1. Check the Switch:
* Isolate the Switch: Try operating the other windows. If they work fine, it's less likely a problem with the main control panel. If *all* the windows are malfunctioning, the problem likely *is* the main control panel or a more central electrical issue. If only the rear driver's window is affected, it's very likely the switch or its wiring.
* Test the Switch (Advanced): This requires a multimeter. You need to check for continuity between the switch terminals when you actuate it. If there's no continuity, the switch is faulty. This step requires some electrical knowledge and care.
2. Check the Wiring (Again, but more specifically):
* Trace the Wires: Carefully trace the wires from the main control panel *specifically to the rear driver's side window motor*. Look for any breaks, chafing, or corrosion. This is often the culprit in older cars. Pay close attention to where the wires go through the door frame, as this area is prone to damage.
* Door Harness: The wiring harness that runs through the flexible rubber boot in the door is a common failure point. Inspect this very carefully for cracks or broken wires.
3. Inspect the Window Regulator and Motor:
* Access the Regulator: You'll need to remove the door panel (usually involves removing screws and carefully prying it loose). Once the panel is off, you can visually inspect the regulator mechanism for any broken parts, binding, or anything obviously out of place.
* Test the Motor (Advanced): If you're comfortable with basic electrical work, you can use your multimeter to test the motor directly. You'll need to carefully disconnect the wires from the motor and then check for continuity and resistance to see if the motor is functioning correctly. Be cautious, as working with car electrical systems can be dangerous. A bad motor is a common cause of this problem.
4. Possible Additional Issues:
* Ground: A poor ground connection can prevent the motor from working. Check the ground wire connected to the motor and regulator assembly for corrosion or a loose connection.
* Wiring connector: There may be an issue with the connector itself at the motor. The wires might be loose or corroded within the connector.
Important Notes:
* Safety First: Disconnect the battery negative terminal before working with any electrical components in your car.
* Repair Manual: A repair manual specific to your 1982 Oldsmobile Delta 88 will be invaluable in this process. It will show you how to remove the door panel and other parts, as well as wiring diagrams.
* Professional Help: If you're not comfortable working with car electrical systems, take it to a qualified mechanic. Incorrect wiring can cause further damage.
Start with the simplest checks (switch and wiring inspection) before moving to more involved tasks (testing the motor and regulator). The problem is most likely a broken wire, a faulty switch, or a bad motor. Systematically checking these will help you pinpoint the fault.
