Possible Causes:
* Broken or worn regulator cable: This is the most common culprit. The cable that winds around the regulator spool to raise and lower the window can break, fray, or become detached.
* Worn regulator motor: The electric motor that drives the regulator may be weak or failing. It might be able to overcome the inertia of the window going down (gravity assists), but lack the power to lift it.
* Stripped gears or broken regulator components: Inside the regulator assembly, there are gears that mesh and transfer power from the motor to the cable. These gears can strip, break, or become misaligned.
* Bad window switch: While less likely if the window goes down, a faulty switch could be sending an inconsistent signal, preventing the upward movement. However, this is less probable if the motor seems to be working in one direction.
* Power supply issue (fuse or wiring): Check the fuse for the rear window motor (consult your owner's manual). Look for any broken or corroded wiring in the harness leading to the motor. Less likely if it goes down, but worth ruling out.
Repair Steps:
1. Safety First: Disconnect the negative battery terminal before starting any work to avoid electrical shocks.
2. Inspect the Window: Check for any obvious obstructions preventing the window from going up. Something might be jamming the mechanism.
3. Check the Fuse: Locate the fuse for the rear window motor in the fuse box (your owner's manual will show you the location and which fuse to check). Replace it if it's blown.
4. Test the Switch: Try using the window switch multiple times. If it still doesn't go up, move on to the next steps.
5. Access the Window Regulator: This is the most involved part. You'll need to remove the interior trim panel surrounding the rear window to access the regulator mechanism. This involves removing screws, possibly clips, and potentially prying carefully to avoid breaking the plastic. YouTube videos for your specific year and model Trooper are invaluable here. Search for "1992 Isuzu Trooper rear window regulator replacement."
6. Inspect the Regulator: Once you have access, carefully inspect the regulator cable for breaks or fraying. Look for stripped gears or other signs of damage within the regulator assembly itself.
7. Repair or Replace:
* Cable Repair: Sometimes a broken cable can be spliced and reconnected, but this is a tricky repair and may not last long.
* Regulator Repair: Repairing stripped gears or broken components is usually not feasible; it's often more cost-effective to replace the entire regulator assembly.
* Motor Replacement: If you suspect the motor itself, testing it with a multimeter to verify its operation is a good step before replacement.
8. Reassembly: Carefully reassemble everything, making sure all the trim pieces are securely attached.
9. Test the Window: Reconnect the battery and test the window.
Important Considerations:
* Parts: Finding a replacement regulator for a 1992 Isuzu Trooper might require some searching. Online auto parts retailers or junkyards are good options.
* Difficulty: Replacing the regulator is not a simple job; it requires some mechanical aptitude and patience. If you're uncomfortable working on car parts, it's best to take it to a mechanic.
* YouTube Tutorials: Search YouTube for "1992 Isuzu Trooper rear window regulator replacement" to find visual guides that can significantly help.
By systematically checking each component, you should be able to pinpoint the cause of the malfunction and get your rear window working properly again. Remember to consult a repair manual or online resources specific to your vehicle's year and model for detailed instructions and diagrams.
