This came on yesterday while I was in town. I pulled over and put it in park and let it idle for about 10 minutes but the light didn't go off. I decided to get lunch, do some shopping and let it sit for an hour. Started it up and as soon as I put it into drive, the tranny light came on again. I drove it home and checked the fluid level and it was full. I went ahead and changed the fluid since I don't know when it was last done. The fluid was a bit dark but didn't smell burned. I filled it back up (yes, I read the "how to" and did it right) and went for a drive. 5 miles and the light came on. Even with the fan clutch engaged all the time AND the heater running on high (uggh!!) windows down of course, the light was still on. This was going down a county road at 40mph, fairly level, and no stops. I'm thinking bad temp sensor (?) but reluctant to drive it until I find out. Will a scan gauge show trans temp? AB doesn't show a trans temp sensor so don't know what they cost and don't care to buy parts I don't need.

Eric

 

scan gauge does show transmission temp but I wouldnt trust it to tell you on a discovery.

It scares me that its not coming on instantly which would mean it was a dirty sensor. However I wont rule that out. If you want to save a little money and have a little time. Clean the sensors. On a D1 there on the tranmission coolant line at the front drivers side and the other is on the transfercase.

 

Ahh, i've got the same problem. It came on in mine yesterday...let it sit for a couple hours, checked it again and still on. These things run and get pretty hot so I let it sit through the night and its still on.

Mine comes on immediately after all dash lights go out, it pops back on. Does that mean my sensor is bad? Because it definitely couldn't still be hot, even in the FL summer. Should I check the trans fluid level? I don't know of any way to check it without draining it since my DII isn't fitted with a trans dipstick.

Any help is appreciated.

 

So since my original post, here's what I've done: drained the fluid and filled, drained the fluid, replaced filter, and filled. Temp light still comes on after 5 miles of driving. Doesn't matter if I start it up and go or start it up and let it idle for half an hour and drive. 5 miles and the light comes on. Today I checked the fluid temp after it came on. Using a digital thermometer, I checked the fluid at the fill plug and it was 168 degrees. On the return line it was 136. Google search (for what it's worth) says that temps above 200 will severely shorten the tranny life and "normal" is 150-175. After I checked the temps, I sprayed the front grill area with my garden hose for about 15 minutes. Temp light still on!! I'm thinking bad sensor.......

Eric

 

Where was I when this post came up back in Aug?
You need a new trans temp sensor.
Common fail point on DII's.

 

Read the Rave manual and it looks like I have to remove the cooler to get the temp sensor out. (Really?) If so, should I have the cooler flushed as long as it's out? Where's a good place to get the sensor? (AB doesn't show it)

Eric

 

http://www.roverparts.com/Parts/UBI100030G.cfm

 

Thanks Spike. When I searched, it just kept showing the trans cooler.

Eric

 

Be sure to ignore the rave on how to replace it, it wants you to dismantle the entire front end of the Disco. DO a search, the easy way is to go in through the right front wheelwell. Will only take you about 20 minutes including, removing and replacing the tires

 

Thanks! Did some searching and found the shortcut you mentioned. That sensor was in there tight!! Looked like a "factory original" (all corroded) Put the new one in, topped off fluid and went for a drive. No temp light!! Now I can finally put some miles on this thing. (Was reluctant to drive it incase there really was a problem)

Eric