jthom5147 Posted July 15, 2011 Share Posted July 15, 2011 Hey everyone, I'm working on my wiring diagram and making sure i know where to pull wires from / to. I will be using a relay board with MS2 v3.57. Just for reference, IAT signal wires pair with positions 16 and 17 on the j20 terminal. CLT pairs with 18 and 19. 17 and 19 are the sensor return ground points. My question is: do the stock turbo head temp sensor(which i would like to use as my coolant temp sensor) and/or GM open element IAT sensor have a polarity to the way the wires need to be hooked up. Here is a link to the IAT i am using: IAT Sensor - DIYAutotune I.e. does it matter which wire on the IAT goes to terminal 16 and which to 17? and which from the datsun head temp sensor goes to 18 and which to 19? or do they work the same way either direction of connection? Thank you all for reading and perhaps helping! Quote Link to comment Share on other sites More sharing options...
jthom5147 Posted July 16, 2011 Author Share Posted July 16, 2011 (edited) I guess I'm either overthinking or underthinking this. Since the sensor is in essence nothing more than a resistor that has variable ohm values depending on the temperature of the resistor itself. The MS will be reading the amperage for a given voltage across said resistor and then working it backwards with ohm's law to find the corresponding resistance value. MS will then find the corresponding temperature from the interpolated ohm to temp calibration graph with the derived resistance. But, long story short, since the sensor is a resistor.... the resistance value should not deviate with direction of current flow but rather only with temperature change. Edited July 16, 2011 by jthom5147 Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 16, 2011 Share Posted July 16, 2011 With the Nissan and the GM ones that I am familiar with, there is no polarity needed. Quote Link to comment Share on other sites More sharing options...
jthom5147 Posted July 18, 2011 Author Share Posted July 18, 2011 With the Nissan and the GM ones that I am familiar with, there is no polarity needed. Thank you! Quote Link to comment Share on other sites More sharing options...
jacob80 Posted July 29, 2011 Share Posted July 29, 2011 For the GM sensors, they are usually yellow and black wires coming off the pig tail. In general, black is used for ground, so thats what I go with. Quote Link to comment Share on other sites More sharing options...
FricFrac Posted August 18, 2011 Share Posted August 18, 2011 I guess I'm either overthinking or underthinking this. Since the sensor is in essence nothing more than a resistor that has variable ohm values depending on the temperature of the resistor itself. The MS will be reading the amperage for a given voltage across said resistor and then working it backwards with ohm's law to find the corresponding resistance value. MS will then find the corresponding temperature from the interpolated ohm to temp calibration graph with the derived resistance. But, long story short, since the sensor is a resistor.... the resistance value should not deviate with direction of current flow but rather only with temperature change. Almost... MS will read the voltage dropped across the resistor - it doesn't care what the current is. The sensor is probably half of a voltage divider and the other half will be on the MS PCB. The MS PCB will use an ADC to read the voltage. You calibrate your thermal sensor reading in your MS tuning software. EF & EC - 88 in the '83 280ZX FSM (www.xenons130.com) gives you a graph of the thermal sensor values based on temperature. Since it's a variable resistor it doesn't really care which way the wires are hooked up.... Quote Link to comment Share on other sites More sharing options...
Challenger Posted November 11, 2011 Share Posted November 11, 2011 What do you mean by EF & EC - 88? I cant find it in the FSM for the 1983 280zx. Quote Link to comment Share on other sites More sharing options...
DCZ Posted November 15, 2011 Share Posted November 15, 2011 On this same topic, when you calibrate the temp sensor, you need pairs of temperature/resistance values and an "offset". What does that offset refer to? The y-offset in the FSM graph? What are the units to the offset? Quote Link to comment Share on other sites More sharing options...
BLOZ UP Posted November 16, 2011 Share Posted November 16, 2011 You talking about the bias resistor? It's installed on the MS board. Systems built for GM sensors have a 2490 Ohm bias resistor installed. Usually. http://www.bgsoflex.com/v22/assem.html - Step 53 explains it. Quote Link to comment Share on other sites More sharing options...
macambra Posted November 16, 2011 Share Posted November 16, 2011 What do you mean by EF & EC - 88? I cant find it in the FSM for the 1983 280zx. I had some free time...Notice the bottom left corner. Quote Link to comment Share on other sites More sharing options...
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