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About intheburbs

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  1. Not an electrician, just a geek who knows enough to be dangerous. It sounds like what you want to do is the exact opposite of the way the truck is wired. It would probably be easier and cheaper to just swap out the deep cycle battery and not try to swim upstream. I have two AGM batteries (a total of 4) in each of my two trucks. Have never had any issues in the last five years, and just recently, finally, had to replace one of them. The only times I've even handled jumper cables or battery starters were to help others with dead batteries.
  2. I was not aware of the AGM thing with GMT900. I have two trucks, each with 2 AGM batteries. I've had the two AGM batteries in my Suburban for over 5 years with no issues. Here's the writeup I used, and added some additional information of my own. All OEM parts, so it's as if the truck came with TP2. The 2nd battery is isolated when the ignition is off, so all aux loads pull from the primary, and the secondary is held in reserve as the start battery. https://chevroletforum.com/forum/tahoe-suburban-diy-useful-threads-61/aux-battery-tp2-upgrade-65109/
  3. Page 9-97 of the owners manual. Just google it for a pdf. The entire manual is too big to attach here, so here's the pertinent page. You also need to know: - axle ratio - HD cooling package? - max trailering package? 6.2LV8 3.42 6,400 lbs 6.2LV8 K5L HD Cooling Pkg 3.42 9,400 6.2LV8 NHT Max Trailering Pkg 3.73 10,400 lbs 2011_gmc_sierra_owner trailer.pdf
  4. If you have a flex-fuel engine, you would see a power bump running E85, but also a big-time drop in mileage. Not sure the 5.3 is even programmed to take advantage of premium gas, so I question whether you'd see any bump in mileage or power without a custom PCM tune. I did do a "hot" tune on my 2001 Suburban, trying to get a little extra when towing our 4500-lb RV. The reason you can even buy 85 octane in high-altitude states like Colorado is that the thinner air makes 85 octane behave the same as 87 at sea level. 85 octane won't hurt a thing. I lived in Colorado for 10 years, have a little bit of experience driving in high altitudes.
  5. I just went with the blue/yellow Bilstein 4600s on all four corners. Huge improvement on ride/porpoising when towing. I tow an 8600-lb trailer.
  6. Guess I just got lucky on my 4L60. 260,000 miles, still original, still shifts perfectly, and I abused that thing so much towing heavy stuff that it's on its fourth rear end. 2001 Suburban, now owned by a friend. Original engine, too.
  7. I see two likely candidates, both happened with my '01 Suburban, on separate occasions. 1) The brake lines are prone to rust and can fail. 2) The master cylinder failed ETA: DOT3 brake fluid doesn't boil until over 400° F. Nothing short of an engine fire will boil it off.
  8. It's a 6.2L truck with 400 hp, not a Prius. Running the A/C has nothing to do with it. You're going to get crappy mileage. Period. Bonus points because premium is recommended. My Denali gets about 12 MPG around town. When I floor the throttle, I swear I can see the gas needle moving. If I try really hard, set the cruise at 65, with a tail wind, maybe it'll get me 15-16 mpg on the highway. But you know what? I don't care. It's a blast to drive and every time I stomp the throttle it puts a big, stupid smile on my face. Only complaint is the range. At least my Suburban has a 39-gallon tank, so I still have a range of 500+ miles. With only 26 gallons in the Denali, I'm lucky to get 300 miles out of a tank.
  9. I say run what you brung. You have the heavy duty cooling package (KNP) and 3.73 gears (GT4). Sure the transmission has a lot of miles on it - any mods to improve engine output will just accelerate failure. If the transmission blows up, it blows up. No point in throwing money into it now. With the trailer, you're at about 5000 lbs. Assuming you'll go flatbed, not enclosed, the truck should tow that pretty well. See how it does, how the temps run, and then assess and plan your mods.
  10. I hate to be Captain Obvious, but do you have fresh batteries in the fobs?
  11. Well, as a guy who makes a living selling seals, o-rings and gaskets, I can tell you the requirements for seals have gotten more challenging over the years. The OEMs are not just slapping in junk. And my '08 Suburban has 192,000 miles on the original axle seals.
  12. Agree. I've logged over 20,000 miles on this truck towing heavy, including multiple trips over the Rockies and the Eisenhower tunnel. Truck is frighteningly all original with 190k on the clock. And I'll be dragging the behemoth trailer back out to Wyoming in June.
  13. If I run mine (the 2500 Suburban) long enough to get up to "operating temperature," it usually ends up being about 100° over the outside temps. So in the winter, it's running around 120°-130°. In the summer, it's running 190°-200°. Towing is another matter, I've had it as high as 241° pulling up long grades in the Rockies with an 8600-lb trailer. All that being said, GM designed these things for an operating temperature of 190°-200°. That's what they consider "normal operating parameters." So as the poster above said, be happy yours is running cooler. No real downside, other than you might not be cooking off any condensation/moisture in the system.
  14. As an owner of two GMT900 trucks, one with 4WD and one with AWD, I've made the same comparisons and have come to the same conclusions. Yes, the 4WD Suburban is better in bad weather. I think there are two main factors on this: 1) Tires 2) The center differential on the AWD system 1) The Denalis come with street tires, not mud/snow/all-terrain tires. They're large diameter, low profile, and there aren't a lot of snow/mud tire options for that size. Plus, even if you did find one, they'd probably look ridiculous. Can you picture Goodyear Duratracs on a Denali pickup with 20" wheels? The tires on the Denali are also wider, 275 vs 245, at least on my Suburban, and narrow is always better in low-traction situations. Narrower means less hydroplaning and a higher load on the contact patch of the tire. My Denali is wearing Michelin LTX MS/2s from Costco, and they seem to be an improvement. But my Suburban has Goodyear Duratracs, and it's basically unstoppable in snow. I've driven on unplowed roads and parking lots as deep as 16" with no issues. But again, it's 1000 lbs heavier, riding on narrower tires. 2) As said on a previous post, the AWD system introduces a third differential into the powertrain. This means, theoretically, that if you have one tire slipping, it can be the only one moving and you could be stuck. Now, the G80 rear will help, but the only way you have of "simulating" a locking of the center or front differential is the Traction Control/Stabilitrak/ABS system applying the brakes to the spinning wheel(s). And my experience is that the system is slow/unwilling to fully clamp onto a spinning wheel. Bottom line - if my Denali was my only vehicle, and I needed to get around in the winter, I'd probably sell it and get something else with no center diff. But as you can see in my sig, for me, I have plenty of other good options for bad weather. I consider the Denali my "hot rod," and it usually sits in really bad weather. PS - Everyone does know that pressing and holding the Stabilitrak button for five seconds pretty much disables the entire system, right? From my Denali owners manual, page 4-7:
  15. If the check engine light is on, no remote start. If you clear the light, it should start. However, if the problem is detected when the truck powers up, prior to starting, then you'll get the same light flash and no start. It also won't start if the fuel light is on.
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