This procedure covers removal and replacement of the alternator on a 2015-2020 Ford F-150 with the 3.5L EcoBoost V6 engine, including serpentine belt removal and electrical connections.

Warnings

Tools required

Parts

• Alternator (12V, 230A or 240A depending on configuration) × 1 — Use OEM specification or verify amperage rating
• Serpentine belt (if worn or damaged) × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely (minimum 30 minutes)
3. Open hood and secure with prop rod
4. Photograph or diagram serpentine belt routing for reference
5. Disconnect negative battery terminal and wait 2 minutes for system discharge

Procedure

1. 1

   Remove serpentine belt
   Locate the automatic belt tensioner on the front of the engine. Insert a 3/8" breaker bar or serpentine belt tool into the tensioner pulley square hole. Rotate tensioner clockwise to release belt tension. Slide belt off alternator pulley first, then carefully release tensioner. Remove belt from remaining pulleys and extract from engine bay.
2. 2

   Access alternator electrical connections
   The alternator is located on the passenger side of the engine, mid-height. You may need to reach from above or below depending on your access. Identify the main B+ cable connector (large cable with protective boot) and the smaller electrical connector on the alternator rear housing.
3. 3

   Disconnect alternator electrical connections
   Pull back the rubber protective boot on the B+ terminal. Using a 10mm socket, remove the nut securing the B+ cable to the alternator stud. Remove cable and position it away from the alternator. Press the release tab on the smaller electrical connector and disconnect it from the alternator. Ensure connectors are positioned safely away from work area.
4. 4

   Remove upper alternator mounting bolt
   Locate the upper alternator mounting bolt that passes through the alternator mounting bracket into the engine block. This is typically a 13mm or 15mm bolt head. Remove this bolt completely and set aside. Note the location of any spacers or washers.
   Torque spec

   Alternator Mounting Bolts50 Nm (37 lb-ft)
5. 5

   Remove lower alternator mounting bolt
   Locate the lower alternator mounting bolt, which may be accessed from below or through the wheel well area. This bolt secures the bottom of the alternator to the mounting bracket. Remove this bolt completely. The alternator should now be free to remove.
   ⚠Support the alternator with one hand while removing the final bolt to prevent it from falling
   Torque spec

   Alternator Mounting Bolts50 Nm (37 lb-ft)
6. 6

   Remove alternator from vehicle
   Carefully maneuver the alternator out of its mounting position. You may need to tilt or rotate the alternator to clear surrounding components, hoses, and wiring. Work slowly to avoid damaging nearby components. Remove alternator from engine bay.
7. 7

   Prepare new alternator for installation
   Compare new alternator to old unit to verify correct replacement. Check that mounting bolt holes align and pulley diameter matches. Clean mounting surfaces on engine block and bracket with wire brush if needed. Verify electrical connector types match between old and new alternators.
8. 8

   Install new alternator
   Maneuver new alternator into position, reversing the removal path. Align mounting holes with bracket. Support alternator in position while preparing to install mounting bolts. Ensure no wiring or hoses are pinched behind the alternator.
9. 9

   Install lower mounting bolt
   Insert lower alternator mounting bolt and thread by hand to prevent cross-threading. Once hand-tight, use socket and torque wrench to tighten to specification. Do not fully tighten until upper bolt is also installed finger-tight.
   Torque spec

   Alternator Mounting Bolts50 Nm (37 lb-ft)
10. 10

    Install upper mounting bolt
    Insert upper alternator mounting bolt with any spacers or washers in their original positions. Thread by hand until snug. Once both bolts are hand-tight, torque both mounting bolts to specification in a cross pattern to ensure even seating.
    Torque spec

    Alternator Mounting Bolts50 Nm (37 lb-ft)
11. 11

    Reconnect alternator electrical connections
    Connect the small electrical connector to the alternator until it clicks into place. Position the B+ cable over the alternator stud terminal. Install the nut onto the B+ stud and tighten to specification using a 10mm socket and torque wrench. Slide the rubber protective boot back over the B+ terminal connection.
12. 12

    Install serpentine belt
    Route serpentine belt according to your reference photo or the belt routing diagram on the radiator support. Leave the alternator pulley for last. Using the belt tensioner tool or breaker bar, rotate tensioner clockwise and slip belt onto alternator pulley. Carefully release tensioner to apply proper belt tension. Verify belt is properly seated in all pulley grooves.
13. 13

    Reconnect battery and initial check
    Reconnect negative battery terminal and tighten to specification. Before starting engine, visually verify all electrical connections are secure, belt is properly routed, and no tools remain in engine bay. Check that alternator pulley rotates freely by hand.
    Torque spec

    Battery Terminal Bolts8 Nm (6 lb-ft)

Reassembly

1. Verify serpentine belt is properly seated in all pulley grooves and has correct tension
2. Ensure all electrical connectors are fully engaged with protective boots in place
3. Confirm no tools, rags, or parts remain in engine bay
4. Double-check that both alternator mounting bolts are torqued to specification

Verification

• Start engine and verify no unusual noises from alternator or belt area
• Check that battery warning light on instrument cluster illuminates during key-on and extinguishes after engine start
• Using a multimeter, verify charging system voltage at battery terminals is between 13.5-14.5 volts at idle with engine at operating temperature
• Turn on electrical loads (headlights, HVAC, radio) and verify voltage remains in acceptable range
• Rev engine to 2000 RPM and confirm voltage does not exceed 15 volts
• Inspect for any belt slippage, squealing, or abnormal vibration during operation
• Verify all warning lights are off and no new trouble codes are present

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