AFoldedLawnChair
Newbie
99 tahoe
4wd autotrac
5.7
No Service 4x4 light
So the truck drives just fine under its own power but has a loud rattling or hissing sound while the light on the dash says 2wd or 4hi. It won't engage 4lo or autotrac but I know for sure the sound is drivetrain related as it only happens when the truck is in motion. I assumed it was something minor as inside the cab it isn't that loud, however after driving it for a while I've noted a few things and just need some direction on where to start looking. trans and transfer case fluids are fine FYI.
the sound happens 100% consistently from the slowest crawl all the way to 75ish mph and the pitch of the click, hiss, or rattle does vary with speed, but what has me confused is after about 7 to 10 miles at between 55 to 70mph the truck suddenly "clunked", it was heard and felt but wasn't something that scared me enough to pull over and check the driveline. After the "clunk" the truck ran dead silently, no rattles, no hissing no noise just a calm smooth ride, and this exact event happened twice during a 25 to 30 miles ride. It ran so smooth and perfect that I'm willing to chase this issue and keep my truck rather than junking it.
My question is, could this be a specific piece of the 4x4 assembly? I'm the mechanic of my family and friend group but this is my first AWD vehicle so I'm not quite familiar with their eccentricities and unique parts. I have plenty of tools and scan tools so I really just want a good starting guide to start troubleshooting this issue into nonexistence.
Thanks!
4wd autotrac
5.7
No Service 4x4 light
So the truck drives just fine under its own power but has a loud rattling or hissing sound while the light on the dash says 2wd or 4hi. It won't engage 4lo or autotrac but I know for sure the sound is drivetrain related as it only happens when the truck is in motion. I assumed it was something minor as inside the cab it isn't that loud, however after driving it for a while I've noted a few things and just need some direction on where to start looking. trans and transfer case fluids are fine FYI.
the sound happens 100% consistently from the slowest crawl all the way to 75ish mph and the pitch of the click, hiss, or rattle does vary with speed, but what has me confused is after about 7 to 10 miles at between 55 to 70mph the truck suddenly "clunked", it was heard and felt but wasn't something that scared me enough to pull over and check the driveline. After the "clunk" the truck ran dead silently, no rattles, no hissing no noise just a calm smooth ride, and this exact event happened twice during a 25 to 30 miles ride. It ran so smooth and perfect that I'm willing to chase this issue and keep my truck rather than junking it.
My question is, could this be a specific piece of the 4x4 assembly? I'm the mechanic of my family and friend group but this is my first AWD vehicle so I'm not quite familiar with their eccentricities and unique parts. I have plenty of tools and scan tools so I really just want a good starting guide to start troubleshooting this issue into nonexistence.
Thanks!
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