2009 Duramax Transmission Temp Climbs very fast when stopping aggressively

[idagon]

Hi All, my 09 Duramax has normal trans temps when driving, pulling, even going over a rough bumpy road. But when I do a fairly aggressive stop the temp climbs very rapidly. After coming to a stop it will sometimes continue to climb until temp reads ----.

Changed harness in pan, changed pressure switch/temp module in pan.
Fluid is full.

sometimes will set a P0712 code.

Any ideas?

 

[Mike L.]

Possibly a bad gauge.

 

[idagon]

the edge insight always has the correct temp but the digital display in the speedo is the one that moves. if I do it 2 to 3 times in a row i get a code

 

[idagon]

the gauge should not set the code should it Mike?

 

[Awenta]

Does the temp on the insight go up too or stay normal?

Sent from my SM-N910V using Tapatalk

 

[idagon]

the insight gauge stays normal

 

[duratothemax]

I would see if you can put a manual gauge on there to confirm.

The display on the Edge insight is supposed to exactly match the gauge on the dash because they are both reading off of the databus.

Are you absolutely sure you're reading the correct transmission temp PID on the Edge?

I think you have an intermittent wiring problem.

 

[idagon]

Yes I am sure the insight is reading the trans temp. Both the insight and the dash digital display show the exact same temp readings until the dash goes haywire.

I agree with the wiring problem, so I replaced the harness inside the tranny. Ive done a wiggle test with the wiring under the truck.

I have also seen the problem occur when turning to the left a little fast on a curvy road.

I cant understand either why one gauge goes off when they both read off the same bus.(unless the insight displays the last known good reading when the circuit goes open but the insight does not go up at all when the problem occurs.

 

[Awenta]

If a regular gauge confirms the temps are in check then I'd be looking at the gauges

Sent from my SM-N910V using Tapatalk

 

[idagon]

Ok maybe it is the gauge, can someone verify that a bad factory digital readout in the instrument cluster can throw a P0712 sensor low code?

I do not believe so.

this is not a gauge like the older needle gauge used before 2007.

 

[duratothemax]

Ok maybe it is the gauge, can someone verify that a bad factory digital readout in the instrument cluster can throw a P0712 sensor low code?

I do not believe so.

this is not a gauge like the older needle gauge used before 2007.

You're correct. This is not a cluster problem. I think everyone is forgetting that 2007.5+ trucks have the digital trans temp gauge in the driver info center.

its a digital display that shows whatever info it is told to show...come on think about it. The TCM gets the reading right from the sensor...the TCM broadcasts that sensor reading over the databus. The cluster picks up the temp reading over the databus and displays it on the DIC.

Does everyone think the cluster is somehow just magically "not reading the data correctly"?????? No. This stuff doesnt work that way.

Its a wiring problem somewhere between the trans and the TCM, I guarantee it. The original poster said it goes crazy when he goes around a corner or brakes aggressively......isnt that a red flag that its a wiring harness problem?

And as far as the edge showing the same temp and not following the DIC...it probably just defaults to the original value if it sees a fault with the circuit...

Ben

 

[idagon]

UPDATE:

After doing a harness wiggle test and finding nothing. I took it on a long trip and noticed that the insight does in fact move to very high readings as well as the digital gauge BUT...

After the trucks stock temp digital gauge goes to ---- and stops showing a reading, the insight shows the correct temp at all times even after 2 hours of driving.