* The Wiper Timer Circuit: The timer isn't a simple on/off switch. It's a more complex electronic circuit that controls the speed of the wiper motor. It uses a resistor network (or similar electronic components) to control the power sent to the motor, which affects the wiping speed and creates the intermittent delay. This circuit is usually housed within the wiper control module, not the motor itself.
* Common Failure Points:
* Faulty Wiper Control Module: This is the most likely culprit. The internal components responsible for timing can fail, leading to erratic operation or no intermittent function at all. The module may have suffered from moisture damage, corrosion, or just plain wear and tear over time.
* Bad Connections: Poor connections within the wiper switch assembly, in the wiring harness to the switch or the motor, or even corrosion at the motor connection can interrupt the signal and prevent the timer from working. These need careful inspection and cleaning or repair.
* Damaged Wiring: Worn or broken wires in the harness can cause intermittent or complete failure. Checking the wiring loom for damage, especially near bends and connectors, is crucial.
* Fuse or Relay: While less common, a blown fuse or a faulty relay could also prevent the timer from functioning.
Troubleshooting Steps:
1. Check the Fuse and Relay: Consult your owner's manual to locate and check the fuse and relay responsible for the wipers. Replace if necessary.
2. Inspect Wiring and Connections: Carefully examine the wiring harness leading to and from the wiper control module (usually under the steering column or dashboard) and the wiper motor. Look for broken wires, corrosion, or loose connections. Clean any corrosion and repair any damage.
3. Test the Wiper Motor Directly (Advanced): With the ignition on, you can try supplying direct power (with the correct voltage and polarity – be extremely careful! Incorrect voltage or polarity can damage the motor) to the wiper motor to see if it works. This isolates the motor from the control circuit. *If it works, the problem is definitively in the control circuit.*
4. Replace the Wiper Control Module: This is usually the most effective solution. You'll need to find a replacement module specifically for your 1999 Buick Century. Ensure you get the correct part number. This may involve dismantling parts of the dashboard or steering column to access it.
Important Note: If you're not comfortable working with car electrical systems, it's best to take your Buick to a qualified mechanic. Improper wiring can lead to further damage. Replacing the control module often requires specialized tools and knowledge.
