The sensor on the trans cooler in front of the radiator are known to fail.
I had to replace mine years ago for the same warning light.

I remember them being pretty cheap.

 

Walmart Superteck ATF and/or Valvoline MaxLife ATF are fine to use.

On pre 03' D2s the trans light can be activated by either the trans heat sensor or transfer box heat sensor.
......

 

I'm not sure if all transfer boxes have temp sensors. Both the tcases I just bought had plugs in the main casing instead of the temp switch. (both '04 cases). I haven't checked my '02 case to see if it has a switch yet.

 

On abran's advise, I read through the Rave again. The temp switch was removed sometime through the '03 models. Maybe corresponding with the return of the diff lock? Your '02 prob has it.

It's wired parallel with the trans temp sensor on the cooler so as they said, if you get the light, it could be either one (or both).

 

Yep, my '02 has it. It's the switch directly above the exhaust pipe, oriented parallel to the rear cross member.

I wonder if I should wire up the switch with my new '04 case...? Seems like a nice thing to have. Why did LR remove it?

 

I was wondering if it was the sensor rather than the transmission itself, as the light comes on even when the engine is stone cold.

If it's in front of the radiator it probably got a pretty good bath in all that water.

I'll probably replace the sensor and change the ATF just to be sure.

 

With the water, silt, mud, debris also check the radiator and tran cooler fins are clean

 

Finally got time to change the fluids yesterday.

Front diff - plenty of old oil but changed anyway - easy job
Rear diff - plenty of old oil but changed anyway - easy job
Transmission - plenty of ATF and water free but changed anyway ad changed the filter while I was at it - easy job
Transfer case - about a pint of oily water and not much else!!

Trying to figure out how to remove the filler plug on the transfer case on my driveway without the assistance of my 4-foot length of steel gas pipe. Can't get much purchase on the plug because of the flywheel shaped thing right behind the transfer case (the parking brake? not sure, please enlighten) and because the plug is at precisely the wrong angle for that four foot length of pipe to come into play without a hole in the driveway to swing it in.

Figure I can put the front wheels on ramps and pump in as much gear oil as I can through the drain hole, put my finger over the hole while I find the plug, then take the car to a nearby mechanic with a car lift to finish the job.

If anyone has any tips please post 'em up quick!!

 

It helps if you release the P-Brake. This lets the brake cable flex out of the way enough to get a wrench in there. It's still tight but I am able to get the plug out without removing the drum.

 

Use a 1/2 inch wiggle socket adaptor, it's a hard plug to loosen sometimes, that's why you loosen it b4 drain plug, if that failed, take out the sensor on top of T-case and fill from there as last resort, fill exactly 2,2 quarts gear oil, (not more or less)