I drove the truck about 200 miles yesterday heading to the beach for the 4th of July celebrations and things got bad.

When I let off the gas and applied brakes approaching traffic around 70mph on the highway, I could feel and hear noises. It felt like a grinding. When I re-applied throttle, it went back to normal. So I got off the next exit and let off the gas again, applying the brakes and the grinding and noise came back and the Transferbox Neutral Warning Lamp came on with a chime. It staying on only for a few seconds.

I pulled over and searched underneath for signs of fluid leaks or anything to indicate that the transmission might have lost fluid, but I could not see anything. The drivshafts and "U-joint" connections all look OK.

When I got back on the road after a 5 minute rest, the truck did not make the noise again and the light has not come back on.

Where do I need to look first to diagnose this issue?? Is the transfer case fluid different from or does it share with the transmission??

Thanks for any help guys!

 

Not much to suggest with that warning lamp but I do know that the transfer box and the transmission have separate fluids so check that. If you haven't had them changed out in a while then shortly after you get home would be a good time. But check the levels and have them topped off until you get to where you can work on it yourself.

Also grinding around the 30ish mph levels and again at 70ish mph could be the front driveshaft. If you are running on the original one it might be time to replace and/or upgrade.

Mine made a grinding noise in those mph ranges but looked fine. I ordered a new one and when I replaced it the old one wouldn't rotate by hand once off of my disco. Not easy to spot unless it's hella bad on the vehicle but quite obvious once it was off.

Had something similar a year later with my rear driveshaft.

If you have the ability, try putting all four tires up on jack stands and spinning both driveshafts by hand. Or have someone spin a tire while you watch from below. You would be able to hear it/see it at that point.

 

Make sure the transfer case is positively engaged in high gear! Go inside and apply pressure to the shifter while the vehicle rolls slowly, like 5-8 Mph, in neutral.

 

Just ran it around the block and up to 65mph.. No noise or grinding feeling..

I shifted into Low Range and back to High without any alarming noise..

 

I drove home from the beach, 200 miles and the truck ran just fine. However, when I went for my first exit ramp to get food, the truck made a "clunking" feeling and the "Gears Dash Lamp" started flashing and chiming again.

I exited the interstate 3 times and every single time the truck makes a clunking noise and feel, and the dash light chimes and flashes.

Once I get back on the throttle, it all stops. I have just driven around town since returning home, and no noise or lamps.

What would cuase this issue during deceleration from highway speeds? This is the only time it happens...

 

Slack in drive shaft u joints, or slack in TC.

 

In your first post you said the transfer box neutral warning lamp came on and then in your latest your post you said the "gears dash lamp." Are you talking about the same lamp both times or two different lamps?

 

Same lamp, it looks like gears on the lamp.

 

I'm going to take the front driveshaft off today and check it out.. What am i looking for in particular??
I'm also going to watch a few videos as well..

 

Does it make a difference that I put a 1.5" spring lift and slightly larger tires on the truck about 2 years ago??

I didn't think that was enough to warrant getting a longer drive shaft.