repertoire, *we* can get through this.

xc_hide_links_from_guests_guests_error_hide_media

In a perfect world, not only do we replace, plugs, oil, filters, caps, rotors, tires, even paint, windshields, etc in order to keep our
GMT400s looking and running like new, we would also be able to completely yet easily replace the aging wiring harness too.

But this is the real world, so everyone in here reading this (as of this writing) gets to deal with a 22-36 year old wiring harness,
and replacing the entire wiring harness is a difficult, rare and notable event. And if I seem a bit pollyanna about all this, the last
dozen years of my military career I was doing the same thing for Block 25 & Block 32 F-16s back when they were showing
unmistakable signs of wiring harness aging.

When I left the computer room & rejoined the military right after 9/11, I was being asked by leadership why the Avionics package was
the LIMFAC to our fleet's reliability. I would take the officer out to the tail in question (see attached for an example) point out the year
it was made (2 digit numeral under the 'AF') and simply explain to them that because of the endless new tires, canopies, engines, paint,
etc., our planes did *look* new...but then I'd take them to anywhere there was wiring harness showing under an open panel (most places)
...and I would simply explain that nearly ALL of that wiring was installed that many years ago on the assembly line in Fort Worth, TX by
a company named General Dynamics.

Note: At the time the aircraft were also 20-somethings, and given the 9g loads and routinely being pushed as hard as possible, these
planes aged more like F1 cars instead of Nana's gently driven grocery getter. The officer would understand what we were up against.

In response to these concerns, we really put a lot of focus on tracking down and fixing non-black box intermittents reported by the
pilots in Debrief, instead of just waving them off as a MUC. (Momentary Undesirable Condition, a real thing at the end of some
troubleshooting flowcharts.) And with unrelenting focus in this area we were able over time to get our planes back to the way
they were when they were new. Black box go bad, we put known-good Black Box in, plane worky again. We wanted to remain a
manned fighter wing, instead of being moved to do a different mission, or worst-case being BRAC'd out of existence. So we were
highly motivated to make the very most of what we were given to work with. :0)

****

So apologies if my warped sense of humor made me color your perspective by referring to this area as a wiring diagram rainforest. I've
actually read elsewhere in this forum a talented member lead us all through a multifunction switch issue neatly. And if you were my pilot
and you mentioned any of the gauges in the cockpit moving when you did something else logically unrelated, that's where I'd ask you
if the suspect gauge just momentarily jump, or did it stay high -or- low until you ceased the (unrelated) input?

****

Of course the signals were more complex, but at the same time I was there, first-person, shoulder to shoulder with the users, other
flightline maintainers, and my own team. Here, we are all doing this remotely, relying upon the written word, pics, and sometimes
even video while using the FSMs. Personally, although the troubleshooting subject matter is something I got to do my entire military
& civilian career, at the same time I'm a newbie to the remote troubleshooting realm, and I'm still learning the ropes of how to do this
in such a way as to minimize the inevitable frustrations that come from not being able to see/touch/smell/etc the problem at hand.
And at the scene of the crime, most of us are working solo, which takes extra focus & patience to pull off this kind of thing.

And I never thought that I'd be doing this in public. But then again I never thought that even a vinyl-floored new chore truck would be so
far on the other side of $50K? And I've had to be careful with my own finances all my life, so I know what's it like to not have the option
of using the wallet wrench to get me out of a bind.

So here we are. As a motivated lurker I got way more than my fair share of hard-won info from this forum. And truth be told, I *still* enjoy a
challenging troubleshooting session and premeditated fix after all these years. And I decided that I had finally found a place where I
wanted to join the party already in progress. Especially with fellow GMT400 enthusiasts and straight up solid folks such as yourself.
So watch that video, maybe sleep on it, watch it again, and think about building up a little test circuit like he did in order to reinforce
what he was sharing...and if you have any questions, then I'll do my best to answer them.

Believe me, electrical gremlins used to ground airplanes and also keep me from driving a new (to me) well-used vehicle no further away from
my abode than I was willing to walk back home if need be. But being able to take something like an old Fiat Spider halfway across country
in order to attend some mandatory 7-level training was a hoot.

Apologies for the length. I'm hoping that between the all of us we can figure out the answer to your simple question about how
your foot on the brake pedal disturbs the fuel quantity reported by the gas gauge. :0)

Because if we can do that, then we will have honed our skills for sorting out other aging GMT400 wiring harness issues. And being able
to drive our old GMT400s without constant worrying about the electrical system failing us is a worthwhile goal.

Cheers --

PS - F-16 Wiki article.

Road Trip thanks so much for taking your time with this I will definitely follow your suggestions. I'm not completely ignorant of the magic smoke, so hopefully I'll be able to understand all of that.

Thanks again
Jim

 

[JDGMC]

Sir,




Sir,

Just got to approach this Lewis & Clark style. The longest journey starts with the first step & all that.

Listen, I'm serious when I say that 12 volt DC circuits are my favorite to troubleshoot. We aren't worried about
AC circuit impedance, frequency response, transmission line theory, standing waves, GHz waveguide magic, etc.

I happened across a short video that is so clear & concise about how to quantify the health of the ground side of a 12v DC circuit.

I know that you are a well-adjusted, normal, non-sparky type, so don't tense up when this video starts. Just ride the wave,
this guy speaks in English not jibberish, the entire presentation builds to a logical conclusion, he proves his point using a very simple
example circuit, and if you can add this single skill to your electrical troubleshooting repertoire, *we* can get through this.

xc_hide_links_from_guests_guests_error_hide_media

In a perfect world, not only do we replace, plugs, oil, filters, caps, rotors, tires, even paint, windshields, etc in order to keep our
GMT400s looking and running like new, we would also be able to completely yet easily replace the aging wiring harness too.

But this is the real world, so everyone in here reading this (as of this writing) gets to deal with a 22-36 year old wiring harness,
and replacing the entire wiring harness is a difficult, rare and notable event. And if I seem a bit pollyanna about all this, the last
dozen years of my military career I was doing the same thing for Block 25 & Block 32 F-16s back when they were showing
unmistakable signs of wiring harness aging.

When I left the computer room & rejoined the military right after 9/11, I was being asked by leadership why the Avionics package was
the LIMFAC to our fleet's reliability. I would take the officer out to the tail in question (see attached for an example) point out the year
it was made (2 digit numeral under the 'AF') and simply explain to them that because of the endless new tires, canopies, engines, paint,
etc., our planes did *look* new...but then I'd take them to anywhere there was wiring harness showing under an open panel (most places)
...and I would simply explain that nearly ALL of that wiring was installed that many years ago on the assembly line in Fort Worth, TX by
a company named General Dynamics.

Note: At the time the aircraft were also 20-somethings, and given the 9g loads and routinely being pushed as hard as possible, these
planes aged more like F1 cars instead of Nana's gently driven grocery getter. The officer would understand what we were up against.

In response to these concerns, we really put a lot of focus on tracking down and fixing non-black box intermittents reported by the
pilots in Debrief, instead of just waving them off as a MUC. (Momentary Undesirable Condition, a real thing at the end of some
troubleshooting flowcharts.) And with unrelenting focus in this area we were able over time to get our planes back to the way
they were when they were new. Black box go bad, we put known-good Black Box in, plane worky again. We wanted to remain a
manned fighter wing, instead of being moved to do a different mission, or worst-case being BRAC'd out of existence. So we were
highly motivated to make the very most of what we were given to work with. :0)

****

So apologies if my warped sense of humor made me color your perspective by referring to this area as a wiring diagram rainforest. I've
actually read elsewhere in this forum a talented member lead us all through a multifunction switch issue neatly. And if you were my pilot
and you mentioned any of the gauges in the cockpit moving when you did something else logically unrelated, that's where I'd ask you
if the suspect gauge just momentarily jump, or did it stay high -or- low until you ceased the (unrelated) input?

****

Of course the signals were more complex, but at the same time I was there, first-person, shoulder to shoulder with the users, other
flightline maintainers, and my own team. Here, we are all doing this remotely, relying upon the written word, pics, and sometimes
even video while using the FSMs. Personally, although the troubleshooting subject matter is something I got to do my entire military
& civilian career, at the same time I'm a newbie to the remote troubleshooting realm, and I'm still learning the ropes of how to do this
in such a way as to minimize the inevitable frustrations that come from not being able to see/touch/smell/etc the problem at hand.
And at the scene of the crime, most of us are working solo, which takes extra focus & patience to pull off this kind of thing.

And I never thought that I'd be doing this in public. But then again I never thought that even a vinyl-floored new chore truck would be so
far on the other side of $50K? And I've had to be careful with my own finances all my life, so I know what's it like to not have the option
of using the wallet wrench to get me out of a bind.

So here we are. As a motivated lurker I got way more than my fair share of hard-won info from this forum. And truth be told, I *still* enjoy a
challenging troubleshooting session and premeditated fix after all these years. And I decided that I had finally found a place where I
wanted to join the party already in progress. Especially with fellow GMT400 enthusiasts and straight up solid folks such as yourself.
So watch that video, maybe sleep on it, watch it again, and think about building up a little test circuit like he did in order to reinforce
what he was sharing...and if you have any questions, then I'll do my best to answer them.

Believe me, electrical gremlins used to ground airplanes and also keep me from driving a new (to me) well-used vehicle no further away from
my abode than I was willing to walk back home if need be. But being able to take something like an old Fiat Spider halfway across country
in order to attend some mandatory 7-level training was a hoot.

Apologies for the length. I'm hoping that between the all of us we can figure out the answer to your simple question about how
your foot on the brake pedal disturbs the fuel quantity reported by the gas gauge. :0)

Because if we can do that, then we will have honed our skills for sorting out other aging GMT400 wiring harness issues. And being able
to drive our old GMT400s without constant worrying about the electrical system failing us is a worthwhile goal.

Cheers --

PS - F-16 Wiki article.

Remote troubleshooting in this forum can be challenging. Limited physical access and the person's ability to describe the problem with the minimum information required to start the process can be a problem in itself. The what, when, where and conditions are likely not available in the post for help. For this forum, the first step is always collecting all the information required to make an informed assessment. Without it, the probable cause required to physically test the solution is hit or miss. In industry, procedures, forms and guides are used that are tailored to the specifics of a particular component or service. Typically written by the manufacturer and re-worded for company or government use. Likely why GM manuals aren’t so great with many revisions. Here, people do their best to provide a comprehensive path, but a form and a GOPRO would go a long way.

 

[Caman96]

@Road Trip Rules!
Not sure why that’s not highlighted^^^.