Used my AP200 to monitor ATF temps on a long hot drive in the mountains (heavily loaded but not towing)

In normal highway driving, the ATF stays pretty close to coolant temps (no more than 5*C > coolant).

Below 100* F air temp, it was pretty much the same, got a little hotter than the coolant above 100*F.

This makes sense, the tranny should be mostly locked up so the fluid isn't working hard.

Driving slow up windy mountain roads is where it got hotter, makes sense too since the tranny is shifting a lot and working the fluid, and there's less air flow. Maybe up to 10*C hotter than the coolant.


Interwebs says to keep your ATF no more than 225-250*F (107 -121*C).

So assuming that ATF might be 10*C hotter than coolant, you should be fine with coolant temps up to 100*C sustained, or 105*C for a while when climbing hills. If you get to 105*C, probably want to back off and let the temp come down a bit.

I'll update this next time I tow in hot/high conditions, that should be interesting.

 

Also I could not find actual coolant temp on the AP200, had to switch between that and my OBDII dash gauge to compare coolant and ATF temps. Awkward. Obviously OBDII has a coolant temp output.

Anybody know where the coolant temp is on the AP200 interface?


The ATF temp can be found in two places...

Under the ECM module, it's listed as "transmission oil temp".

Also listed under the TCM as "oil temp". It's a lot easier to find under TCM.

 

Cant answer where to find the coolant temp on the AP200 but my transmission temp seems to run about as you noted. My trans needs to be rebuilt as it freewheels then slams into 3rd when it gets hot. Monitored the temps with my AP200 and it was OK up to about 170F. Higher that that that trans misbehaves. Hottest I noted was 195F going up a long gradual hill.

 

Before you tackle a rebuilt tranny, this 6 speed Aisin always responds well to a transmission fluid change/flush with the OEM fluid. I used synthetic for a year and did not like it so I went back to the Aisin OEM fluid avail at Rockauto. In addition, Volvo shares the same si6 (it's a Volvo engine built by FoMoCo) and the same 6 speed Aisin transmission on certain models that came with the si6 around the same year class. There are also YouTube vids to do a full flush and the correct way to set the level at the end.

 

Yes, I tried the fluid replacement. It didn’t really help. There is a seal or piston that is worn out. Just wound up with other problems with the “steering column locked” message and no start. Not a good beginning. This poor car was extremely neglected and goes to show you cant trust carfax or car dealers.