Well with much faith I took my 87 Soob on a road trip to montana from washington. On the way back I had the AT TEMP light come on. I was driving about 75 to 80 MPH ( 4500 RPM ) it came on it was about 90degrees in high desert. I stopped and checked the fluid level and it seemed a little low so I add a little and drove on where the light again came on when I hit 75. I again stopped for a bit and then drove at 65mph and it did not come back on for a while.

 

Was this due to the high temp and extended driving of a road trip or something else that is going onand can be addressed.

 

The light did not come on today on my 30mile trip at freeway speed into worl this AM

 

87 GL Wagon 4wd 3at

188K

 

Thanks for the imput

I'd say it's time for a trans flush. It does sound like what happened is excactly what should. The light came on when the fluid was too hot. The fluid may be getting hot because it is old and has lost some of it's hydrostatic nature.

you can get a heavy duty trans cooler at u-haul for about 40 bucks. super easy to install. every 10 degrees in temp rise reduces the life of the trans by half

+1 on the trans cooler, especially if you've got any weight in the car.

where is this AT temp light at?!?? I have never seen hide nor hair of it on my car; i can tell for SURE it isnt in the actual instrument cluster, is it down in the bank of red lights that has the CEL and the Brake Fluid warning light?

 

I read the subject and thought you had to be daft or something, but everyone else here seems to find it reasonable so *I* must be the loopy one.. (big shocker, huh guys? :-p)

where is this AT temp light at?!?? I have never seen hide nor hair of it on my car; i can tell for SURE it isnt in the actual instrument cluster, is it down in the bank of red lights that has the CEL and the Brake Fluid warning light?

 

Correct, that's where it is, left side off the steering wheel, by the charge light. It should come on when the key is turned to on before starting. Perhaps you're bulb is burned out. The sensor is a simple thermoswitch that completes a circuit to ground for that pin of the TCU, triggering the light.

 

Now something interseting is that the 2 wires for the ATF temp sensor are run inside a shielded caseing, which is connected to ground. If for some reason that cluster of wires get's to hot, the shielding will melt through the wires, and ground the circuit causing the AT TEMP light to come on. If you're AT TEMP light is always on, even at startup, chances are it is this or some other type of short to ground.

 

Note: for all you 4EAT owners. When AT TEMP light is on, the 4wd transfer is reduced to minimum(FWD only pretty much) at the same time, if the temp light is on, the TCU will keep the trans in *power* mode, utilizing higher shift points and will downshift more readily. So if you're sensor or wires are shorted you will be stuck in power mode, with no 4wd. Supposed to be a failsafe mode but LAME!!

 

87 GL Wagon 4wd 3at

188K

 

 

well, I figured that made enough sense, so I went back and re scanned the original post...

 

I repeat.. huh?

 

I mean, if its a 4EAT thing, then yah I don't have it.. but why does he?

It's a red light down in the cluster like was said previously, says "AT OIL TEMP"

 

+1 for a tranny cooler (And maybe a trans temp gauge... Wouldn't hurt, esp for long drives...)

I mean, if its a 4EAT thing, then yah I don't have it.. but why does he?

 

Both 3at and 4EAT have the AT TEMP light.

 

In the 3at it is just a warning to the user to not drive hard (or just stop for a bit)

 

In the 4EAT, when the temp is high(AT TEMP light on) it triggers the TCU to put the trans in *power* mode and to limit the 4wd transfer to nearly zero.

 

Slightly different function in either vehicle, that's why I put "Note: for all you 4EAT owners."

Both 3at and 4EAT have the AT TEMP light.

 

In the 3at it is just a warning to the user to not drive hard (or just stop for a bit)

 

In the 4EAT, when the temp is high(AT TEMP light on) it triggers the TCU to put the trans in *power* mode and to limit the 4wd transfer to nearly zero.

 

Slightly different function in either vehicle, that's why I put "Note: for all you 4EAT owners."

 

Where is this thermoswitch that powers it in the 3AT???

 

Im going out to my car now to look for this light. I thought I had categorized all the idiot lights in this car by now, but this is a new one on me.

Where is this thermoswitch that powers it in the 3AT???

 

I think it is on the drivers side near the rear of the trans