Erratic Trans Temperature

[JLee]

My Edge CTS has started showing some strange transmission temperature readings. I'm almost always towing something and in stop & go traffic the temp will climb and set off the alarm on the CTS (>220º). The unusual part is it jumps up and down 10-20º. I have a HD TC so I kind of expect to see a little more heat in stop and go and once I get back into lockup the temps fall back into the 180's. I think I read somewhere that there is a warm up mode where a valve restricts cooling and maybe this is malfunctioning? Anybody had any experience with this?

 

[BGlidewell]

there is a check valve in the output line. Its a real moneymaker for transmission shops when it sticks closed. Especially for those who dont have a transmission temperature gauge... I've been meaning to take mine out, but I'm going to have a hose made to replace it.

 

[cerberusiam]

Set the alarm to 240, thats a more realistic number. The 220 in stop and go driving is normal, its the way its designed to run.

The temp jumping around sounds typical for the electronic monitors, possibly a bad transducer in there.

The check valve will never cause those types of bounces in the temp, just consistently higher than normal readings in it is too restrictive.

 

[BGlidewell]

The temp jumping around sounds typical for the electronic monitors, possibly a bad transducer in there.

The check valve will never cause those types of bounces in the temp, just consistently higher than normal readings in it is too restrictive.

Mine jumps from 100-200 and I have the sender in the cooler line. IIRC number 1 in the above schematic.

 

[TCDiesel]

The thermostat in the Auxiliary cooler maybe acting Up,If Cerb doesn't have the link to the comp D removal ,I will look for it,But I think Cerb has it saved.

 

[rscurtis]

Mine jumps from 100-200 and I have the sender in the cooler line. IIRC number 1 in the above schematic.

That's normal, as that fluid was just heated by the torque converter. If you want to know the real temperature, measure the temperature in the pan. Watching the line temp. just gives you something to worry about.

 

[cerberusiam]

That's normal, as that fluid was just heated by the torque converter.

Uh uh, think about it a minute. Imagine the load and power need to flash heat the fluid from 100 to 200 and it doesn't work. The best you can do on a good gauge is a fairly fast rise in temp, and that is foot on the floor with huge load or steep grade.



What I think the is describing is a jump in the needle to from 100-200. Same as the OP is describing a bounce on the electronic monitor. It is either a guage or sender problem when the needle, or numbers, flash over a wide range.

 

[BGlidewell]

Maybe I should have used the word sweep, not jump? What should the resistance be across the sender?

 

[cerberusiam]

What should the resistance be across the sender?

That will vary with the temp, it show the the gauge reads the sender.

Just how fast does it go from 100 tot 200 and in what conditions?

 

[BGlidewell]

That will vary with the temp, it show the the gauge reads the sender.

Just how fast does it go from 100 tot 200 and in what conditions?

I notice it when I'm 1-2-3 3-2 2-3 after the engine has been at operating temp for a while. Normally the trans cooler line gauge registers just above 100. I have a double deep pan. The sweep goes down after 4th and is like a slow fall over a mile or so. I don't think I've ever noticed it on the way up. I just see it higher than it normally is and focus on it.

 

[cerberusiam]

I notice it when I'm 1-2-3 3-2 2-3 after the engine has been at operating temp for a while. Normally the trans cooler line gauge registers just above 100. I have a double deep pan. The sweep goes down after 4th and is like a slow fall over a mile or so. I don't think I've ever noticed it on the way up. I just see it higher than it normally is and focus on it.

Did you remove or disable the thermostat in the front cooler? Normally, the trans temp should never read under 140 as that is the set point it shuts off thru the cooler. A rise in temp with a lot of shifting and lack of lockup is normal, and, in stop and go driving empty it will hit 220 easily. 200 is just normal driving.

 

[BGlidewell]

Did you remove or disable the thermostat in the front cooler? Normally, the trans temp should never read under 140 as that is the set point it shuts off thru the cooler. A rise in temp with a lot of shifting and lack of lockup is normal, and, in stop and go driving empty it will hit 220 easily. 200 is just normal driving.

no, nothing removed... sender is suspect I guess. Maybe I should test it with a pot of water and a thermometer.