2 replies to this topic

[tynor]

As a diversion from the last couple weeks protest marathon, I'd like to ask a question about setting up my new traqmate data system (I'm ditching my old AIM Solo - soon to be for sale if anyone is interested --  for the traqmate since that's the dominant system in use here in the southeast and I'm in need of comparing my pathetic laptimes to those mo' betta than I...)

 

Has anyone successfully tapped into the stock water temp sensor.  I've directly tapped the wire feeding the stock dash gauge (pin 2A on the back of the 1999 dash).  I've tried setting up the voltage mapping, but it does not appear to be consistent and reproducible - each time I test, I get a different set of voltage vs. temperature mappings. (I'm comparing both my mechanical autometer gauge and OBD2 data to the voltage reported by the traqmate dash display).  

 

Maybe reference voltage is varying with battery charge?  Maybe I need some sort of pull down resistor, but I have no idea how to decide if I do or what size to use.  

 

I am a software guy - I'm not afraid to touch hardware, but I do best when I have step by step instructions.       Any advice?

 

Thanks,

Steve

[KentCarter]

Yes... a pull down resistor would do the trick. I'd try a 470ohm 1/2W resister between the 12V output on the Tmate and the sensor and tie the analog input in between the resistor and the sensor. 

[tynor]

Yes... a pull down resistor would do the trick. I'd try a 470ohm 1/2W resister between the 12V output on the Tmate and the sensor and tie the analog input in between the resistor and the sensor. 

 

I'll try that.  How did you arrive at the 470 ohm and 1/4 watt values?   The Traqdata docs show a variety of values for various sensors, but its not clear to me how one would know what resistance or wattage is needed for any given sensor... (e.g. the AEM temp sensor example uses a 2.2k ohm 1/2 watt resistor).