Ok, 1990 bonneville LE 3.8L FWD 8th # on Vin is: C. I need to confirm if my friends car has a bad VSS before ordering. Her speedo & trip odom went out together, all @ once, Tach working fine. Havent been able to find an online manual for her car so as to be able to read specs and procedure to determine bad VSS, Someone already suggested, taking a resistance check! Great Idea except, what OHM,* should it be at to determine bad or good, I am aware that an open reads infinity, and a short reads damn near zero or 0, I read that the sensor sends out pulses in a square wave @ 4K for every mile, But isnt there a way to simply determine if theres any correct voltage or resistance value so as to be confident before ordering a $100 part? Just need an accurate answer or a link to a manual for testing reference. Any help would be appreciated ASAP. Thanks and great forum you have here!