1. Simple Checks (Do these FIRST):
* Battery: Is the battery dead, loose, or corroded? Check the voltage with a multimeter. A low voltage might still crank the engine but prevent ignition.
* Battery Cables: Are the battery cables securely connected and free of corrosion? Clean the terminals if necessary.
* Ignition Switch: Is the ignition switch itself faulty? Try wiggling the key while in the "on" position. A failing switch might intermittently work or not work at all.
* Fuses and Relays: Check the fuses and relays related to the ignition system in the fuse box (under the hood and/or inside the vehicle). A blown fuse or failed relay is a common cause. Refer to your owner's manual for the correct fuse and relay locations.
* Neutral Safety Switch (Automatic Transmission): For automatic transmissions, this switch prevents starting unless the transmission is in park or neutral. Make sure it's working correctly.
2. Intermediate Checks (Require more technical knowledge or tools):
* Ignition Coil: This component transforms low voltage from the ignition system into the high voltage needed for the spark plugs. A faulty coil will prevent ignition. Testing requires a multimeter.
* Distributor (If equipped): Older 460s might have distributors. Problems with the distributor cap, rotor, or pickup coil can prevent proper ignition. Visual inspection and testing with a multimeter are needed.
* Spark Plugs and Wires: Worn or fouled spark plugs or damaged spark plug wires can prevent or weaken the spark, leading to no ignition. Inspect for damage or corrosion.
* Ignition Control Module (ICM): This electronic component controls the ignition timing and spark. A faulty ICM will prevent ignition and requires testing with a multimeter or diagnostic scanner.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational position; without a functioning CKP, the computer won't initiate ignition.
3. Advanced Checks (Likely require professional help):
* Wiring Harness Issues: Damaged or corroded wiring within the ignition system's wiring harness can cause intermittent or complete failure. This is difficult to diagnose without specific knowledge and tools.
* Computer (PCM): A faulty Powertrain Control Module (PCM) can prevent ignition, though this is less common. Diagnosis usually requires a professional scan tool.
* Security System (If Equipped): If the truck has an aftermarket or factory security system, a fault in the system might be preventing the engine from starting.
Troubleshooting Steps:
1. Start with the simplest checks (battery, cables, fuses, etc.). These are the quickest and easiest fixes.
2. Use a multimeter to test components like the battery, ignition coil, and distributor (if applicable). This will help pinpoint the problem.
3. If you're not comfortable working with automotive electrical systems, take it to a qualified mechanic. Incorrectly diagnosing or repairing electrical problems can lead to further damage.
Remember to always disconnect the negative battery terminal before working on any electrical components. Safety first!
