2015 Silverado 6.2l Low Trans Temp

[Bryn7471]

Long time guest but my first time posting.  I bought a used 2015 Silverado 6.2l High Country with 33,000 miles on it back in March of this year. I started noticing that my trans temp rarely gets above 130-140 degrees.  Actually this morning I noticed that it was 80* outside when I started my truck but my transmission temp was only 67*.  Im not sure if it relates to my vibration I get randomly.  My truck will out of the blue with out correlation to speed or in v8 or v4 mode just randomly vibrate until I give it gas or back off. 

[Jon A]

It sounds like the original owner bypassed the thermostat.  I don't see how that could be related to any sort of vibration.

[Bryn7471]

[Bryn7471]

My only reason for thinking it might be related is because I was thinking the truck thinks the transmission is cold and adjust accordingly (shift pressures, etc).  I know some people have also had issues with the torque converter. 

[Lgetz]

Quite possible your vibration is an issue with the torque converter.   Mine went out and was replaced under warranty.  Feels like a slight vibration on your steering wheel.  Mine was initially happening only at 50-55mph but as it got worse all speeds were affected.

[truckguy82]

Thats a new one

 

yeah definitey something wrong if it’s 80 degrees out and your trans temp is 59

[truckguy82]

Just thought of a way to test if the temp reading is wrong. So assuming this part was not modified.

 

The trans thermostat does not allow much fluid to the trans cooler until it opens up at 190 degrees. So what you can do to test this, is go for a 10 minute drive and touch the return line from the transcooler. You can feel it by popping your hood, it's on the passenger side of the trans cooler.

 

That particular line does not get hot until the trans thermostat opens open. It will basically be ambient engine bay temp until then, and then scorching hot after. It takes a solid 20 minutes for a trans to get to operating temp.

 

So what you can do is

a) feel that line after 10 minutes, if that line is cool, you just verified that your trans thermostat is still installed because it's not allowing flow.

b)feel that line after 30-40 minutes, when you know for a fact that transmission is up to temperature.

 

if
A= cool line    and      B = hot line

you know for a fact you have a trans thermostat installed, that your transmission temp is actually reaching 190 degrees, and that your sensor is incorrect

 

 

<had a failed trans thermostat that would never open, this is how I could tell if it was working or not, by feeling that line.

(note, the trans thermostat does allow a very small amount of flow regardless of trans temp. It's enough flow to make the input line to the trans cooler hot, but the flow is so slow that it's ambient at exit. Once the trans thermostat opens up, it's hot on both sides)

[BigBadSierra]

Check and see if the previous owner changed out the factory Trans cooler. 

 

If they put a larger one on then that's correct. 

[truckguy82]

1 minute ago, BigBadSierra said:

Check and see if the previous owner changed out the factory Trans cooler. 

 

If they put a larger one on then that's correct. 

what terrible advice

his trans temp is 59 degrees on an 80 degree day

a trans cooler wouldn't change the temp unless the trans thermostat was changed

[Bryn7471]

25 minutes ago, truckguy82 said:

Just thought of a way to test if the temp reading is wrong. So assuming this part was not modified.

 

The trans thermostat does not allow much fluid to the trans cooler until it opens up at 190 degrees. So what you can do to test this, is go for a 10 minute drive and touch the return line from the transcooler. You can feel it by popping your hood, it's on the passenger side of the trans cooler.

 

That particular line does not get hot until the trans thermostat opens open. It will basically be ambient engine bay temp until then, and then scorching hot after. It takes a solid 20 minutes for a trans to get to operating temp.

 

So what you can do is

a) feel that line after 10 minutes, if that line is cool, you just verified that your trans thermostat is still installed because it's not allowing flow.

b)feel that line after 30-40 minutes, when you know for a fact that transmission is up to temperature.

 

if
A= cool line    and      B = hot line

you know for a fact you have a trans thermostat installed, that your transmission temp is actually reaching 190 degrees, and that your sensor is incorrect

 

 

<had a failed trans thermostat that would never open, this is how I could tell if it was working or not, by feeling that line.

(note, the trans thermostat does allow a very small amount of flow regardless of trans temp. It's enough flow to make the input line to the trans cooler hot, but the flow is so slow that it's ambient at exit. Once the trans thermostat opens up, it's hot on both sides)

Good idea.  I will try that after work today.  It drives me nuts because I don’t wanna mess my transmission up with it overheating and the truck doesn’t even know it’s overheating.  

[Jon A]

I would not be too concerned about temps taken at startup in the morning--it's showing you the trans cooled overnight.  Just because the sun has come out and the air has warmed up doesn't mean the transmission will heat up as quickly.

 

FYI, if the sensor is bad it will have no effect on trans temps (it won't cause it to overheat).  Your truck doesn't do anything other than flash a warning when it's near meltdown (262 degrees or something like that), it doesn't attempt to regulate the temperature.  The engine fans unfortunately are triggered only by coolant temp and A/C pressure in normal operation, so it's not like they'll fail to come on and keep the tranny cool if needed because they don't do that anyway.  I wish they did (it'd be really handy) but they don't.

[ChristopherDB]

In the morning when it was 80° outside, did it drop below 67° at night? Have you considered that there may be an issue with the temperature sensor that is causing and inaccurate, lower temperature reading?

[kennerz]

stock 6.2 here having the same problem. takes forever to hit 130. and when below it's just jumping around 15 to 20 deg hard to see 120 even. unless its hot on a long drive. my concern is different. I'm not sure if these trucks can get into a fuel consumption mode unless over 130 deg like a cts ( coolant temp switch) thats faulty and wont go into closed loop operation. when the trans is cold I get bad mileage. I have no trans mods. thinking it could be a faulty thermostat.

 

I left a black plastic duct off the grille when changing back to stock, so maybe too much airflow over the cooler. all new stuff is designed to run hot for emissions. just starting to look at it to try to figure it out and saw this topic.

[Bryn7471]

I have an appointment scheduled Tuesday after noon to see what’s going on.  Hopefully it’s just a bad sensor.  Just have to figure out the random vibration after that. 

[scott.moody.9401]

Mine does the same thing; rpms jump a few hundred (trans clutch locks and unlocks), a vibration accompanies the rpm jump, and the trans temp is either below ambient (impossible) or is erratic.

I have an appointment in 2 days

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