I just got a call from son from Chicago. His wife's transmission (auto) high temp light lit up on her 2000 4Runner w/3.4. He searched this site and found 'tons of info on external coolers...not what he was looking for. She experienced the 'strawberry milkshake' several months ago and went through the tranny flush/NEW radiator to remedy the problem. I'd posted pics of the pink shake dripping from the rad hose to inform readers that the mixture didn't have to mean blown head gasket but also tranny cooler failure when mt goat educated me about THIS common problem. Now the high temp light is on. My son would like to have a better idea as to why. Will an OBD II scanner point to the problem? Could it be a faulty temp sensor for the tranny (location of sensor if there is one???)) and is it testable or is the rad crapping out again? Thanks for any and all help.

 

If you did the flush and clean of the tranny as well as replaced the radiator, your issue now is the transmission is going. It would be worth a trip to a reputable transmission shop to have it "serviced". Ususally runs around $100 to have it drained, pan removed, inspected, new filter screen and by looking in the pan they can tell if the tranny is going to need to be replaced/rebuilt. The problem with the strawberry milkshake is you are most likely going to need to rebuild/replace the tranny. It is not a given hard and fast rule but depending on how long the tranny was bathed in the coolant/ATF mix will determine when the clutches and bands deteriate and to what extent the damage was done when it happened. If the A/T light came on that usually means the ATF is cooked (305 degrees is not good) Check the fluid, brown, burnt smell does not bode well. Have it checked, and go from there. good luck

 

Possibly, it would tell you the coolant temps. If the coolant temps are also high maybe the fan clutch has gone out. Can't really tell much by looking at the dash temp gauge because they are designed to stay in the middle through a big range of temps.

Assuming the ATF temp sensor is good, it does point to a serious issue unless the wife was towing a heavy load uphill or something.

 

Shot in the dark here....

When x-fer is in Neutral position, and tranny is in P, the light comes on (I think it means that there is no hydraulic fluid flow through the cooler, so not good to leave it there). Maybe the switch for this circuit is faulty? Try "exercising" this feature by shifting transfer through all positions while in P (and briefly put transmission in D with transfer in N - note, shift tranny from D to N to move transfer back to L or H, not park it won't go, at least not nicely).

 

Is the fluid full? My 93 did it and we switched to synthetic and added a large cooler.