PSA re: 4th Gen A/T OIL TEMP Light Trigger Temp

[Bluesky 07]

Always wondered what temperature would trigger the A/T OIL TEMP light. Apparently it's 302° F. Found this in the FSM while doing research for a response in another thread.

Interestingly, this chart was in a doc that's there for the A750E transmission in trucks with the 1GR V6. There was no corresponding doc for the A750F transmission in V6 trucks, but my assumption is that the info is the same or close enough to be an insignificant difference. Other opinions welcome about that.

Note there's a typo in the top "Detection Condition" box; 150° C is 302° F, not 275°. The other conversions are all correct.

 

[xtremewlr]

Always wondered what temperature would trigger the A/T OIL TEMP light. Apparently it's 302° F. Found this in the FSM while doing research for a response in another thread.

Interestingly, this chart was in a doc that's there for the A750E transmission in trucks with the 1GR V6. There was no corresponding doc for the A750F transmission in V6 trucks, but my assumption is that the info is the same or close enough to be an insignificant difference. Other opinions welcome about that.

Note there's a typo in the top "Detection Condition" box; 150° C is 302° F, not 275°. The other conversions are all correct.

Um, WOW! By that temp, I would call the transmission toast! Makes me glad I upgraded my already upgraded trans cooler recently.

 

[Bluesky 07]

Um, WOW! By that temp, I would call the transmission toast! Makes me glad I upgraded my already upgraded trans cooler recently.

But doesn't the "Recovery Condition" parameter imply that under 275° F is a safe operating temp? Seems way too high as you say but why else that would turn off the light?

 

[xtremewlr]

But doesn't the "Recovery Condition" parameter imply that under 275° F is a safe operating temp? Seems way too high as you say but why else that would turn off the light?

Google search say this: "The ideal operating temperature for automatic transmission fluid is between 175 and 225° F. At approximately 240° F, important additives in the ATF begin to cook."

I'm not comfortable with having the transmission get over 200 as it is.

 

[Bluesky 07]

Google search say this: "The ideal operating temperature for automatic transmission fluid is between 175 and 225° F. At approximately 240° F, important additives in the ATF begin to cook."

I'm not comfortable with having the transmission get over 200 as it is.

But the fluid is WORLD STANDARD!! LOL

Seriously, you make a valid point. Toyota seems to have set it way too high. Wish we could know their reasoning.

 

[xtremewlr]

I just don't depend on the warning light to know if it's getting too hot. I set my UltraGuage up to monitor trans temps, so I actually know where it's running at. Most of the time, with normal commuting/driving, it stays under 200, in the 170ish range. With the larger cooler I installed, it takes much longer to get to those temps.

 

[Zero0575]

I had the light come on during a recent trip, about 500 miles from home. It came on close to my destination, and was only on for a couple minutes.

My trans still shifts fine. I changed the fan clutch before heading back home, and did a fluid change once home. Also added an additional aux cooler.

Anecdotal, I know, but my point is the trans isn't necessarily immediately 'toast' once the light comes on. But this also might matter...I do a pan drain/fill every 15-30k miles. So even after reaching those Temps, when I got home and changed the fluid it was still very red and didn't look burnt.

 

[Bluesky 07]

I just don't depend on the warning light to know if it's getting too hot. I set my UltraGuage up to monitor trans temps, so I actually know where it's running at. Most of the time, with normal commuting/driving, it stays under 200, in the 170ish range. With the larger cooler I installed, it takes much longer to get to those temps.

Nor do I, I have an OBD reader and the OBD Fusion app, and an external cooler with a bypass that excludes the cooler until the temp exceeds 180F. The whole light thing came up when I was responding in another thread in which someone was worried that their temp read 235F with a thermal device. Their light never came on and thinking about that just made me curious what the trigger temp is so I researched it.

 

[xtremewlr]

I had the light come on during a recent trip, about 500 miles from home. It came on close to my destination, and was only on for a couple minutes.

My trans still shifts fine. I changed the fan clutch before heading back home, and did a fluid change once home. Also added an additional aux cooler.

Anecdotal, I know, but my point is the trans isn't necessarily immediately 'toast' once the light comes on. But this also might matter...I do a pan drain/fill every 15-30k miles. So even after reaching those Temps, when I got home and changed the fluid it was still very red and didn't look burnt.

Yeah, my fluid change interval is at the 30k mark for the trans fluid too. I'm doing a change this weekend in fact and installing a PML deep pan while I'm at it. 2 additional quarts of trans fluid and thick aluminum casting so it will help keep the temps lower and more consistent, or so I hope.

Short bursts of high temp like that won't hurt the transmission, as you said. It's when they are sustained temps that high heat becomes a real problem.

Nor do I, I have an OBD reader and the OBD Fusion app, and an external cooler with a bypass that excludes the cooler until the temp exceeds 180F. The whole light thing came up when I was responding in another thread in which someone was worried that their temp read 235F with a thermal device. Their light never came on and thinking about that just made me curious what the trigger temp is so I researched it.

It's definitely worthy research and good knowledge to have in your back pocket for if something happens. 235 seems high to me and is slightly high according to what I found on Google. But if it only hits temps like that for a few minutes, then the trans should be able to survive without too much worry. I'd still plan a fluid change ASAP after hitting those higher temps.