Trans Temp sensor with FAST

[Mike E]

I'm thinking about adding a trans temp sensor and logging it with the FAST box/ FAST dash. Can I use a GM 2 wire coolant temp sensor? If not what do most people run?

 

[J-B Racing]

Mike. That would work. I think the pn is TX3 on Blue Streak.

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[J-B Racing]

Or tx1 I have to check..

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[karolko]

oooooooooo nice idea. I have a manual trans temp gauge, but this sounds like fun.

So here is what I am thinking, when you are in XFI program you can go to Sensor calibration and look at the CTS calibration file. the line is almost linear, but from that you can calculate the gain and offset, unless SOMEONE (Hint hint) happens to have these numbers available. It would make for a great starting point at the very least.

the problem however is that FAST is only designed to accept 0-5 V inputs, and the stock CTS sensors are 12volt. I guess we need to look for 0-5v cts sensors? Do any other vehicles use 0-5v CTS sensors. ( please please no one say the F- word)

Adrian

 

[turbobitt]

I just use the 8 Chanel EGT module and use one of the two spares for trans temp.
AG


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[Mike E]

oooooooooo nice idea. I have a manual trans temp gauge, but this sounds like fun.

So here is what I am thinking, when you are in XFI program you can go to Sensor calibration and look at the CTS calibration file. the line is almost linear, but from that you can calculate the gain and offset, unless SOMEONE (Hint hint) happens to have these numbers available. It would make for a great starting point at the very least.

the problem however is that FAST is only designed to accept 0-5 V inputs, and the stock CTS sensors are 12volt. I guess we need to look for 0-5v cts sensors? Do any other vehicles use 0-5v CTS sensors. ( please please no one say the F- word)

Adrian

The CTS is really just a thermistor (resistor that changes resistance with temp). In theory you can put 5V to it and at 0 resistance you get 5V back to the ECU. As long as it's linear and has enough range it should work. But I would like to hear from someone that's using it.

 

[karolko]

the thing that confuses me is that the stock sensors are only two wires, a ground and a second wire( I assume it is the voltage wire) what I cannot understand is how it works, the ground is a common ground on the xfi, and the other wire is a voltage wire,

the xfi map for cts does however go from 0-5volts, so maybe it is a 5volt sensor?

I too would also like someone to confirm if they have used a stock sensor so something like this.

Another application I have heard of people doing is testing the pre and post intercooler air temps, ( which are basically the same type of sensor.

Allan, I don't have a EGT probe setup, but that is a great and simple idea as well. That way you don't have to use up 1 of the 8 analog channels.

Adrian

 

[Mike E]

Ok, so 5V on one side and the other side to the ECU is the wrong way to do it.

If I understand right you put 5V to one side of the sensor with a pull up resistor inline. The other pin goes to ground. You hook your analog input on the 5V side after the pull up resistor. You may need another resistor on the analog input. I'm going to let the guy I bought my FAST from hook that up when when he gets a chance.

 

[karolko]

Mike look at the FAST Schematics for the I and CTS. this is where all my confusion is coming from.

I'm probably being a retard here. More than likely.

Adrian

 

[Mike E]

I did. There are two connections to the ECU (CTS signal input and signal return). There is probably some more internal circuitry (resitors) in the ecu that we don't see.

The only reference I have found to using a GM CTS as a temp sensor is with the megasquirt stuff. Scroll down about halfway and look at the schematic above the drawing of a coolant temp sensor. http://www.megamanual.com/v22manual/mwire.htm