according to the manual on the new 06 i just got, these trucks are eqquipped with an indicator light to alert you if tranny temps get too high. What is the need for a tran temp gauge ?

 

to know before it's too late! and so you can watch how hot it gets and stop or change gears or pull over before it's to hot.

I bet the light comes on after the fluid is so hot that it has already broke down the ATF.

I will look and see what temp the light goes on at......

 

Somewhere I read light comes on about 280-290 degrees, as you said, awfully hot at that point. Temp gague would allow you to see that coming and try to cool it down long before that temp.

 

here it is.................




A transmission over-temperature indicator is standard equipment on all instrument clusters. However, on vehicles not equipped with an optional automatic transmission, this indicator is electronically disabled. This indicator is located on the left side of the instrument cluster, to the left of the fuel gauge.

The transmission over-temperature indicator consists of a stencil-like cutout of the text "TRANS TEMP" in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents the indicator from being clearly visible when it is not illuminated. A red Light Emitting Diode (LED) behind the cutout in the opaque layer of the overlay causes the "TRANS TEMP" text to appear in red through the translucent outer layer of the overlay when the indicator is illuminated from behind by the LED, which is soldered onto the instrument cluster electronic circuit board. The transmission over-temperature indicator is serviced as a unit with the instrument cluster.

The transmission over-temperature indicator gives an indication to the vehicle operator when the transmission fluid temperature is excessive, which may lead to accelerated transmission component wear or failure. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Programmable Communications Interface (PCI) data bus.

The transmission over-temperature indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED will always be off when the ignition switch is in any position except On or Start. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn on the transmission over-temperature indicator for the following reasons:


Bulb Test - Each time the ignition switch is turned to the On position the transmission over-temperature indicator is illuminated for about two seconds as a bulb test.
Trans Over-Temp Lamp-On Message - Each time the cluster receives a trans over-temp lamp-on message from the PCM indicating that the transmission fluid temperature is 135°C (275°F) or higher, the indicator will be illuminated and a single chime tone is sounded. The indicator remains illuminated until the cluster receives a trans over-temp lamp-off message from the PCM, or until the ignition switch is turned to the Off position, whichever occurs first. The chime tone feature will only repeat during the same ignition cycle if the transmission over-temperature indicator is cycled off and then on again by the appropriate trans over-temp messages from the PCM.
Actuator Test - Each time the cluster is put through the actuator test, the transmission over-temperature indicator will be turned on, then off again during the bulb check portion of the test to confirm the functionality of the LED and the cluster control circuitry.
The PCM continually monitors the transmission temperature sensor to determine the transmission operating condition. The PCM then sends the proper trans over-temp lamp-on or lamp-off messages to the instrument cluster. If the instrument cluster turns on the transmission over-temperature indicator due to a high transmission oil temperature condition, it may indicate that the transmission and/or the transmission cooling system are being overloaded or that they require service. For further diagnosis of the transmission over-temperature indicator or the instrument cluster circuitry that controls the LED.

For proper diagnosis of the transmission temperature sensor, the PCM, the PCI data bus, or the electronic message inputs to the instrument cluster that control the transmission over-temperature indicator, a diagnostic scan tool is required.




So at 275 degrees the light comes on. ATF and oil break down at 300 degrees, not much room for a mistake.
I would buy a gauge.

 

Thank you for the reseach. I tow heavy so guess i will get one oalong with an egt gauge. Will proably get a dual mount that goes over the steering wheel colum

 

I considered analog guages in my new truck. I even removed my pyro and a-pillar mount from the 03 to install in the new one. I too wanted to monitor the trans temp as I tow close to the limit on combined weight. I just installed an Outlook monitor from bully dog as I did not want to start hanging multiple guages everywhere on this truck. Some folks really like the look of multiple guage setups but the Outlook, Commander or Attitude monitors are options as well. There is quite a list of things you can monitor with these too although I will never use some of them.

 

Does anyone know where the sensor is located for the "transmission over-temperature indicator"? In other words the "idiot light" is telling us that the temp is over 275 degrees, WHERE????????????????????

 

I will have a look today and get back to you.

 

It's inside the transmission, it's part of the governor pressure sensor.

the GPS and tans temp sensor are the same part.

you have to take the trans pan off to get to it.

here is some more info about the trans temp sensor......


Transmission fluid temperature readings are supplied to the transmission control module by the thermistor. The temperature readings are used to control engagement of the fourth gear overdrive clutch, the converter clutch, and governor pressure. Normal resistance value for the thermistor at room temperature is approximately 2000 ohms.

The thermistor is part of the governor pressure sensor assembly (2) and is immersed in transmission fluid at all times.

OPERATION
The PCM prevents engagement of the converter clutch and overdrive clutch, when fluid temperature is below approximately 10°C (50°F) .

If fluid temperature exceeds 126°C (260°F) , the PCM causes a 4-3 downshift and engage the converter clutch. Engagement is according to the third gear converter clutch engagement schedule.

The Tow/Haul lamp in the instrument panel illuminates when the shift back to third occurs. The transmission will not allow fourth gear operation until fluid temperature decreases to approximately 110°C (230°F) .