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Sharing Speedhut Sending Unit With ECU


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I have a G4X Monsoon and a Speedhut temp gauge. The gauge comes with a sending unit and uses a 5v reference voltage that it generates. I'm hoping to share the sending unit with the ECU and I got a voltage to temp table form Speedhut and added the table to the AN2 pin on the ECU. I realize I can't use one of the dedicated TEMP inputs because I'd end up with two pullup resistors so I'm using an AN Volt pin instead.

My questions are:

1. Should I use the 5v power from the Speedhut gauge or the 5v from the ECU?

2. When I make a sweep temperature gauge for the tuning window it only shows from 0.0-200. Shouldn't it read the 140-300 range dictated by the table?

3. Would is be smarter to use an output to send table based voltages to the gauge from the ecu instead? if so how would I do that?

I'm doing this all on the bench still but was hoping to get a config that's close before this goes in the car.  Thanks.

Screenshot 2024-01-16 at 11.32.50 AM.png

Screenshot 2024-01-16 at 11.39.44 AM.png

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  1. Not sure what you mean here, there shouldnt be 5V connected anywhere.
  2. Your gauge is displaying the voltage on AN Volt 2 pin.  You should have the ECT runtime displayed on the gauge.  The gauge range, warning levels, divisions, decimal places, etc can all be changed in the gauge properties.  If it is set to "Use parameter display min/max" it will use the global parameter settings.  
  3. No, provided the gauge uses a 5V pull-up and not 12V then it will be best to share the sensor as you propose.
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Hi.  Thanks for the prompt and helpful reply.


The sending unit is a 2 wire so I thought I was supposed to run 5v to one wire and then connect the other to the "AN Volt 2" pin on my ECU so it can read the voltage after the sender.  Is that incorrect?

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One pin is ground and the other is signal.  The signal wire will have a pull-up connected to it in the gauge.  

So the ecu AN Volt needs to be connected to the same signal wire as the gauge (the one that is not at ground).  

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