2007 Trailblazer, 4.2L, 4X4, 3.43 non-locking rear end, 285K miles
This has happened twice in the last 6 months. There are no apparent bad sounds such as whining or grinding when normally driving and I haven’t used AWD or 4Hi in over a year. After making a hard stop, once for a changing traffic light and once to avoid hitting another vehicle pulling out of a parking space in a parking lot, the drivetrain completely locked up. In other words, I stabbed the brakes and then when I tried to move forward afterwards, the truck would not move forward. It felt like the trans was straining and trying to move the truck, but something in the drivetrain was locked preventing the truck from moving forward. All I had to do to unlock it was to move the shifter to reverse and then back to drive and all seemed normal. I did not let the truck roll backwards when in reverse, still had brakes applied, so this is not a brake issue. I changed the rear diff fluid about 15K ago and noticed a little slop in the spider gears but didn’t see any broken teeth in the ring or pinion. I suppose that it might be possible that the spider gears are getting jammed, but I don’t think that would cause a total lockup since the truck was pointed straight and the carrier should still have been able to turn regardless of the spider gears. There are no obvious signs of problems with the driveshaft. I haven’t opened the rear differential yet since this happened, but I was wondering if an issue in the transfer case could also cause this? I kind of hate having to start tearing things apart without knowing the general root cause. I suppose that it could also be a trans issue too, but think that’s unlikely. I have tried to intentionally recreate this in my driveway but have had no success. Anyone have any ideas or come across this type of thing before?
This has happened twice in the last 6 months. There are no apparent bad sounds such as whining or grinding when normally driving and I haven’t used AWD or 4Hi in over a year. After making a hard stop, once for a changing traffic light and once to avoid hitting another vehicle pulling out of a parking space in a parking lot, the drivetrain completely locked up. In other words, I stabbed the brakes and then when I tried to move forward afterwards, the truck would not move forward. It felt like the trans was straining and trying to move the truck, but something in the drivetrain was locked preventing the truck from moving forward. All I had to do to unlock it was to move the shifter to reverse and then back to drive and all seemed normal. I did not let the truck roll backwards when in reverse, still had brakes applied, so this is not a brake issue. I changed the rear diff fluid about 15K ago and noticed a little slop in the spider gears but didn’t see any broken teeth in the ring or pinion. I suppose that it might be possible that the spider gears are getting jammed, but I don’t think that would cause a total lockup since the truck was pointed straight and the carrier should still have been able to turn regardless of the spider gears. There are no obvious signs of problems with the driveshaft. I haven’t opened the rear differential yet since this happened, but I was wondering if an issue in the transfer case could also cause this? I kind of hate having to start tearing things apart without knowing the general root cause. I suppose that it could also be a trans issue too, but think that’s unlikely. I have tried to intentionally recreate this in my driveway but have had no success. Anyone have any ideas or come across this type of thing before?