Disconnect the battery negative terminal
Locate the starter motor solenoid
Inspect the solenoid, wiring, and terminals for damage or corrosion
Check the battery voltage with a multimeter
Reconnect the battery if needed for testing
Set the multimeter to DC volts
Measure voltage at the solenoid battery terminal
Have an assistant turn the key to the start position
Check for voltage at the solenoid trigger terminal when the key is turned
Listen for a click from the solenoid
Test continuity across the solenoid terminals
Test resistance of the solenoid coil
Perform a voltage drop test on the solenoid circuit
Bypass the solenoid with a jumper wire only if safe and appropriate
Check whether the starter motor engages when the solenoid is energized
Replace the solenoid if it fails voltage, continuity, or engagement tests