What temp does the A/T oil light kick on? (1 Viewer)

[Brian894X4]

Seems like I've read this in my numerous past searches and I searched forever to find it again. I've only found one single mention and that was someone talking about the spec for the 440, surmising that it was the same for the 442, being A/T light kicks on at 302F and kicks back off at 248F

I have the 343 and my FSM doesn't mention this anywhere. It only mentions testing the temp sensor at 68F and 230F.

It does mention normal operation temps as 158-176F (122-176F on some pages for certain tests).

I did find this article regarding the mini-truck transmissions, which seems say that their A/T light kicks on 284F.
http://www.gearsmagazine.com/images/issues/4_2006/2006_04_35.pdf

Anyone have a concrete spec on the '95+ A/T oil light kick on temp?

 

[Cruiser Jimmy]

just researched the 442 and it's the same as the 440. I think I have the 343 tranny manual at home. I can check for ya.

 

[Brian894X4]

just researched the 442 and it's the same as the 440. I think I have the 343 tranny manual at home. I can check for ya.

Thanks much! If you can find out if its the same I'd really appreciate it. MoGas over on Expo posted this for me about the 440/442.

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I referenced my library, and according to my 91 FSM (A440F): 302F on/248F off, 93 FSM (A442F): 302F on/ 248F off, 94 FSM (A442F): 302F on/ 248 F off.
Dave (MoGas)

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By the way, I have a '95 FSM, but I can't find this spec anywhere in it. At least in the tranny section. Am I just missing it?

 

[e9999]

wow, these temps are pretty high. When I am plowing through sand in Hi, I don't go above 200F or so. When I switch to Lo it goes back down to 180F.

 

[Cruiser Jimmy]

You're looking at the vehicle FSM right?

I just looked at the tranny FSM for the 343. I did not see any reference for temp range, which is inconsistent with the prior two tranny FSM's. The 'operations' section of the FSM for the 440 and 442 have the temp ranges but the 343 does not.
However, IMHO I think the physics are still the same and you should be able to use this as a reference.

 

[Cruiser Jimmy]

wow, these temps are pretty high. When I am plowing through sand in Hi, I don't go above 200F or so. When I switch to Lo it goes back down to 180F.

Thanks, rub it in.


What kind of gage are you running and what's the location of the sending(pickup) unit.

 

[Brian894X4]

I was trying to figure out why the huge difference between "normal" temps and "idiot light" temp. Over 120 degree difference.

The only thing I can think of is that the transmission can run at the mid to upper 200 degrees, and in some cases, such as towing without the optional cooler (like a country that didn't come with them) or extreme desert temps, etc, maybe the transmission does see regular temps in the low to mid 200 range, but for normal driving on the highways, mid to upper 100s is normal, especially with the cooler.

You don't want the light coming on, unless the tranny really is exceeding its design parameters, because telling someone to pull over or stop when they don't have to, can cause huge issues. It can cause an accident, cause someone to get stuck, etc, so that's probably why the temp is so high.

Which is why a guage would be nice to have, because you see that problem is brewing before it gets that bad.

 

[sdbrassfield]

302 degrees...Yikes...I would think the tranny would be definitely cooked by then...Most engines would would be smoked by then ...

 

[Cruiser Jimmy]

I see your question. I think the light comes on before you start to cook the seals, boil and evaporate all the ATF. You can still drive the vehicle in the mid/upper 200's although you'll breakdown the ATF more quickly but the clutches should get'cha to a shop before the ATF is gaseous, last resort mind you.

I have an Autometer trans temp gauge on the tranny to give me actual temps. Ideally you want to see the temps coming out or going back in the tranny to see the heat being generated or cooling effect respectively.

There are two areas were hot is generated. The clutches and the lockup. Both are catastrophic if allow to overheat. I should know

 

[Blasphemy]

Whats the part number for the switch for 100 series a442?