2004 v70 2.5t AWD temperature / transmission weirdness Topic is solved

Samitches · Post by **Samitches** » 04 Jun 2018, 20:12

So I have this 2004 V70 2.5t with the AW55-50 with 150k miles which I have recently bought.
It had rough shifting issues when getting up to temp, so I did multiple fluid flushes (along with a new radiator and flushes due to suspected cooling issues).

Now where I stand is that the car runs and shifts perfectly, with the AC fan running.
If I turn off the AC fan, the temperature rises to a point where the transmission shifts super rough.
Even idling, the engine fan does not come on even when the engine seems hot.

I've tested the fan through VIDA, and it will run at all the test power levels.
However, I did notice while watching it idle, the ECM was attempting to send an 8-9% fan level, and the fan was not running.
That percentage was not available on the Engine Fan test (the lowest being around 16%).
I also notice that my fan does not often run after i shut the car off, even in higher temperatures when I know the engine is very hot.

Any ideas on likely culprits? Coolant temp sensor?

Post by **abscate** » 05 Jun 2018, 04:30

Start up and turn AC on full. Does the fan come on? From here fault trace voltagesupply back from the fan To find where the voltage is interrupted.

Samitches · Post by **Samitches** » 05 Jun 2018, 04:55

Yes, the fan does come on with the AC. It's the only way that the fan seems to come on.

Post by **oragex** » 05 Jun 2018, 09:51

The transmission does indeed read the fluid temperature and adapts the shifting.

When the fan is off the fluid surely gets hotter, maybe the transmission then either reads the wrong temperature and sets the wrong shifting, either the fluid overheats and is loosing it's properties (less probable). I suspect you put in there the correct 3309 type?

Maybe an issue with the transmission temp sensor ?

As for the fan, on mine it seems it seldom kicks in (except when the ac is on), looks like this radiator does a great job. On the other side at 15 yers old the original coolant thermostat is surely stuck open

FREEBUSINESSES · Post by **FREEBUSINESSES** » 06 Jun 2019, 05:48

Given this is only post which states transmission weirdness, here is my question. I am getting message
TRANSMISSION OIL FIX NEXT SERVICE and for the life of me, researching every forum, only a few have posted this same message, but none posted an answer as to what needs to be fixed? Transmission appears to be working fine, nothing unusual, but I did notice when I acquired this XC70 that the fan would run after shutting down even when not warm weather condition? Temperature gage was no higher than middle of gage, seems to take longer to reach temperature, so appears to be on cooler side of scale and takes several miles to reach middle of gage, so could that set this strange message. No check engine or service lights other than this message.
Thanks,

Samitches · Post by **Samitches** » 06 Jun 2019, 11:32

I'm not sure on your issue, Freebusinesses. From my experience, the temp gauge will stay near middle even if things are getting too warm.

In my case, I was finally able to solve my rough shifting issues (due to overly hot transmission fluid) mostly by fixing another issue: cleaning the throttle body. After coming up to temperature, the car's idle would surge at stops. Continuously from about 800-1200rpm. My theory is that since the throttle plate was not able to fully close due to carbon buildup, the ecu would be forced to keep adding more fuel in small bursts to keep the a/f ratio right, causing the surging, but also causing extra heat, which would soak the radiator and make the transmission fluid overly hot.

Now, the shift flares and rough shifts / hanging shifts have been all but solved (just the slightest blip once every few drives). Not even another fluid change was needed after fixing the above problem. Hope this helps anyone having similar issues!