Odd Grinding Noise from rear wheels when in AWD

icojones · 10-18-2005, 11:13 AM

I have an odd grinding noise that comes from the rear wheel area when my 2002 Trailblazer is in AWD and the wheel is turned more than a half turn or so. The noise goes away when in 2-wheel drive and I have not tested to see if it is there in 4-HI or 4-Lo.

I'm sure this will end up as a bigtime repair (everything seems to be), but I wanted to check here to see if it sounded familiar to anyone.

Thanks,

IcoJones

maxwedge · 10-18-2005, 11:52 AM

Do you feel any binding or shudder when this happens?

icojones · 10-18-2005, 12:05 PM

yes. It almost feels like the tires are hitting the mudflaps, but they are not. Sounds bad, huh? Is it dangerous?

maxwedge · 10-18-2005, 01:46 PM

Does it shudder or feel like you are on dry pavement like in 4wd, if so the transfer case encoder and programming could be at fault here.

ScarabEpic22 · 10-19-2005, 01:43 AM

OK, TrailBlazers do not have AWD, they have 4WD. 2HI, A4WD, 4HI, and 4LOW are the options, with A4WD being automatic 4WD. It detecs slipping of the rear wheels and engages the front wheels.

maxwedge · 10-19-2005, 08:38 AM

There has been a problem with the encoder motors in the transfer case, when in a4wd they are engaging the 4wd erroneously, causing this binding, there is TSB referring to this condition.

ScarabEpic22 · 10-19-2005, 11:22 PM

maxwedge, I think I am having that problem some times. I can look down at the 4WD indicator when I am in A4WD, and the light will be at 4HI, while the switch is at A4WD. I think I will look into a PCM update to fix this and take a peek at my TSBs.

maxwedge · 10-20-2005, 11:53 AM

Scarab this sounds more like the dash selector switch also a common problem on these trucks ,again a tsb for this also.

ScarabEpic22 · 10-20-2005, 10:11 PM

thanks man, I am going to get a new transfer case switch and see if the problem is fixed. If not, then I will look for deeper issues.

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