Hi everybody I have a 99chevy express 1500 and I noticed my speed gauge wasnt moving properly and my anit-lock brake light came on.. So I researched and figuered the VSS may be bad. I replaced it and drove a few hours. That seemed to do the job, but today I drive it and its back doing tje same thing... Anybody can tell me steps to check before I may have to buy a ECM OR PCM. Or what it may be? Thanx as I'm trying to do it myself.

 

What does it do? Does it stick - then jump up to speed... or down to speed? Does it move constantly above/below speed? Random who-knows-where-it's-going stuff?

Mine has a sticky gauge 'motor' (on instrument cluster circuit board - powers the speedo needle) that sometimes sticks & then jumps up (or down) to correct speed. Those are available on eBay if that's the issue. (Requires de-soldering old gauge motors & soldering in new ones.)

RE light: Are your front brake sensors ok?

Do you have a code reader to see what's up with that brake light? I have this one ( http://amzn.to/1WAzWKy from Amazon) that right now is selling for $8.00! I use it with my android smartphone and a free app (Torque Free). I have and use this exact unit & was using it today after doing a tune up. It does darn near anything the fancy $100 units does and it will even look up the fault codes on the internet through the Torque Free app. http://amzn.to/1WAzWKy