Adding a resistive sensor

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Schuyler
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Adding a resistive sensor

Post by Schuyler »

So I am attempting to add a resistive coolant temp sensor from a saturn for my oil temp. I had found it online, on msextra I think, where people recommended using it. However, my understanding was I just put 1 lead to ground and 1 lead to an analog input (EGO2) on the ms3x card. Set to GM calibration. Did not work, and the values are crazy, and jumped a lot. Do I need to a 12V pullup with a 1k resistor to make this work? Or is there something else I am doing wrong?
elutionsdesign
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Re: Adding a resistive sensor

Post by elutionsdesign »

Ground is sensor ground, correct? Back to the MS unit?
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kjones6039
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Re: Adding a resistive sensor

Post by kjones6039 »

Schuyler wrote:just put 1 lead to ground and 1 lead to an analog input (EGO2) on the ms3x card.
I don't know anything about MS3, but I suspect that your ground should go to sensor return, as with all other MS sensor grounds!

I could be wrong, but I don't think so.

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Last edited by kjones6039 on Sun May 24, 2015 8:42 am, edited 1 time in total.
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grom_e30
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Re: Adding a resistive sensor

Post by grom_e30 »

did you fit a resistor to the ms3x card??
R65,R66,R67 are optional 'bias' resistors on the analogue inputs EXT_MAP, EGO2, SPARE_ADC respectively.
These would be typically used when connecting a resistive temperature sensor to one of the inputs. For
standard calibration, use a 2.49K resistor with a GM style coolant or air temperature sensor.
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billr
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Re: Adding a resistive sensor

Post by billr »

You are going to need a 2490 ohm pull-up to the 5V ref; you need to build an input circuit similar to that existing for the (standard GM) CLT and MAT sensors. Look at the V3.0 mainboard schematics.

Ah, I see I was too slow in typing! Besides, the rely above is more thorough.
Schuyler
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Re: Adding a resistive sensor

Post by Schuyler »

Thanks! I will add the resistor to the board. I did not use the sensor ground... Maybe I should consider moving the ground.
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