Drain And Fill Tranny Fluid 2nd Gen Tacoma

I have changed my tranny fluid in the past by simply measuring the amount coming out and put that same amount back in. Recently I have seen numerous video's on how to do this utilizing the AT/Temp Light. According to the THECARECARENUT web page, the following is how to do it:
(1) after filling, inner connect OBD II terminal 4 on the top row and 5 on the bottom row. (2) Start the vehicle and shift through all the gears a couple of times and then rapid shift drive/neutral until the AT Temp light flashes once and it will go off. (3) Put the vehicle in park and pull out whatever you used to inner connect terminal 4 top row and 5 on the bottom row.
(4) Just let the vehicle idle until the AT/Temp light reappears and then just pull the overflow plug until the fluid is merely a tripple. If the AT/Temp light flashes, the tranny is too hot to check the fluid level. I test this procedure with the AT/Temp light today from a cold start. I disconnect the inner connections on the OBD II connector once the light came on, put the vehicle in park and within 2 minutes the light reappear and stayed on for well over 5 minutes. The light never did flash over the 5 minute period indicating again that it was too hot to check. Any thoughts? Again my truck is the very first year of the 2nd Gen.

 

Ambient temp. always gives people problems. What was yours before you started?

 

Try this

 

I use a Scangauge II for trans temps.

 

Don’t touch it, not necessary…

 

not recommended

 

I hate to ask.....but has anyone tried taking a measured amount of the WS fluid and deliberately looking at its volume change when temperature is accurately varied? I once worked in a lab that could easily and accurately do this - but not today. If the factory volume check is at 98-115ºF - and the trans is typically at the shared radiator circulation temp of say 186º F - what is the volume gain (or rather - loss at the lower temp?).

There could also be a volume gain in space due to the thermal expansion of the case. It would not be linear - more like the volumetric expansion of an aluminum cube. I understand that the practical factory test method takes all of the variables into direct effect with a single measurement - but why would it vary enough to be unpredictable? Seems like an unnecessary complication of something that was always done with a dipstick - but of course - this eliminates the cost of the dipstick ........

 

Yes, when it’s hotter it displaces more fluid.
Toyota actually had a hot temp check tool that extends the check plug drain to compensate for higher temps.

It’s why when I adjust fluid at the high end of the range I plug the check bolt sooner.