front axle pops unless 4x4 fuse pulled

[Sir William]

Mine does the same thing. If there's any load in any 4x4 mode and lack of traction in the rear, I'll get a loud POP from the transfer case as it applies power to the front. I'm guessing the chain has stretched after > 220K miles and is jumping a tooth. My hypothesis is that since the case was always in 4x4 Auto (no 2WD option in 1999), even turning in parking lots would put a little stress on the chain which slowly stretched it over time. I can validate this because with the fuse out or BWM done, it's much "smoother" turning at slow speeds on hard surfaces. So to those who haven't done it, do it!

The choice now is to rebuild a TC with more than a quarter million miles on it or swap in a lower mileage unit. The latter seems to make more sense.

 

[Texpedition45]

hey all,
2000 Eddie Bauer with a loud popping under load in any of the traction settings with little to no front wheel power.
it goes away with the engine bay 4x4 fuse pulled.
i assumed vacuum leak BUT... there is no actuator on the front axle! nor are there any solenoids on the fire wall.
my manual says there should be and there are not even mounts for it on the axle.
anybody have a setup like this?
im losing my mind here any help would be greatly appreciated.
thanks.

YOU DON'T HAVE ONE.

Caps for emphasis.

1997 to 1999.5 have the same vacuum actuated set up as the F150.

1999.5 to 2002 have a live axle set up (think Jeep).

Haynes, Chilton, etc. will still have the information of the first two years, not the last two of the first gen.

Your problem may be either:

1) the clutch in the TC.

2) the chain in the TC

3) the TC shift motor

4) the GEMS module

The last two work in concert: the TC shift motor engages and disengages the clutch in the TC. If it's faulty you will get issues with the TC engaging and disengaging when it shouldn't be. Same with the GEMS module.
Also keep in mind if your tires are not all the same size, and there's a 2% discrepancy in speed between the front and rear axle, your TC will try to engage, which will bind everything up (and make the same noise you described).

 

[dmeggers]

I had the same problem with my 2000 EB and took it to a trans shop and the tech told me it was the different sized tires. When I had to buy new tires (all the same size and make) presto, problem solved

 

[Sir William]

Once a chain is stretched, nothing will help. I had brand new tires all the way around and it will still pop if I engage 4x4 and get rear wheel slippage. The Auto 4x4 system works by measuring the difference in speed between the front and rear output shafts. There's nothing wrong with that specifically, but there is enough difference generated in a parking lot to partially engage the magnetic clutch and allow tension on the chain. This stretches and wears the chain and gears over time allowing it to jump a tooth once it gets bad enough. Replacement is the only option at that point. If you hear it, you'll swear something is broken. It's loud and very unnerving.