Hi all,

New to the forum, as I recently acquired a 91 Montero LS (~230,000 miles). Been doing general maintenance to create a baseline. Everything feels good aside from the old vehicle squeaks.

Scenario: I took it for a cruise on the highway, 65mph-70mph for about 30 mins. Drives great. Going up a bigger hill, I noticed it feeling sluggish and not accelerating like it was, soon after the A/T Temp light came on the dash. I pulled into an auto store to feel the trans pan/ let it cool/ and check the fluid level. It seemed like the fluid was very low (checked while idling). Put some oil in and drove back cautiously without issue aside from the light staying on.

The next morning, cold start, and light is still on (so not an accurate temp reading)... I did a trans oil change to get more clean fluid in. What came out was dirty but not black or burnt.

I've read several articles about the AT temps sensors on these getting stuck on. But basically just curious if there is anything else I should be checking so I don't grenade a transmission while I try to find a replacement sensor (seems like they only exist in japan). Shifts and drives smooth.

I'm also considering replacing the OG oil cooler and installing an inline temp gauge to monitor.

Thanks!

 

Try to replace the temp sensor. I think it's inside the pan. That means you'll probably have to dump all the new fluid

 

Thanks for the response! To my understanding, the AT temp switch is external on the cooler sender line and seems to be a common occurrence in Gen 1's that it sticks on. It also doesn't seem like any OEM replacement sensors are left in the US (some in Japan).

Since my first post, I brought it to a mechanic (friend) who checked out the entire transmission system, I put in a new accessory blower, and I also installed an inline temp gauge on the return line to make sure the oil cooler is operating. Bringing the trans to operating temp, it sits at around 160 degrees. So mechanically, everything is operating as it should, even though the AT Temp light is still on in the dash.

The only other concern now is that it isn't shifting into overdrive (4th) regardless if the button is clicked. So figuring out if it is a relay issue caused by the AT Temp switch being triggered.