Truck runs cold
#2
Here are a couple schematics looks like there is a violet/yellow wire running up to the ECT sensor.
1997 gauge cluster.pdf
engine-coolant-temperature-ect-sensor-connector-pinout-data 1997 Dodge.pdf
engine-coolant-temperature-ect-sensor-test-specifications 1997 Dodge.pdf
You might also use a IR temp probe to see what temp the engine water neck outlet is really reading.
1997 gauge cluster.pdf
engine-coolant-temperature-ect-sensor-connector-pinout-data 1997 Dodge.pdf
engine-coolant-temperature-ect-sensor-test-specifications 1997 Dodge.pdf
You might also use a IR temp probe to see what temp the engine water neck outlet is really reading.