Diagram say it is a engine RPM sensor. It has three wires in the plug. Pin one is VRS +, Pin two is VRS -, Pin three is VRS G (ground). The wire numbers are, 1- 376A, 2- 375A, 3- 377C. There is no reference to the supply voltage. This may be a hall effect sensor and you should see a pulse on the signal out put when cranking. Most of the sensors are supplied 5 volts on these trucks. The cam sensor calls out the supply as 5 volts. Check the signal voltage when the engine is cranking.
ECU did not repair it, any other ideas? Besides what I previously posted, i noticed that I am getting 2.4v at the supply wire to the crank sensor, and 2.4v on the signal wire from the crank sensor. But the sensor does not show to be shorted.
It is the ECU. Not sure of the voltage on the GM engine.