1. Troubleshooting Steps:
* Visual Inspection:
* Carefully inspect the rear window for any signs of damage to the defroster lines. Even a tiny crack can disrupt the circuit.
* Look for any corrosion or build-up on the metal contact points where the defroster lines connect to the rear window.
* Continuity Test:
* Using a multimeter, check for continuity across the entire length of each defroster line. This will confirm that the elements are indeed intact.
* Voltage Check:
* You've already checked the voltage at the fuse, but confirm that you're getting the proper voltage at the defroster lines themselves when the switch is turned on.
* If the voltage is present at the fuse but not at the lines, this likely points to a problem with the wiring itself.
* Check the Defroster Switch:
* The switch itself can become faulty and prevent power from reaching the defroster lines.
* You can use a multimeter to test the switch for continuity when it's in the "on" position. If there's no continuity, replace the switch.
* Check for Ground Connection:
* A poor ground connection can prevent proper operation of the defroster.
* Inspect the ground wire connected to the defroster circuit, and ensure it's clean and making good contact.
2. Potential Causes and Solutions:
* Broken Defroster Lines:
* This is the most common cause, but you've already ruled it out.
* Corrosion or Dirt on Contact Points:
* Clean the contact points with a wire brush or sandpaper.
* Defective Wiring:
* If the voltage drops off somewhere between the fuse and the defroster lines, you'll need to trace the wiring and find the faulty section. This may require removing interior trim panels.
* Faulty Defroster Switch:
* As mentioned above, a faulty switch can be the culprit. Replace it if necessary.
* Faulty Ground:
* Check the ground wire and clean or replace it as needed.
* Defroster Control Module:
* A malfunctioning defroster control module could be interrupting the signal to the defroster. This is less common but worth investigating if all other checks have been made.
Important Notes:
* Safety First: Be careful when working with electricity. Disconnect the battery before working on any electrical components.
* Professional Help: If you're not comfortable troubleshooting electrical systems, it's best to take your Alero to a qualified mechanic.
Let me know if you have any further questions. Good luck with the repair!
