Getting +12V @ 50A in my 2017 Consume Tahoe

[wm8s]

I just opened the hood of my 2017 consumer Premium package C1500 5.3L Tahoe to look for a way to get +12V @ ~50A into the passenger compartment (for some radios, of course!).

I was quite happy to see that the battery is rigged very nicely to accept extra ring terminals.

Then I tried to find a way through the firewall. Daunting, to say the least.

(1) Before I reinvent the wheel at grave risk of damage to me and the truck, is there a better / easier / safer way? I know that the PPVs/5W4s had high-current studs in them in the passenger compartment for radios, etc. Mine's not one of those, but is there nevertheless already an available 40A or 50A circuit in the passenger compartment somewhere that I can find and use? [Searching through this and the "Pictures of your setup" forum with some obvious keywords didn't reveal an answer.]

(2) If not, (a) arg, and (b) what's the best way to go through the firewall? I've seen suggestions that there's an unused/spare grommet somewhere for just such purposes, but from standing over the engine, nothing leapt out at me.

Hoping for good news...

...R

EDIT: If I could find 25A, that would hold me for now.

 

[SurgePGH]

Have you looked above and to the left of the brake pedal from the inside? There is, in some cases, a round, covered hole where the clutch pedal assembly would pass through. The cover is usually plastic and is easy to get through. ALWAYS look at both sides several times and determine that there is nothing in your way.

 

[wm8s]

Have you looked above and to the left of the brake pedal from the inside? There is, in some cases, a round, covered hole where the clutch pedal assembly would pass through. The cover is usually plastic and is easy to get through. ALWAYS look at both sides several times and determine that there is nothing in your way.

I haven't tried looking from the other side yet. I was too disheartened by the view from the engine compartment. And yeh, no blind drilling!

Thanks.

...R

 

[wm8s]

Alas, I looked [or tried as much as physics and gerontology would allow] to no avail. I see where the brake pedal cable goes through, but there is so much other stuff all around it, including a thick ribbed plastic liner, that it wasn't promising. I have all of the upfitters' manuals; maybe they'll say something. I have a very long drill bit; maybe I'll just start drilling until something pops out somewhere ....

 

[wm8s]

I'd read this thread from earlier, and it shows a nipple grommet on the firewall in the engine compartment. I've located that grommet (with the nipple cap just waiting for me to snip it off and jam some wires through). But for the life of me, I can't see on the inside where it'll come out. I've pulled the inside fuse block cover and the knee bolster, and the area where I estimate the other side of that grommet is located is buried under a bunch of panels, dividers, etc.

Anyone ever done this and can shed some light? Thanks!

...R

 

[mmckenna]

I'd read this thread from earlier, and it shows a nipple grommet on the firewall in the engine compartment. I've located that grommet (with the nipple cap just waiting for me to snip it off and jam some wires through). But for the life of me, I can't see on the inside where it'll come out. I've pulled the inside fuse block cover and the knee bolster, and the area where I estimate the other side of that grommet is located is buried under a bunch of panels, dividers, etc.

Anyone ever done this and can shed some light? Thanks!

...R

If the Tahoe is the same as the Silverados, then the pass through point is up behind the glove box. Don't waste your time trying to take things apart looking for it, you'll have most of the dashboard removed before you get there.

It's much easier to fish through a piece of small gauge stranded wire from the engine compartment and then look for it from the inside under the glove box. Use a bright colored wire, and if you have access to a bore scope or one of those video cameras on a flexible stick tools, you'll find it up under there. I've done it on a few Silverados now. Use that wire to pull the larger cable through. It won't be easy, it's a tight fit, but with some persistence and appropriate use of well wielded cuss words, you will prevail.

I know for sure you can get a 6 gauge wire through there, and that'll support your 50 amps easily.

 

[wm8s]

Thanks, but I think it must be different. The grommet referred to and pictured in that other thread (and also in this one), which I can see from the engine side, is more or less behind the inside fuse panel, on the driver's side close to the driver's door, about halfway up.

 

[mmckenna]

Thanks, but I think it must be different. The grommet referred to and pictured in that other thread (and also in this one), which I can see from the engine side, is more or less behind the inside fuse panel, on the driver's side close to the driver's door, about halfway up.

OK, so there's two options:
1: Run the fish wire through that side and keep feeding it in and moving it around until you find it.
or
2. See if there's a similar pass through on the passenger side. Use the same technique.

 

[wm8s]

Yeh, I'd pretty much come to the conclusion that I'll have to try (1). Without a helper because of The Plague, this oughta be a challenge.

...R

 

[mmckenna]

Yeh, I'd pretty much come to the conclusion that I'll have to try (1). Without a helper because of The Plague, this oughta be a challenge.

...R

I recently procured one of these:

micro CA-150 Inspection Camera | RIDGID Tools

The RIDGID® micro CA-150 Inspection Camera allows you to perform more detailed visual inspections in even harder-to-reach areas. Shop now.

www.ridgid.com

Maybe not something you want to invest in, but if you know someone who has one, or maybe pick up one at Harbor Freight, they make life a bit easier. I used it on my brother in laws new Silverado to find the wire we were passing through his firewall. Also awesome for checking up above the headliner before installing an antenna mount.

Mobile install work is young guys work. I do it occasionally, but I pay for it dearly.
No shame in going to a professional radio installer and having them do it for you.

 

[KK6ZTE]

Mobile install work is young guys work. I do it occasionally, but I pay for it dearly.
No shame in going to a professional radio installer and having them do it for you.

I resemble that remark and I still pay for it dearly occasionally.

Late model GMs are the worst to run power cable through.

 

[wm8s]

You beat me to it. I was going to say, "You've obviously seen me...." At my age and in my condition, I'm not sure the parts of me that will need to can bend in the ways they're going to need to.

 

[mmckenna]

Our county shop often hires their installers out of the local dealership. Works out well, they know the cars, and can be taught the rest. Most of them end up being full fledged bench techs in short time.

I'm not that old, but I still feel it when I do an install, or even any sort of extended troubleshooting. Achy parts, cut up hands, etc. But even after all these years I find it rewarding.

 

[slowmover]

It’s easy to get under my pickup. But not getting back out. Ha!

Even this Peterbilt I have to build gumption.

If you don’t find a firewall pass-thru, then a Uni-Bit or Chassis Punch will work. I use Marine Cable Glands afterwards.

Securement against movement on both sides, is critical no matter how good “the grommet”. Cushioned Adel Clamps are preferred.

On either side of the firewall: no movement of the cable through the firewall. No in/out movement once secured. Then the work needed at either end.

The cabling needs to be of 105C or better rating, and should also be encased in FR split-loom.

A substitute for the actual cabling is the way to start. To lay it out and make notes. Marks.

Don’t expect to go in and out on first try. It’s at least three or more jobs.

1). Secure access and move other items to side.

2). Firewall + securemrnt points for the whole run.

3). Gentle installation and slack (neither too much nor too little) before attaching to vehicle.

Consider the thing as a harness the way the OEMs do it. I make mine removable: cable, covers & terminations all come out together in one piece.

So my routing isn’t torturous.

Also good to paint markers on it or label this to make underhood inspections easier.

And give yourself a time clock. No more than 90’ without a substantial break. Always be ready to stop RIGHT THEN.

Physical is bad. Emotional is worse.

Deducted tools & tool bags make RADIO much easier, IMO. A world all to its own.

.

 

[mmckenna]

The cabling needs to be of 105C or better rating

If you search for a cable with the SAE J1127 approval, it'll get you what you need.

 

[W4EMS]

Our county shop often hires their installers out of the local dealership. Works out well, they know the cars, and can be taught the rest. Most of them end up being full fledged bench techs in short time.

My Tacoma was also a bit daunting and I went to the dealership service manager who called a guy up and he showed me exactly where to thread thru as well as where NOT to go and where all of the airbags were in the headliner so we would not have any surprises installing the roof mount antenna. Worth the trip.
I only ran a hot wire electing to use the chassis ground near my rig. Would be rare to lose a chassis ground these days albeit it has probably happened to someone

 

[mmckenna]

Would be rare to lose a chassis ground these days albeit it has probably happened to someone

Yeah, it's rare. Usually when it happens it is because of years and years of neglected maintenance. Amateur radio operators often bring this up as a concern (disclaimer: I'm a ham, too) and will claim that corroded grounds will cause the starter to try to pull current through the radio. However, even the slightest amount of paying attention to what's going on under your hood will address that. It's one of the reasons many of us laugh at the "When all else fails" statement that some hams like so much.

 

[KK6ZTE]

My Tacoma was also a bit daunting and I went to the dealership service manager who called a guy up and he showed me exactly where to thread thru as well as where NOT to go and where all of the airbags were in the headliner so we would not have any surprises installing the roof mount antenna. Worth the trip.
I only ran a hot wire electing to use the chassis ground near my rig. Would be rare to lose a chassis ground these days albeit it has probably happened to someone

I've seen a new Dodge truck lose chassis ground in the body. ~9.2v in the cab, 13.5v in the engine bay/front fenders. Temporary fix was ground wire between body and frame until dealer could troubleshoot further.

 

[mmckenna]

Dodge truck

Well, there's your problem right there.

 

[slowmover]

Well, there's your problem right there.

Yeah (sigh) the only ones still roadworthy after a few years. Have to stay on top of them.

.