So yeah, when it's warmer outside (50 degrees or above it seems) and I drive my Disco on the highway at anywhere from 60-70mph for about 20 miles my transmission temperature warning light will come on as I leave the highway and start to slow back down.

However, just to experiment I got back onto the highway and drove for about a mile and the light went back off.



Also, unless I'm driving at a higher rate of speed for a while the light never seems to come on. I can off road for hours in the same temperature, drive around town even and the light will never come on unless I get onto the highway and do what I stated above.

It's not low on fluid, the fluid is not dirty, it's not the transmission filter, and the temperature sensor is not bad.

Faulty, or clogged transmission cooler perhaps? What about the electric fan on the passenger side located in front of them? Does it half a hi/lo setting and maybe the high setting isn't working?

 

Take it to a shop!

Ok, sorry, I could not resist. Please dont hate me,ok, you can if you want too.
I would lean towards a bad trans oil cooler.
The fan behind the grill is the A/C fan and aux engine cooling fan.
It comes on when the A/C compressor kicks in or when the engine is about to overheat.
This fan could be bad, repeated driving through deep water and water gets into the electric motor and the bearings go bad.
Happened to me on my Montero.

 

Lmao.....



Well the fan works, or at least it spins and such because that was the first think I thought to check when I stopped, but I was just wondering if it had hi/lo setting and perhaps it was stuck on low and wasn't flowing enough air.

But I'm definitely leaning toward the cooler just being bad really.

 

I do not know if the DII electric fan is a two speed fan or not.
I know that it is not on a DI, but a DII I do not know.
It does run though? Or have you just spun it by hand?

 

How do you know the trans temp sensor is not bad ?

They are known to go "iffy". I recently changed mine for that very reason. Also "if" you go offroad in muddy water etc, then its DEF worth checking thecooler for clogging. Mine was about 30% clogged up. It already has a hard time cooling as its behind the aircon rad, so a small amount of clogging will affect its performance for sure.

Im still wondering why the D2 hasa trans temp warningand the D1 dont, I cant see the trans oil temps being "that" different between the 2 trucks tbh

 

I think the DII has a tran temp warning because it is a electronic trans and the DI is a mechanic trans.
And Iif I remember right the DI has a larger trans cooler than the DII.

He has already replaced his trans temp sensor.

 

Yeah, temp sensor is brand new. Fan works as well, it was running on it's own when I checked it. It's very likely my trans cooler is either done for, or just clogged up since I have done some hellacious things in the water with it.

 

The trans cooler on my D2 is bigger than my D1, well its totally diff tbh, the D1 is a tube with a "hairy" type cooling matrix, the D2 is just like a small radiator, but its full width and about 4-5" high.

I missed the fact you had replaced the switch, then its either clogged or time for an boxoil change.

 

Well, to know for sure, you need to find a shop with a scanner that plug into your"Funky" tranny and see what the actual run temp is. Either the temp switch or the tranny or failing.

 

I did not know that.
Thank you for setting me straight.