Why wont my 2002 trailblazer not shift into first or overdrive

SOURCE: The reverse lights wont work,

If bulbs and fuses are good, the remaining thing is the gear selector switch on the transmission.

SOURCE: i have a 2002 trailblazer

Hello irvigiv. Begin by checking your transmission fluid level. If the level is low, it will not shift properly causing the problem you are experiencing. Once you have the correct level [and always err on the side of slightly over filled vs slightly underfilled] it should shift. IF it does not, I recommend that you take it to an AAMCO repair shop if you have one near by. Otherwise any transmission shop since most transmission problems require special tools and special training. Joe

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Dean Ott

• 46 Answers
• Posted on Jul 21, 2012

SOURCE: changed trans fluid in 2002 chevy blazer and now it wont shift into overdrive properly without hesitation

If it had lots of miles on the trans fluid befor you changed it that fluids additives broke down long ago and wore out most of the fiber material in your trans,,its a problem with alot of gm makes ,unfortunatly you now need to rebuild at least a portion of the trans