While doing the brakes on my 99 Grand Cherokee Laredo, I noticed this hose hanging down on the driver's side, kinda near the differential. It looks a little chewed up on the end. I looked around a bit, but couldn't see anything disconnected or anything like that. I traced it up into the engine compartment, and there is a clip holding it onto the top shock bolt. There is also a green plug in the end of the hose..... What is this thing?? I'd post a picture, but I can't do it from work.

 

Probably the vent tube for front differential. Should be a port on the diff housing for it.

 

Its the diff vent tube.

 

I dont know on the 99-up but the ZJ's diff vent line snapped into clips on the lower part of the air filter box. You can put it where ever, or replace the hose with a longer one. You want that vent hose to go as high as possible and be shielded on the end so dirt/debris and water cant go down the tube.

 

Thank you. I will look for the connection.

 

if you've had it in water of any depth I'd check the diff fluid for water and change it if is looks sludgy