1. Identify the Problem Area:
* Latch itself: The most common culprit. The latch might be broken, bent, or worn. This includes the striker plate (the metal piece on the door frame the latch engages with).
* Door Striker: The striker plate might be loose, bent, or damaged, preventing proper engagement with the latch.
* Door hinges: While less likely if the door *shuts*, excessively worn hinges could allow the door to shift slightly, preventing the latch from engaging.
* Rods and linkages: Internal rods and linkages connect the handle to the latch. These could be broken, disconnected, or bent.
* Lock mechanism: A malfunctioning lock mechanism could interfere with the latching process.
2. Troubleshooting Steps:
* Visual Inspection: Carefully examine the latch mechanism, striker plate, and hinges. Look for any obvious damage, looseness, or misalignment.
* Check the Striker Plate: Ensure the striker plate is firmly secured to the door frame. If loose, tighten the screws. If bent, try to gently straighten it with pliers. If severely damaged, it needs replacing.
* Operate the Latch: Try manually operating the latch with the door slightly ajar. See if you can feel any binding or resistance. Listen for any unusual clicking or grinding sounds.
* Test the Door Handle: Make sure the inside and outside door handles operate smoothly and fully actuate the latch mechanism.
* Check the Latch Adjustment: Some latches have adjustment screws. These allow you to fine-tune the position of the latch bolt. This might be necessary if the striker plate is slightly misaligned. (Refer to a repair manual for your specific Ranger model if attempting this).
* Inspect the linkage: If you're comfortable removing the interior door panel (it's usually held on by screws), you can examine the linkage rods. Look for any broken or disconnected components.
3. Repair/Replacement:
* Replace the Latch Assembly: If the latch is broken or worn beyond repair, you'll need to replace the entire latch assembly. This is usually the most effective solution. You'll need to get the correct part for your specific year and model Ranger. Auto parts stores (both online and brick-and-mortar) can help with this.
* Replace the Striker Plate: If the striker plate is damaged, replace it. These are relatively inexpensive and easy to replace.
* Repair or Replace Hinges: If the hinges are excessively worn, they might need lubrication, tightening, or even replacement.
* Repair Linkage: If a linkage rod is broken or disconnected, you'll need to repair or replace it. This usually involves removing the interior door panel.
Important Notes:
* Repair Manual: A repair manual specific to your 1989 Ford Ranger XLT will be incredibly helpful. It will show you diagrams and provide detailed instructions for disassembling and reassembling the door latch mechanism. You can find these online or at auto parts stores.
* Safety First: Always disconnect the battery's negative terminal before working on any electrical components.
* Professional Help: If you're not comfortable working on car repairs, it's best to take your Ranger to a qualified mechanic.
Remember to replace any parts with OEM (Original Equipment Manufacturer) parts or high-quality aftermarket equivalents for the best fit and function. A poorly fitting part can lead to more problems down the road.
