Here's what could be wrong:
* Faulty motor: The motor responsible for forward/backward movement is broken or burned out. This is the most likely culprit.
* Wiring issue: A broken wire, loose connection, or short circuit in the wiring harness supplying power to the forward/backward motor. Inspect the wiring carefully.
* Switch problem: While less likely given that up/down works, the switch itself might have an internal failure affecting only the forward/backward control.
* Fuse: Check your owner's manual to see if there's a separate fuse for the power seat, or if it's on a shared circuit. A blown fuse could be the simplest fix.
* Internal mechanism: There might be a mechanical issue within the seat itself (gear, track, etc.) hindering forward/backward movement.
Troubleshooting steps:
1. Check the fuses: This is the easiest and quickest thing to check first.
2. Inspect the wiring: Look for any visible damage to the wires connecting the power seat to the control panel. Pay close attention to the area where the wires enter the seat.
3. Try the seat switch repeatedly: Sometimes a sticky contact can be cleared by repeatedly moving the switch.
4. Test the switch with a multimeter (if you have one): This requires some electrical knowledge, but you could check for continuity and voltage at the switch to confirm it's functioning correctly.
5. Consult a repair manual: A repair manual specific to your 2004 Chevy Trailblazer will give you diagrams of the wiring and the power seat mechanism, making troubleshooting much easier.
6. Take it to a mechanic: If you're not comfortable working with car electrical systems or mechanical repairs, a mechanic will be able to diagnose and repair the issue efficiently.
It's usually not a simple fix, and attempting repairs without the necessary knowledge could cause further damage. Consider the cost of a professional repair versus the risk of making the problem worse before attempting any DIY repairs.
