The problem is more likely to be one of these:
* Internal wiring or motor issue within the seat mechanism: This is the most probable cause. A wire may have broken, a connection may have come loose, or the motor responsible for fore/aft movement might be faulty. This often requires disassembly of the seat to diagnose and repair.
* Faulty switch: While less likely than a mechanical problem inside the seat, the switch itself could be failing in a way that only affects the forward/backward function.
* Control module (less likely): There's a possibility, though less probable, that the control module for the power seats has a problem specifically affecting that axis of movement.
Before you start disassembling anything:
1. Check all other power seat functions meticulously: Make absolutely sure that *all* other adjustments (up/down, lumbar, etc.) are working perfectly. This helps narrow down the possibilities.
2. Try the seat switch multiple times: Sometimes a stuck or intermittent switch can be coaxed back to life with repeated pressing.
What to do next:
Since a blown fuse is improbable, the best next step is to consult a repair manual for your 2004 Trailblazer. This will give you step-by-step instructions on how to access and inspect the power seat mechanism. You'll need to determine if you're comfortable undertaking this repair yourself (it can be somewhat involved) or if you should take it to a mechanic. If you're not mechanically inclined, taking it to a professional is recommended.
