How to Replace the Alternator on a 2017 GMC Sierra 1500
Step-by-step instructions with tools, parts, torque specs, and safety tips for 2014, 2015, 2016, 2017, 2018
How to Replace the Alternator on a 2017 GMC Sierra 1500
Step-by-step instructions with tools, parts, torque specs, and safety tips for 2014, 2015, 2016, 2017, 2018
🔧 Alternator - Replacement
The alternator charges the battery and powers the electrical system while the engine runs. If it fails, you may see battery warnings, dim lights, or a dead battery even after a jump start. This job is straightforward, but the belt system and battery cables need careful handling.
Difficulty Level: Intermediate | Estimated Time: 1.5-2.5 hours
⚠️ Safety & Precautions
- Disconnect the negative battery cable before touching the alternator wiring.
- Keep hands, tools, and clothing away from the belt and pulleys.
- The engine bay may be hot. Let it cool before starting.
- On 4WD trucks, access can be tight around the front of the engine.
- Assumption: No aftermarket accessories or altered belt routing are installed.
🔧 Required Tools
You'll need the following tools for this repair:
- 10mm wrench
- 10mm socket
- 13mm socket
- 15mm socket
- Ratchet
- Long-handled breaker bar
- Belt tensioner tool
- Torque wrench
- Trim clip tool
- Safety glasses
- Mechanic gloves
- Battery terminal protector spray
🔩 Required Parts
HowToo sells all the parts you need for this repair:
- Alternator - Qty: 1
- Serpentine belt - Qty: 1
- Battery terminal cleaning pads - Qty: 1
- Alternator mounting hardware - Qty: 1 set
📋 Before You Begin
- Park on level ground and set the parking brake.
- Turn the ignition off and remove the key or fob from the vehicle.
- Disconnect the negative battery cable first, using a 10mm wrench.
- If the belt is cracked, glazed, or noisy, replace it while you are in there.
🔨 Step-by-Step Instructions
Follow these steps in order:
Step 1: Disconnect the battery
- Use a 10mm wrench to loosen the negative battery terminal.
- Lift the cable off the battery and secure it so it cannot spring back.
Step 2: Remove the intake duct if needed
- Use a trim clip tool to remove any clips holding the air intake duct or resonator.
- Lift the duct out of the way to open up access to the front of the engine.
- Take a quick photo before removing anything.
Step 3: Release belt tension
- Use a belt tensioner tool on the serpentine belt tensioner.
- Rotate the tensioner to unload the belt, then slip the belt off the alternator pulley.
- Slowly release the tensioner.
Step 4: Remove the alternator electrical connections
- Use a 10mm socket to remove the alternator B+ cable nut.
- Pull the main charging cable off the alternator stud.
- Unplug the small electrical connector by pressing the lock tab and pulling straight out.
- Do not pull on the wires.
Step 5: Remove the alternator
- Use a 15mm socket and ratchet to remove the alternator mounting bolts.
- Support the alternator with one hand while removing the last bolt.
- Lift the alternator out of the engine bay.
- Torque on installation: Alternator mounting bolts to 50 Nm (37 ft-lbs).
Step 6: Install the new alternator
- Set the new alternator in place and start both mounting bolts by hand.
- Use a 15mm socket to tighten the bolts evenly.
- Reconnect the electrical connector until it clicks.
- Install the B+ cable with a 10mm socket.
- Torque the B+ terminal nut to 15 Nm (11 ft-lbs).
- Torque the mounting bolts to 50 Nm (37 ft-lbs).
Step 7: Reinstall the serpentine belt
- Use the belt tensioner tool to rotate the tensioner again.
- Route the belt back onto the alternator pulley, then make sure it is seated in every pulley groove.
- Slowly release the tensioner.
- Check the belt ribs line up in every groove.
Step 8: Reinstall intake parts and reconnect power
- Reinstall any intake ducting or clips using the trim clip tool.
- Reconnect the negative battery cable with a 10mm wrench.
- Tighten the terminal snugly, then apply battery terminal protector spray.
✅ After Repair
- Start the engine and verify the battery warning light is off.
- Listen for belt squeal or pulley noise.
- Check that all electrical loads work normally: headlights, blower motor, radio, and windows.
- If you have a multimeter, verify charging voltage is about 13.5-14.8 volts at idle.
- Inspect the belt after a short drive to confirm it is tracking correctly.
💰 DIY vs Shop Cost
Shop Cost: $550-$950 (parts + labor)
DIY Cost: $220-$420 (parts only)
You Save: $330-$530 by doing it yourself!
Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-2.5 hours.
🎯 Ready to get started?
HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.
















