I have a 99 Disco II with 107k on it. Recently the trans Light has been coming on - Just me in the vehicle, so I'm not pulling a load or anything heavy - it comes on after about 15-20 minutes on the highway.....if I let it sit it'sll go off....any idea whta is causing the transmission to heat up?

 

First things first, check the trans fluid level.
If you are not sure how to do that there is a how to in the tech section.
If the trans fluid is full and clean then replace the trans temp sensor, it is a common fail item.

 

When did you last service the tranny and or check the fluid level?

 

embarrassed to say 5 years ago

 

crawl up under the truck and unwrench the fill bolt out and stick your finger in there. Not when the engine (fluid) is too hot or it will burn ya.

What's the fluid look like? What's it smell like?

 

so I replaced the transmission fluid and no more light - the fluid in there actually looked ok and smelled normal............so thank you for the advice - the change seemed to do the trick......

 

Good deal, that you for reporting back.

 

ARRRRRRRGH - it came back on again - I guess I need to try changing the temp sensor - does anyone know the part number? Also Just as a side note the light comes on after driving about 8-10 miles or so and if I let it sit for 5 minutes it will go off and come on again after driving a bit (so it isn't in a constant on mode - not sure if that points to something different then the sensor)


One other symptom to consider is that since we changed the trany fluid - it takes significantly more time for the light to come on.....ie the light came on withing 2 miles now it takes about 10 miles - it seems like something is causing it to heat up - also there are no OBD II Codes thrown....any ideas?

 

I replied to your PM.
I would replace the temp sending unit and then go from there.
Eliminate the cheap/free/easy stuff first.
Unless the trans cooler is clogged there is no reason for it to overheat while just driving normal.

 

So do the disco II's have an oil pump for the transmission fluid that could have gone bad that may be the problem....