I got a 2000 Lightning a year and a half ago and have been reading a lot of the post archives on this site for a while. a few weeks ago I installed a tripple gauge pod with the lunar series gauges, and they are great. I have a question, though, on the transmission temperature... from reading the posts, I am under the impression that normal operating temp is about 180 ... and that cooler is better. the part that worries me is that my trans temp gauge shows that the trans temp eventually gets up to, and stays at, 250 (!!!) during an hour of normal driving (mixed highway and back road)
I am thinking that this is really bad and not normal, even for stock. I mounted the temp sender in the suggested spot (the access hole on the driver's side)
Also, the stck engine temp gauge shows that the engine is at the normal operating temp... Other than the high trans temp reading, the truck drives perfectly. In addition, I just had the trans fluid changed a month ago.

Does anybody have an idea of why it would make so much heat under normal driving (no burnouts or anything)? or is this really normal for a stock truck ?

thanks for the help

 

Ground the guage.

The guage instructions claim that the sensor in the tranny will self ground but it will not. You need to ground your guage (on the back) to somewhere in your truck and you will get a good reading. Mine did this at first and when I grounded it the problem was fixed

Ed

 

What is the normal driving temp under normal conditions and under severe conditions?
TB

 

I've got no idea what normal is, but I get around 150 driving on the highway. It'll get up to 200 if it is the middle of the summer and I'm driving agressively in stop and go traffic for a long time...

Coldie

 

http://www.txchange.com/heatchrt.jpg

 

Ed,

thanks for the idea about grounding the gauge... it is a good one. I put a wire from the base of the temp sender to the bolt that atttaches the oil filter bracket to the engine. the resistance between ground and the temp sender base went from 3.3 ohms to .4 ohms. I took the truck for a test drive and the temp still got to 210 in 15min of moderate driving... still too high, I think. perhaps the sender is still not grounded properly. Where did you run your ground wire to ??



tb,

the temp doesnt seem to change much no matter how hard I drive. the temp just slowly climbs into the 200s.


kj

 

There is a way to test the gauge and the sensor..

Wish I could remember for sure..
anyone recall?

 

to test:

Put the sender in water? at a particular temperature?

Coldie

 

No.....mine would peg out when the key was turned on...you unhook the ground..or the sensor wire and the gauge should fall to zero....and vice versa..I believe...

 

No man, don't ground the sensor. Ground the guage itself. Your temp guage has a ground connection on the rear. Make sure it is grounded. the sender will ground itself, but you need to physically ground the guage like you would any other guage or an amplifier so forth....

The instructions say you don't, so I don't know if you did or not, but that made the difference in mine

 

No man, don't ground the sensor. Ground the guage itself. Your temp guage has a ground connection on the rear. Make sure it is grounded. the sender will ground itself, but you need to physically ground the guage like you would any other guage or an amplifier so forth....

The instructions say you don't, so I don't know if you did or not, but that made the difference in mine

 

Normal temp in the winter is 110-150 highway/some stop and go. Summer 170 anything over 190 will start damaging the trans. Its a good idea to run a larger pan, preferably the FMS one that has cooling fins and holds an extra 4 qrts of fluid to help keep temps down. KJJ you said you just had the fluid flushed, check to make sure theres enought fluid in there, maybe they didnt top it off all the way. Engine running and at opp. temp when checking. Hope this helps

 

If you used teflon tape on the sensor you should pull it and remove the teflon..

 

just thought I would wrap up this thread with the fix... grounding the post on the back of the trans temp gauge seems to have solved the problem, as Ed suggested. the gauge now reads about 125 on the highway.

thanks for the good ideas guys

kj