how to fix a Ford Mustang S550 (2015-2023) that won’t start

Solution

1. Preparation

• Gather tools and materials.
• Disconnect the battery negative terminal to avoid electrical shorts.
• Tools required: Multimeter, socket set, OBD-II scanner, wire brush (for cleaning), safety gloves, and safety goggles.

2. Battery Inspection and Replacement

• Inspect Battery Health

  • Use a multimeter to check the battery voltage.
  • If the voltage is below 12.4 volts, proceed to jump-start the vehicle or replace the battery.

• Clean Battery Terminals

  • Remove the battery terminals (negative first, then positive).
  • Clean the terminals and cable ends with a wire brush until shiny.
  • Reattach the terminals, ensuring a tight fit.

• Replace the Battery (if necessary)

  • Remove the old battery using a socket set.
  • Install the new battery by reversing the removal process.
  • Connect positive terminal first, then negative.

3. Starter Motor Inspection and Replacement

• Check Starter Connections

  • Inspect wiring at the starter for damage or corrosion.
  • Ensure connections are tight.

• Test the Starter

  • If the battery is good, test the starter motor by applying direct power to it.
  • If it doesn’t engage, replace the starter motor.

• Replace Starter Motor (if necessary)

  • Disconnect wiring from the starter.
  • Remove mounting bolts using a socket set.
  • Install the new starter motor and tighten bolts to manufacturer specifications.

4. Ignition Switch Inspection

• Test Ignition Switch

  • Remove the steering column cover to access the ignition switch.
  • Use a multimeter to check continuity when the key is turned to the "Start" position.
  • If faulty, replace the ignition switch.

• Replace Ignition Switch (if necessary)

  • Disconnect wiring harness from the switch.
  • Remove screws holding the switch in place.
  • Install the new switch and reconnect wiring.