# 2002 trailblazer service 4w light on **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** chevrolet, trailblazer\ **Created:** [March 8, 2010, 8:07pm UTC](https://community.cartalk.com/t/2002-trailblazer-service-4w-light-on/45767 "2010-03-08T20:07:25Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![35chevy](https://avatars.discourse-cdn.com/v4/letter/3/258eb7/32.png) [@35chevy](https://community.cartalk.com/u/35chevy)\ **Post date:** [March 8, 2010, 8:07pm UTC](https://community.cartalk.com/t/2002-trailblazer-service-4w-light-on/45767/1 "2010-03-08T20:07:25Z")
i tried to use my autoxray scanner and also my autotap software to find out what the problem is with the 4wservice light. neither will show any trouble codes. is this a return tochevy to find out what the problem is or are their sources to find the problem. thanks tom ---
**Author:** ![edb1961](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/edb1961/32/122_2.png) [@edb1961](https://community.cartalk.com/u/edb1961)\ **Post date:** [March 8, 2010, 8:31pm UTC](https://community.cartalk.com/t/2002-trailblazer-service-4w-light-on/45767/2 "2010-03-08T20:31:02Z")
Are you having any problems with 4wd drive engaging? I have a 2000 Blazer with Autotrac. The Service 4wd has lit up maybe 2 times in the 7 years I’ve owned it. Both times I disconnected the battery to reset the computer and the light never reappeared. I assumed if there was a real problem the light would reappear. Last year I had to replace the vacuum switch that controls the front axle engagement, but the Service 4wd light did not appear. ---
**Author:** ![35chevy](https://avatars.discourse-cdn.com/v4/letter/3/258eb7/32.png) [@35chevy](https://community.cartalk.com/u/35chevy)\ **Post date:** [March 8, 2010, 10:47pm UTC](https://community.cartalk.com/t/2002-trailblazer-service-4w-light-on/45767/3 "2010-03-08T22:47:53Z")
i can not select any thing on 4 wheel drive options. it is lock in 2wheel