89 Subaru justy vehicle speed sensor testing


#1

My Chilton manual says “1. switch the ignition on and check the voltage on VSS terminal 29 of the ECU. 2. The voltage should vary above and below 2 volts with the vehicle moving slowly.”
I think I’ve found the correct wire, but I’m not sure about the testing procedure. Would I unplug the wire harness and test the wire? If so, would I push the car to check the voltage, as it will not start with the harness unplugged?
Thanks for any advice.


#2

It’s called back-probing.

It’s done without disconnecting the connector.

Tester


#3

Leave the plug connected and back probe the connector to make the connection. If you don’t have some needle point probes you can use a pin and stick it into the back side of the plug where the wire comes out. Then use a jumper wire to connect the meter probe to it or tape the pin to the probe tip.