Buzz
The alternator in your vehicle is responsible for supplying power to recharge the battery and operate its electrical components. If you notice symptoms such as dimming headlights or interior lights, it's advisable to have your alternator checked for free at most auto parts stores. If it's unable to generate sufficient current to maintain your battery's charge and keep your car running, it will require rebuilding or replacement.
Procedures
Disconnecting the Alternator
Park the vehicle on a level, flat surface. Safety is of utmost importance whenever you're undertaking work on your car. Ensure the surface is suitable for the task at hand, especially if you need to elevate the vehicle. It's crucial to have it parked securely on an even, flat area.
- Working on a level surface makes the job easier, even if you don't require jacking up the vehicle.
- Ensure the vehicle is securely parked, or engage the parking brake (if your car has a manual transmission).
Disconnect the battery. Locate the appropriate socket to loosen the bolt securing the cable on the negative terminal of the battery, marked with a visible (-) sign. Once loosened, slide the cable off the terminal to disconnect the battery. Prioritize safety by always disconnecting the battery before working in the engine bay of a vehicle.
- Working on the alternator without disconnecting the battery could result in electric shock or damage to the vehicle.
- You can keep the positive cable attached.
Elevate the vehicle if necessary. Follow the path of the serpentine or accessory belts to locate the alternator within the engine bay. Depending on your vehicle, it may be positioned at the top nearest to you, or it might be situated on one of the sides, making access challenging. If accessing it from the engine bay proves difficult, you'll need to lift the vehicle.
- Ensure the parking brake is engaged and the wheels are properly blocked before lifting the vehicle.
- Once elevated, place jack stands beneath the vehicle for added safety.
Detach the main power cable from the alternator. Identify the main power cable, typically a thick cable connected to the alternator originating from the battery. Depending on the available space in your vehicle, you may use a ratchet or, in some cases, only an open-ended wrench. Unscrew the bolt securing it in place and remove it from its connection point.
- The bolts usually require standard-sized sockets or wrenches in American-made vehicles, and metric in most foreign applications.
- The sole other cable linked to the alternator connects to a harness, making it easy to distinguish.
- Set the bolt aside in a secure location until you install the new alternator.
Release the safety clip connecting the wiring harness. The sole additional wiring entering the alternator is the control harness. Use your finger or a flat-head screwdriver to release the clip securing the harness, then gently separate them.
- Exercise caution if using a screwdriver to reach difficult clips to avoid damaging the plastic.
- Tuck the loose wire aside to prevent it from catching on the alternator during removal.
Removing the Old Alternator
Release tension on the belt using the auto-tensioner (if available). Some vehicles employ the alternator for belt tension, while others utilize an auto-tensioner pulley. Insert a breaker bar's square drive into the auto-tensioner pulley hole and apply clockwise pressure to release belt tension.
- To determine if your vehicle uses an auto-tensioner, inspect the alternator mounting bracket: if the bolts can move sideways within the bracket, there's no auto-tensioner.
- Before releasing the auto-tensioner, remove the belt from the alternator pulley.
- Prior to any adjustments, take photos of the belt setup to ensure correct reassembly.
- In certain vehicles, assistance may be required to release belt tension while removing it.
Loosen alternator bolts if no auto-tensioner is present. In vehicles lacking an auto-tensioner, you can relieve belt tension by loosening the two bolts securing the alternator to the engine. Typically, a 14mm or 1⁄2 inch (1.3 cm) socket is used, but other sizes may be necessary.
- Loosening the bolts causes the alternator to slide within the bracket under belt tension.
- Only loosen the bolts; do not remove them!
- If the belt is undamaged, removal may be unnecessary.
Examine the serpentine belt for wear. Check for glossing or glazing (shiny areas) along the edges and underside of the belt. Inspect both sides for signs of cracking.
- If any issues are detected, the belt requires replacement.
Extract the alternator from the engine compartment. Once the belt is removed from the alternator pulley and the wires are disconnected, the alternator should be easily removed.
- Maneuvering may be necessary to remove the alternator from obstacles.
- Note the removal process to aid in installing the new alternator.
Compare the new alternator with the old one. Before installation, place the new alternator beside the removed one. Ensure the mounting holes and wire connectors align and that both parts are of equal size.
- Despite providing specific details during purchase, this step verifies the correct part was supplied.
- If discrepancies arise, return the new alternator to the store for the correct replacement.
Installing the New Alternator
Position the new alternator. You may need to maneuver the alternator to fit it snugly back into place within the crowded engine bay. Ensure to keep loose wires or the serpentine belt clear as you reposition it.
- Take care not to trap any wiring behind the alternator during installation.
- Watch for the serpentine belt to avoid damaging it while placing the alternator.
Insert and secure the mounting bolts. Guide the mounting bolts through the alternator and into the mounting bracket. Hand tighten them until snug. For vehicles with an auto-tensioner pulley, fully tighten the bolts now; otherwise, keep them loose.
- If there's no auto-tensioner, you'll need to adjust belt tension using the alternator later.
- Ensure the bolts are tight enough to hold the alternator in place but still allow lateral movement in the bracket.
Install the belt onto the new alternator pulley. Either fit the new belt or reinstall the old one, ensuring it passes through all necessary pulleys. If unsure, refer to previously taken photos or diagrams in the engine bay. The belt must properly engage with all components it powers.
- Keep the tensioner loose with pressure on the ratchet. Once the belt is correctly seated, gradually release the ratchet, allowing the tensioner to apply tension to the belt.
- If no diagram is available in the engine bay, consult the vehicle owner's manual or the manufacturer's website.
Adjust alternator tension using a pry bar if needed. For vehicles lacking an auto-tensioner pulley, apply pressure to the alternator with a large screwdriver or pry bar until the belt is taut. Insert the pry bar between the alternator and the engine, pushing the alternator outward from the engine.
- Exercise caution to avoid pinching or cutting any wires with the screwdriver or pry bar.
- Continuous pressure may be required until bolts are tightened, possibly with assistance from another person.
Secure the bolts and adjust the belt. Apply tension to the belt using the alternator and pry bar. Then, use a ratchet and the appropriate socket to fully tighten the two mounting bolts, ensuring the alternator maintains belt tension.
- Ensure the serpentine belt has less than an inch of play once installed.
- If the belt is slightly loose, loosen the bolts, apply pressure with the pry bar, and retighten.
- Refer to your belt photos to verify correct positioning.
Reattach the power cable and monitoring harness. Connect the wire harness and secure the main power cable bolt to the alternator in the same manner as before. They should align precisely as with the old alternator.
- Ensure the primary power cable is securely fastened to the new alternator.
- Listen for an audible “click” to confirm the wiring harness is properly seated.
Reconnect the battery. With the new alternator installed, the final step is to reconnect the negative battery lead. Tighten it securely to prevent loosening while driving.
- If the battery is depleted, consider jump-starting it.
- If the vehicle is elevated, remove the jack stands and lower it.
Useful Tips
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Many auto parts stores offer serpentine belt tools for a small refundable deposit.
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Document your disassembly with a digital camera to aid reassembly. This facilitates remembering the sequence.
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If locating the serpentine belt tensioner is challenging, consult the engine bay diagram for assistance.
Cautions
- When reinstalling the old bolts onto the new alternator, refrain from tightening them until all are in place.
- Always allow the engine to cool before commencing work nearby to avoid burns.
- Disconnect the negative battery cable before performing any electrical work on your vehicle to prevent electrical system short-circuits and electronics damage.
