Innovate Motorsports LMA-3 - Manual (Page 10)

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connect the thermocouple probe to the LMA-3. You must use thermocouple wire to connect
the probe. If you do not, there will be an extra two-metal junction where the Copper wire meets
the Constantan wire of the probe. This extra junction will cause a large error in the temperature
readings.
Most Thermocouple probes are of the “grounded junction” type. This means that the “hot
junction” is also connected to the probe’s body. As this body is connected for example to the
exhaust manifold, the sensor wires are essentially grounded through that. The same is true if a
home-made thermocouple junction is used as described above by twisting the wires and if that
wire-twist is connected to some grounded engine part.
You can check if you have a grounded junction type by measuring between the probe body and
one of the Thermocouple wires. If you have continuity, you have a grounded junction.
The LMA-3 NEEDs a grounded junction.
If you don’t have a grounded junction, connect a wire between the TC- input of the LMA-3
and the ground terminal of the LMA-3.