1. Fuses:
* Check the fuse box(es): Your Trailblazer likely has multiple fuse boxes, one under the hood and another inside the cabin (often under the dash). Consult your owner's manual to locate them and identify the fuses for the blower motor and wipers. Look for blown fuses (broken filament). Replace any blown fuses with the correct amperage. If a fuse blows immediately after replacement, you have a short circuit somewhere in the system and should proceed cautiously.
2. Relays:
* Locate the relays: Relays are electromechanical switches that control higher-power components like the blower motor and wipers. Your owner's manual or online resources should show their location (often near the fuse boxes). Visually inspect the relays for any damage. A simple test is to swap suspected relays with similar-looking ones (if possible, and *only* if you know what you are doing) to see if the problem moves. If you aren't comfortable with this, it's best left to a mechanic.
3. Wiper Motor/Blower Motor:
* Wiper Motor: The wiper motor itself could be faulty. This requires more advanced diagnostics to determine if the motor is getting power but not turning.
* Blower Motor: Similar to the wiper motor, the blower motor might be failing. Sometimes you can hear a clicking sound if the motor is trying to engage but can't. Accessing and testing this often requires some disassembly.
4. Switches:
* Wiper Switch: The switch stalk on the steering column could be defective. If other functions on the stalk (like intermittent wipers) work, the problem might be internal to the switch itself.
* Blower Motor Switch: The switch controlling the blower motor speed could be broken. Testing this usually involves using a multimeter to check for voltage at the switch and at the blower motor.
5. Wiring and Connections:
* Look for damaged wiring: Inspect the wiring harness leading to the wiper motor, blower motor, and switches. Look for broken wires, frayed insulation, or corrosion.
* Check connections: Ensure all connectors are securely plugged in. Corrosion on the connectors can prevent proper electrical contact.
6. Body Control Module (BCM):
* Faulty BCM: The BCM is the brain of many vehicle electrical systems. A malfunctioning BCM can affect various functions, including wipers and blower. This requires advanced diagnostic tools to test the BCM.
Troubleshooting Steps:
1. Start with the simplest checks: Fuses first!
2. Consult your owner's manual: It's your best friend for locating components and understanding the system.
3. Visual inspection: Look for obvious signs of damage to wiring, connectors, and components.
4. Use a multimeter: If you are comfortable with electrical testing, a multimeter can help determine if power is reaching the components.
5. Seek professional help: If you're not comfortable troubleshooting electrical systems, it's best to take your Trailblazer to a qualified mechanic. Improper repairs can lead to further damage or even create safety hazards.
Remember safety first. Disconnect the battery negative terminal before working with any electrical components to avoid shocks.
