electrical

Starter Solenoid

for 2021 Ford F-150 3.5L V6 EcoBoost · 4WD

Difficulty

Moderate

Time

2.4 h

Tools

Steps

This procedure covers the removal and replacement of the starter solenoid on a 2021-2024 Ford F-150 with the 3.5L EcoBoost V6 engine. The solenoid is integrated into the starter assembly and requires starter removal.

Warnings

⚠️Disconnect the negative battery cable and wait 2 minutes before beginning work to prevent accidental starter engagement and electrical shock

⚠The starter weighs approximately 12 lbs and is mounted at an awkward angle. Support it properly during removal to prevent injury or damage

⚠Work only on a cool engine. The starter is located near the exhaust manifold and turbocharger, which retain heat for extended periods

ℹ️On the 3.5L EcoBoost, the starter solenoid is not serviceable separately from the starter assembly and requires complete starter replacement

Tools required

10mm socket and ratchetEssential

13mm socket and ratchetEssential

15mm socket and ratchetEssential

18mm wrenchEssential

Torque wrench (5-60 Nm range)Essential

Battery terminal puller

Wire brush

Jack and jack standsEssential

Wheel chocksEssential

Extension set (3-inch and 6-inch)Essential

Universal joint socket adapter

Penetrating oil

Electrical contact cleaner

Parts

Starter assembly with integrated solenoid × 1 — Motorcraft SA-1174-RM or equivalent
Anti-seize compound × 1 — Use high-temperature anti-seize

Preparation

Park vehicle on level surface and engage parking brake
Place wheel chocks behind rear wheels
Allow engine to cool completely if recently operated (minimum 2 hours)
Raise front of vehicle and support securely on jack stands
Remove engine splash shield if equipped (10mm fasteners)
Disconnect negative battery cable and secure away from battery post

Procedure

1
Disconnect battery and allow capacitor discharge
Loosen the 10mm nut on the negative battery terminal and remove the cable. Secure the cable away from the battery post to prevent accidental contact. Wait a minimum of 2 minutes to allow vehicle electrical systems to discharge.
Torque spec
Battery Terminal Bolts6 Nm (4 lb-ft)
2
Access starter from below vehicle
Position yourself under the front passenger side of the vehicle. Locate the starter motor mounted to the transmission bellhousing between the engine and transmission. The starter is positioned with the solenoid facing toward the front of the vehicle.
3
Disconnect starter electrical connections
Locate the two electrical connections on the starter solenoid. Remove the protective rubber cap from the battery cable terminal. Using an 18mm wrench, remove the nut securing the battery positive cable to the solenoid stud. Remove the cable and secure it away from the starter. Disconnect the smaller trigger wire connector by pressing the release tab and pulling straight off.
⚠The battery cable terminal carries full battery voltage. Ensure it does not contact any grounded surfaces during removal
Torque spec
Battery Terminal Bolts6 Nm (4 lb-ft)
4
Remove starter heat shield if equipped
If your vehicle is equipped with a starter heat shield, remove the mounting bolts using a 10mm socket. The heat shield may be stuck due to heat cycling; gently pry if necessary. Set the shield aside for reinstallation.
5
Remove upper starter mounting bolt
Using a 15mm socket with a long extension and possibly a universal joint adapter, remove the upper starter mounting bolt. This bolt is accessed from below and may require maneuvering around surrounding components. The bolt threads into the transmission bellhousing.
ℹ️The upper bolt may be difficult to access due to limited clearance. A wobble extension or universal joint is highly recommended
Torque spec
Mounting Bolts39 Nm (29 lb-ft)
6
Remove lower starter mounting bolt
Using a 15mm socket with extension, remove the lower starter mounting bolt. This bolt is typically more accessible than the upper bolt. Support the starter with one hand as you remove the final bolt to prevent it from falling.
⚠The starter will become free once this bolt is removed. Ensure you have a secure grip or have positioned a support underneath
Torque spec
Mounting Bolts39 Nm (29 lb-ft)
7
Remove starter assembly
With both mounting bolts removed, carefully work the starter assembly out of the bellhousing. You may need to rotate and angle the starter to clear surrounding components including the exhaust and turbo plumbing. Guide the electrical connections through as you remove the unit. Lower the starter and remove from under the vehicle.
8
Inspect and clean mounting surfaces
Inspect the starter mounting surface on the transmission bellhousing for debris, corrosion, or damage. Clean the mounting surface with a wire brush if necessary. Verify the alignment dowel pin (if equipped) is present and undamaged. Inspect the electrical terminals for corrosion and clean with electrical contact cleaner if needed.
9
Prepare new starter for installation
Remove the new starter from packaging and verify it matches the original unit exactly, including electrical terminal configuration and mounting bolt pattern. Apply a thin coat of anti-seize compound to the mounting bolt threads (not the bolt heads). Verify the solenoid plunger moves freely by manually pressing it.
10
Install new starter assembly
Position yourself under the vehicle with the new starter. Guide the electrical connection area through first, then angle the starter into position against the bellhousing. Align the mounting holes and ensure the starter seats flush against the transmission. Start both mounting bolts by hand to ensure proper thread engagement before tightening.
⚠Do not force the starter into position. It should seat naturally when properly aligned with the dowel pin and mounting holes
11
Torque starter mounting bolts
Using a torque wrench with 15mm socket, tighten the upper starter mounting bolt to specification. Then torque the lower mounting bolt to the same specification. Tighten in this sequence to ensure even seating of the starter against the bellhousing.
Torque spec
Mounting Bolts39 Nm (29 lb-ft)
12
Reconnect starter electrical connections
Connect the small trigger wire to the solenoid by pushing the connector firmly onto the terminal post until it clicks into place. Position the battery positive cable over the solenoid stud. Install the terminal nut and tighten to specification using an 18mm wrench and torque wrench. Replace the protective rubber cap over the terminal connection.
Torque spec
Battery Terminal Bolts6 Nm (4 lb-ft)
13
Reinstall heat shield and undercar components
If a heat shield was removed, position it back over the starter and install the mounting bolts, tightening securely. Reinstall the engine splash shield if it was removed. Verify all tools and parts have been removed from under the vehicle before lowering.
14
Reconnect battery and perform system check
Reconnect the negative battery cable to the battery terminal. Tighten the terminal bolt to specification using a 10mm socket and torque wrench. Ensure the connection is secure and the cable cannot rotate on the terminal post.
Torque spec
Battery Terminal Bolts6 Nm (4 lb-ft)

Reassembly

Verify all electrical connections are secure and properly routed
Confirm starter mounting bolts are torqued to specification
Ensure no tools or parts remain in the engine bay or under vehicle
Double-check that battery terminals are tight and corrosion-free

Verification

Turn the ignition key to the START position and verify the engine cranks normally with no grinding or unusual noises
Verify the starter disengages immediately when the key is released to the RUN position
Check that there are no warning lights on the instrument cluster related to the charging system
Start the engine 3-4 times to confirm consistent operation
Listen for any abnormal clicking or chattering from the starter solenoid during cranking
Verify no electrical burning smell is present after several start cycles
Inspect underneath the vehicle for any loose components or fluid leaks disturbed during the repair