1996 4L80E P0713 Transmission fluid temp sensor problems

[Jbarry14]

I have a 1996 Chevy K3500 with the 5.7L and 4L80E

I have a P0713 Code. Last weekend I dropped the pan and installed a new internal wiring harness and TFT sensor. I put it all back together and that did not solve my problem. The transmission does not shift at the correct times, but when I clear the code, it shifts correctly. I checked the external wiring and the Wiring at the ECM. I do have a tuned ECM from blackbear. I am not sure what else could be causing this problem. Does anyone have any suggestions on what I could try or where else I could look?

 

[NickTransmissions]

I have a 1996 Chevy K3500 with the 5.7L and 4L80E

I have a P0713 Code. Last weekend I dropped the pan and installed a new internal wiring harness and TFT sensor. I put it all back together and that did not solve my problem. The transmission does not shift at the correct times, but when I clear the code, it shifts correctly. I checked the external wiring and the Wiring at the ECM. I do have a tuned ECM from blackbear. I am not sure what else could be causing this problem. Does anyone have any suggestions on what I could try or where else I could look?

When did this start happening? After the BB tune or was the tune already installed and then this happened more or less out of the blue?
What did the fluid look like and bottom of the pan when you pulled it? Trans temperature when the code is setting?

 

[Jbarry14]

When did this start happening? After the BB tune or was the tune already installed and then this happened more or less out of the blue?
What did the fluid look like and bottom of the pan when you pulled it? Trans temperature when the code is setting?

This has been going on for a while. But my engine was starting to go, so I replaced the engine and now trying to fix this problem. When I replaced the engine, I had the blackbear tune done. The fluid in the bottom of the pan was a little brown. I am not sure of the trans temp. I don't believe I currently have a way to read it. I would have to install an aftermarket gauge.

 

[NickTransmissions]

This has been going on for a while. But my engine was starting to go, so I replaced the engine and now trying to fix this problem. When I replaced the engine, I had the blackbear tune done. The fluid in the bottom of the pan was a little brown. I am not sure of the trans temp. I don't believe I currently have a way to read it. I would have to install an aftermarket gauge.

That code will set if the trans temp is too hot as well as if the temp sensor on the harness is malfunctioning...It may be beneficial to install a temp and line pressure gauge - you can tap into the line pressure test port location on the driver side behind the bell housing and then run your lines to a gauge pod in the vehicle...This assumes you drive it a lot and want to keep an eye on that stuff.

What harness did you buy and install? I use either OEM for the newer stuff or Rostra harnesses for anything older...

 

[someotherguy]

you can tap into the line pressure test port location on the driver side behind the bell housing and then run your lines to a gauge pod in the vehicle...This assumes you drive it a lot and want to keep an eye on that stuff.

I was going to suggest it but figured since you were responding that you would offer your recommendation on how/where. I've put the temp sensor in that same spot on a couple different trucks (most importantly on a '96 C3500 tow truck) and caught some flak from people that said it wasn't an accurate place to read the temp. My amateur-level tests using an IR temp gun scanning all around the pan, case, torque converter, etc. showed same temps (or a neglible 1-2 degree difference) from what the gauge was reading, so I was fine with it.

Richard

 

[NickTransmissions]

I was going to suggest it but figured since you were responding that you would offer your recommendation on how/where. I've put the temp sensor in that same spot on a couple different trucks (most importantly on a '96 C3500 tow truck) and caught some flak from people that said it wasn't an accurate place to read the temp. My amateur-level tests using an IR temp gun scanning all around the pan, case, torque converter, etc. showed same temps (or a neglible 1-2 degree difference) from what the gauge was reading, so I was fine with it.

Richard

Yea it isnt the most "accurate" - for that id do a B&M aluminum deep pan with the temp gauge port already tapped on the side. Better cooling, more capacity and the temp gauge. Id still run a separate mechanical pressure gauge out of the port behind the bell.

Here's a B&M pan on my TH475...

You must be registered for see images attach

 

[Schurkey]

'96? Has the computer had the wire-harness update performed per the GM service bulletin?

Seems to me that there's 3 or 4 wires involved, and it has to do with trans durability more than trans temp...but it'd be worth checking.

A search of this site would provide a copy of the bulletin--or perhaps someone remembers the details

 

[Jbarry14]

That code will set if the trans temp is too hot as well as if the temp sensor on the harness is malfunctioning...It may be beneficial to install a temp and line pressure gauge - you can tap into the line pressure test port location on the driver side behind the bell housing and then run your lines to a gauge pod in the vehicle...This assumes you drive it a lot and want to keep an eye on that stuff.

What harness did you buy and install? I use either OEM for the newer stuff or Rostra harnesses for anything older...

I will look into getting a gauge. I did want to install a trans temp gauge.

I did isntall a Rostra harness that has a fluid temp sensor on the harness

'96? Has the computer had the wire-harness update performed per the GM service bulletin?

Seems to me that there's 3 or 4 wires involved, and it has to do with trans durability more than trans temp...but it'd be worth checking.

A search of this site would provide a copy of the bulletin--or perhaps someone remembers the details

I will have to look into to this update. As far as I know this has not been performed. Thanks for the info on that.

Yea it isnt the most "accurate" - for that id do a B&M aluminum deep pan with the temp gauge port already tapped on the side. Better cooling, more capacity and the temp gauge. Id still run a separate mechanical pressure gauge out of the port behind the bell.

Here's a B&M pan on my TH475...

You must be registered for see images attach

I do eventually want to put a deep pan on it like this. This is what I wanted to do originally when I dropped the pan to replace the harness, but I want to make sure I can solve this problem and get the trans shifting right before I spend the money on a deep pan.

 

[Supercharged111]

Buy a bigger pan? Meh. It'll only prolong the act of heating up the fluid. I zapped a bung into the stock pan for my dually.

You must be registered for see images attach

1500 is due for a purge, so it'll get one too. The fluid changes temp MUCH faster than the test port indicates.

 

[NickTransmissions]

I will look into getting a gauge. I did want to install a trans temp gauge.

I did install a Rostra harness that has a fluid temp sensor on the harness

I will have to look into to this update. As far as I know this has not been performed. Thanks for the info on that.

I do eventually want to put a deep pan on it like this. This is what I wanted to do originally when I dropped the pan to replace the harness, but I want to make sure I can solve this problem and get the trans shifting right before I spend the money on a deep pan.

There's some that like the deep pans and think they're worth it and others that don't - ultimately it's your call but I like them (the aluminum ones) because they add fluid capacity, dissipate / exchange heat faster than sheet metal pans, have drain plugs (though you can weld one in to a stock pan) and look nice...I always recommend them for anything heavy duty and/or high performance if ground clearance allows for it...

That Rostra harness should work for any years within the specified range (ditto for the temp sensor) so def check into @Schurkey 's rec for the PCM update as that could be the source of the problem...

Buy a bigger pan? Meh. It'll only prolong the act of heating up the fluid. I zapped a bung into the stock pan for my dually.

Yea, do whatever you think works for you but if heat isn't managed properly it doesn't matter what pan you have installed...All other things equal (i.e. proper heat management) a deeper aluminum pan w/extra capacity helps the transmission more than it hurts....Depending on application, it may be strongly recommended or just optional so but for some, including you, perhaps the cost/benefit isn't there.