The 1969 Ford F100 uses a basic mechanical electrical system for starting the vehicle. The wiring runs from the battery to the starter relay, also called a solenoid, and then to the various components of the vehicle. The starter relay simply moves electricity from the battery to the starter when the key is engaged. The relay also provides electricity for several other components, such as the lights and radio. Issues with the unit occur with normal use and age. You can diagnose a damaged starter relay with a multimeter.
Connect a jumper wire (small strip of wire) from the battery post on the starter relay to the starter post. The battery post is the left-hand bolt that you can trace directly to the battery. The starter post is the right-hand post. Your vehicle should attempt to start. Remove the jumper wire.
Attempt to start the vehicle. Replace the starter relay if nothing happens.
Connect the red wire from the multimeter to the starter post on the relay. Turn the multimeter to read DC amps. Connect the black wire to a ground point (an unpainted bolt or the negative post on the battery). Turn the key to on. You should notice activity on the multimeter. Check for loose connections on your ignition switch. If there are no loose connections, replace the starter relay.
