* Ignition Coil: This is a common culprit. A faulty coil won't produce the high voltage needed to fire the spark plugs. Testing the coil's resistance with a multimeter is necessary.
* Ignition Module (Electronic Ignition Control Unit - ECM): The module controls the ignition timing and spark. A failed module will prevent spark. These are often difficult to test without specialized equipment.
* Ignition Switch: If the switch is bad, it won't send power to the rest of the ignition system.
* Distributor Cap and Rotor: These components distribute the high voltage to the spark plugs. Cracks, corrosion, or worn contacts will prevent spark. A visual inspection is crucial.
* Worn or Damaged Spark Plug Wires: These wires carry the high voltage to the spark plugs. Cracks, fraying, or poor connections will disrupt the spark.
* Spark Plugs: Fouled or damaged spark plugs won't fire. Inspection and replacement may be needed.
* Pick-up Coil (in the distributor): This component senses the position of the rotor and signals the ignition module. A faulty pick-up coil will result in no spark.
* Wiring Issues: A broken or corroded wire anywhere in the ignition circuit can interrupt the spark. A careful visual inspection of all wiring is important.
* Crankshaft Position Sensor (CPS) (if equipped): Some 1984 models might have a CPS. A faulty sensor won't allow the ignition system to function.
To troubleshoot, start with the simplest checks (visual inspection of wires, cap, rotor, plugs) and then progress to more complex components (coil, module) using a multimeter or other testing equipment. A wiring diagram specific to your year and model truck will be extremely helpful. A repair manual is highly recommended for this type of troubleshooting.
