1. Fuses: Start with the simplest. Check the fuse box for any blown fuses related to the power windows. Your owner's manual will show you which fuses control the windows.
2. Switch: The window switch itself is a common culprit. These switches can wear out internally, especially after 50+ years. Try testing each switch individually and see if you can pinpoint which one(s) is/are malfunctioning. Sometimes, carefully cleaning the switch contacts with electrical contact cleaner might revive it.
3. Wiring: The wiring harnesses in a car that age can become brittle, corroded, or broken. Check the wiring running from the switches to the window motors for any damage, loose connections, or broken wires. Pay close attention to areas where wires bend or flex frequently.
4. Window Regulator: This is the mechanical part that moves the window. It consists of a motor, gears, and cables. Common problems include:
* Motor Failure: The motor itself might have burned out. This is often a result of a seized regulator or excessive strain.
* Gear Failure: The gears can strip or break, preventing the motor from turning the regulator.
* Cable Issues: The cables that connect the motor to the window can break or come off the pulleys.
* Binding: The regulator itself may be binding due to rust, dirt, or debris. This often requires disassembly and cleaning or replacement.
5. Relay (if applicable): Some systems might use a relay to control the power to the window motors. Check this if there's a separate relay for the power windows (consult your wiring diagram).
6. Vacuum System (less likely, but possible): While less common in later models, some very early power window systems used vacuum instead of electricity. If yours is this type, check the vacuum lines for leaks or blockages. However, 1967 Cadillacs were almost certainly electrical.
7. Ground: A poor ground connection can prevent the system from functioning correctly. Make sure all ground wires are securely connected.
Troubleshooting Steps:
1. Visual Inspection: Start by carefully examining all the components mentioned above. Look for obvious signs of damage.
2. Fuse Check: Always check the fuses first.
3. Switch Test: Try each switch individually.
4. Wiring Inspection: Trace the wiring from the switches to the motors. Use a multimeter to check for continuity if you have one.
5. Motor Test (Advanced): If you suspect a motor problem, you can test the motor directly with a 12V power source (with caution!). However, this requires some electrical knowledge.
If you're not comfortable working with car electrics, it's best to take your car to a qualified mechanic specializing in classic cars. They have the experience and tools to diagnose and repair the problem efficiently. Remember that replacing parts on a classic car can be more expensive due to the age and availability of components.
