Tools You'll Likely Need:
* Jack and jack stands (crucial for safety!)
* Wheel chocks
* Lug wrench
* Socket set (metric)
* Ratchet
* Extension(s)
* Possibly a torque wrench
* Penetrating oil (like PB Blaster)
* Clean rags
* New wheel speed sensor (ensure you get the correct one for your vehicle's year, make, model, and wheel position)
Steps:
1. Safety First: Park on a level surface, engage the parking brake firmly, and chock the wheels opposite the one you're working on. Use jack stands to securely lift the vehicle after jacking it up. Never work under a vehicle supported only by a jack.
2. Locate the Sensor: The wheel speed sensor is typically located near the wheel hub, often inside the brake rotor or backing plate. The exact location varies depending on the wheel. Refer to your repair manual for the precise location on your 1999 Safari. It's usually a small, cylindrical sensor with a wire harness attached.
3. Remove the Wheel: Loosen the lug nuts slightly before jacking up the vehicle. Once secured on jack stands, remove the lug nuts completely and carefully remove the wheel.
4. Access the Sensor: This is the most variable step. You might need to:
* Remove the brake caliper: In many cases, you'll need to carefully remove the brake caliper to access the sensor. Support the caliper with a bungee cord or wire to keep it from hanging by the brake line. Do not disconnect the brake line.
* Remove the brake rotor: On some models, the rotor might need to be removed to reach the sensor. If so, use a suitable tool to remove the rotor.
* Remove the backing plate: Sometimes the sensor is behind a backing plate which may need to be removed.
5. Disconnect the Sensor: Carefully unplug the electrical connector from the old sensor.
6. Remove the Old Sensor: The sensor is usually held in place by a bolt or clip. Use the appropriate socket or tool to remove it. Penetrating oil may be helpful if the sensor is stuck.
7. Install the New Sensor: Carefully install the new sensor, ensuring it's seated correctly. Tighten the retaining bolt or clip to the manufacturer's specifications (check your repair manual).
8. Reconnect the Electrical Connector: Plug the electrical connector back onto the new sensor.
9. Reassemble: Carefully reassemble everything in reverse order: replace the rotor (if removed), reinstall the brake caliper, and remount the wheel. Tighten the lug nuts to the proper torque specification (check your repair manual).
10. Lower the Vehicle: Slowly lower the vehicle to the ground using the jack.
11. Test: After reassembly, test drive the vehicle to ensure the ABS system is functioning correctly. You may need a diagnostic scanner to confirm the sensor is working.
Important Considerations:
* ABS System: Wheel speed sensors are critical components of the Anti-lock Braking System (ABS). Incorrect installation or a faulty sensor can impair ABS functionality.
* Torque Specifications: Always refer to your repair manual for the proper torque specifications for all bolts and nuts. Over-tightening can damage components.
* Repair Manual: A repair manual specific to your 1999 Pontiac Safari AWD is highly recommended. It will provide detailed instructions, diagrams, and torque specifications that are crucial for a successful repair. Online resources are available, but a printed manual is usually more convenient.
This is a complex repair. If you're not comfortable working on your vehicle's braking system, it's best to take it to a qualified mechanic. Improper repair could lead to braking problems and safety hazards.
