2002 jeep liberty speed sensor Two yellow wires one with a blue stripe which wire is plus and - on the sensor?

There isn't a simple plus and minus on a Jeep Liberty speed sensor's wires. It's not a voltage source; it's a sensor that produces a signal. The two wires (yellow and yellow/blue) carry that signal. One is the signal wire and the other is a ground (return) wire. You cannot determine polarity by color alone.

To identify which wire is which, you need a wiring diagram specific to your 2002 Jeep Liberty's year and engine. The diagram will show the sensor's wire connection to the PCM (Powertrain Control Module).

Without the wiring diagram, any attempt to determine polarity by testing could damage your PCM or the sensor. Do not attempt to test the wires without the proper diagram and understanding of automotive electronics.

Instead of trying to guess, consult a repair manual for your specific Jeep Liberty model. The manual will have the wiring diagram and explain the proper testing procedures. You can often find these online or at auto parts stores.