AT Oil Temp Light
 

Hey, I know this is is a question that has been asked before. But I am currently with my truck in Guetamala so have the added difficulty of language/no tools.

We have driven from LA with no problems, 70mph for 8 hour days on same days. Recently on a long hilly section the at Oil Temp light came on. We stopped put it in park and left it for a while. No change.... we were running out of fuel so turned it off and back on. Light is now off. We drove another 20 minutes light back on repeated the process.

After filling up with gas we have not had the light again, although it was not a steep and incline. Less load.

Any suggestions of what we should do? would like to have a fair idea of what is going on before going to a mechanic here as will be difficult with language and also wary of being ripped off.

Cheers

It's funny, i had the same issue a couple of weeks ago. What made mine even more strange is it wasn't a hot day and it was a drive I had done several times with no issue. Also, light hasn't been on since.m good luck.

I'll ask the obvious question.....how does the fluid look? Does it look fresh and smell okay or is it dark and burnt smelling? When going up hills or starting off from a dead stop does the tranny slip at all?

Did you change the fluid as part of the bullet-proofing process before venturing thousands of miles into drug cartel and kidnapping-for-ransom land? I'm guessing maybe not because learning some spanglish might have been up there near the top on my prep list.

http://www.pirate4x4.com/forum/toyot...sues-faqs.html

Best article I've ever read on the a340h chain drive. Post #2 will explain exactly what the problem is and how to remedy it.

If you drive at just the right highway speed on a hill, the transmission can come out of lock up (you can feel it unlock, and the rpm will jump a bit). Usually, slowing down a tad will reduce the load on the transmission and it will go back into lock up. But if you're driving 70mph up a long hill (from SF to Lake Tahoe, for me) with cruise control, you may not notice it (or you may not pay attention to it), and you can end up driving for a while out of lock up. This will heat up the transmission and switch on the Temp Light. This happened to me twice, with air-temps well below freezing both times.

Each time, I just stopped for 10 minutes, and on restarting the light was gone. I suspect that the light turns on with over-temp and stays on even if the transmission cools, until you cycle it off and on.

If that's your problem, don't use the cruise control on long hills. When it comes out of lockup, ease off the gas. Heck, don't try holding it at 70; you'll use 10% more gas than at 62mph or so.

You may also want to check your fluid level. It’s very easyto overfill this transmission, which can result in overheating.

There is a very narrow temperature range the transmissionhas to be in for an accurate dipstick reading (can’t remember offhand but it’sin the service manual).
I use an inferred thermometer aimed at the pan to see if it’sin range.

I recently added an aftermarket transmission cooler (inaddition to the one built into the radiator). I figured that in my hot climate,it’s sure not going to hurt.

do a trans cooler. a big stacked plate design. cant run it too cool. warmer it gets....the faster trans fluis goes bad.

heat kills autos. make it cooler.

I'll second an aux cooler. I was running stock 31x10.5s at 70 for 4 hours at a time and I'd almost always have the A/T light come on. It wasn't until I started going 65 that it quit. It does have to do with the lockup. Anyway, the fluid was always bright red and never had any damage I was aware of from it happening probably 12-20 times within a year. You might want to do a few drain a fills on your trans during your next few oil changes just to be safe.

Hey guys thanks for the responses.

We had all the fluid levels checked when we left Los Angeles.

We have not noticed any problems with the transmission at all. It starts fine. Does not seem to slip and we rarely use cruise control.

The roads down here dont allow for it.

Only have the problem when going up long prolonged hills.

So..... thinking a change or a flush then? just don´t want to risk doing more damage to the transmission as this is a hilly country and dont really want to risk it.

Cheers

Was the fluid level checked at the proper temp range? If not (and most shops are not taking the time to do this), then your levels may be off.

It may not be the cuase of your issues, but it's worth taking the time to ensure the level is correct.