1. The Basics - Check the Obvious First:
* Battery: Test the battery voltage. A weak battery can prevent the ignition system from functioning properly. Should be around 12.6V when not running.
* Battery Cables: Inspect the battery cables for corrosion, loose connections, or damage. Clean the terminals thoroughly if necessary.
* Fuses: Check the fuses related to the ignition system in the fuse box (both under the hood and inside the cab). Refer to your owner's manual for the correct fuse locations.
* Ignition Switch: Try turning the key all the way to "on" and listening for the fuel pump to prime. This confirms power is getting to at least part of the system. A malfunctioning ignition switch can interrupt power to the ignition system. If nothing happens, this is a prime suspect.
2. Ignition System Components (This is where it gets more involved):
* Ignition Coil: The ignition coil generates the high voltage needed for spark. You can test this with a multimeter or a spark tester. A visual inspection can sometimes reveal cracks or damage. A failing coil will often show weak or intermittent spark, not necessarily a complete absence.
* Ignition Control Module (ICM): This module controls the timing and firing of the ignition coil. Testing this requires more specialized equipment or knowledge. Symptoms of a bad ICM often include misfires or complete failure to start.
* Distributor (if equipped): Older vehicles might still have a distributor. Check the rotor and cap for wear, cracks, or corrosion. A bad cap or rotor will prevent spark. The distributor itself could also be failing internally (harder to test without specialized equipment).
* Crankshaft Position Sensor (CKP): This sensor tells the ICM the position of the crankshaft. Without a signal from this sensor, the ICM won't send a signal to fire the coil. Testing this requires a multimeter.
* Camshaft Position Sensor (CMP): This sensor is similar to the CKP but monitors the camshaft. It plays a role in fuel delivery and ignition timing. Again, a multimeter is required for testing.
3. Testing Procedures (Requires a multimeter and possibly a spark tester):
* Spark Tester: The easiest way to confirm if you have spark is to use an inline spark tester. Attach it to a spark plug wire and crank the engine. If you see a spark, the problem lies elsewhere. No spark points to a problem in the ignition system itself.
* Multimeter: You'll need a multimeter to test the voltage at various points in the ignition system to identify where the power is dropping off. This includes checking the coil power supply, sensor signals, and other wiring connections. You'll need a wiring diagram for your specific vehicle to identify test points.
4. Seeking Professional Help:
If you're not comfortable working with automotive electrical systems, it's best to take your F-150 to a qualified mechanic. Diagnosing ignition problems can be tricky and requires the right tools and experience.
Important Note: Always disconnect the negative battery cable before working on any electrical components to prevent injury. Consult a repair manual specific to your 1996 Ford F-150 5.8L for detailed wiring diagrams and testing procedures. These diagrams are crucial for proper diagnosis.
