Service 4wd message

[Slade8200]

The '06 I'm looking at, with 155k, has a "Service 4wd" message on the dash. I've done a lot of searching on this and it seems that the vast majority of the time it's either the dash switch, control module, or the encoder motor (I don't know the status of the switch lights, or if the vehicle goes into 4wd). That switch and motor are both relatively cheap fixes which is fine for me. But what are the chances it's a serious mechanical issue that's going to cause me to need a whole new transfer case?

Thanks.

[kstruckcountry]

If the transfer case doesn't make noise bad when it's driven, it's probably not too serious. The pump rub issue can cause more serious issues if it isn't looked after.

 

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[Slade8200]

What causes the pump issue? Low fluid?

[06pirate]

The issue is the oil pump eats through the case, and pumps the oil overboard.

 

My '06 Sierra ate the transfer case because the oil pump wore a hole into the outer case and the oil pumped out a little at a time until it destroyed it. I didn't notice the oil seepage soon enough. I had the warning lights but neglected to get it scanned until it gave up the ghost. It made a loud squealing noise one day going to work, and on the way home, it somehow shifted itself into low range and that was all she wrote. The mechanic showed me the black burned sludge that came out of it and it was fiull of ground up metal. Nothing repairable, so had to replace the whole thing.

[Slade8200]

Sucks. But what actually causes it? Faulty mfg?