1. The Latch Mechanism Itself:
* Broken or Bent Latch Bolt: This is the most common issue. The bolt that actually engages with the striker plate on the door frame might be broken, bent, or jammed. You'll need to remove the door panel to inspect it. Often, the bolt is simply sticking and requires lubrication or careful adjustment.
* Worn or Damaged Latch Components: Internal parts of the latch mechanism itself might be worn, broken, or out of alignment. This could include springs, levers, or the receiving portion of the latch mechanism. Again, panel removal and inspection are necessary.
* Rod Linkage Problems (within the latch): Even though the rods *seem* to be working, there might be a broken or disconnected linkage *inside* the latch mechanism itself. This often requires careful disassembly and examination.
2. The Striker Plate:
* Bent or Damaged Striker Plate: The metal plate on the door frame that the latch bolt engages with might be bent out of alignment, preventing the bolt from fully retracting. This is easily checked visually. A slight adjustment or replacement might be needed.
* Loose Striker Plate: The striker plate might be loose or even pulled out from the door frame, causing the bolt to miss its target.
3. Rod Adjustment/Binding:
* Rod Binding: Despite seeming functional, the rods might be binding or catching somewhere along their path. Check for any kinks, rust, or areas where the rods rub against other parts of the door mechanism. Lubrication might help here.
Troubleshooting and Repair Steps:
1. Remove the Door Panel: This is crucial for accessing the latch mechanism and rods. There are numerous online tutorials specific to 1989 Chevy S10 door panel removal. Search YouTube for "1989 Chevy S10 door panel removal" for visual guidance.
2. Inspect the Latch Mechanism: Once the panel is off, carefully examine the latch mechanism for any obvious damage, wear, or misalignment. Look at the latch bolt's movement specifically.
3. Check the Striker Plate: Visually inspect the striker plate for damage or looseness.
4. Operate the Mechanism Manually: With the panel removed, try manually operating the latch bolt using the internal linkage. This helps determine if the problem is within the latch itself or the connecting rods.
5. Lubricate Moving Parts: Use a penetrating lubricant (like WD-40 initially, then a lithium-based grease for long-term lubrication) on all moving parts of the latch and rods.
6. Adjust Rod Linkage: If necessary, carefully adjust the rod linkages to ensure proper engagement. Be cautious not to bend or damage them.
7. Replace Parts: If any parts are broken or beyond repair, they'll need to be replaced. You can find replacement parts at auto parts stores, online retailers, or possibly salvage yards.
Important Considerations:
* Safety First: Always disconnect the battery's negative terminal before working with any electrical components in your vehicle.
* Take Pictures: Before disassembling anything, take detailed pictures to aid in reassembly.
* Patience: This repair can be time-consuming and requires patience and careful attention to detail.
If you're not comfortable working on car mechanics, it's best to take your S10 to a qualified mechanic. The cost of professional repair is likely less than the cost of damaged parts or further issues caused by an unsuccessful DIY attempt.
