1. Check the obvious:
* Ignition Switch: Make sure your ignition switch is working correctly. Try turning the key to different positions and listen for the click of the ignition system engaging. A faulty switch won't send power to the rest of the system.
* Fuses and Relays: Check the fuses and relays related to the ignition system in your fuse box (under the hood usually, and possibly inside the cab). A blown fuse or failed relay will cut power. Consult your owner's manual for locations and ratings.
* Battery: Test your battery voltage. A weak battery might not provide enough power to fire the coil. Ideally, you should have at least 12.6 volts with the engine off.
2. Test for power and ground at the coil:
* Power to the coil: With the ignition key ON (but engine not cranking), use a test light or multimeter to check for 12V power at the positive (+) terminal of the coil. If you don't have power here, trace the wire back towards the ignition switch. A broken wire, bad connection, or faulty ignition control module (ICM) is possible.
* Ground at the coil: Check the negative (-) terminal of the coil for a good ground connection. A poor ground will prevent the coil from working correctly. Clean the terminal and ensure it has good metal-to-metal contact with the engine block.
3. Inspect the ignition control module (ICM):
* The ICM is a common failure point in these older Ford trucks. It's a small electronic box often mounted near the distributor. It controls the coil's firing. Visually inspect it for any obvious damage. While testing power to the coil helps, a faulty ICM can fail to send the signal, even with power present. Replacing this is often necessary with similar symptoms. This can sometimes be tested with an oscilloscope, but most backyard mechanics won't have one.
4. Distributor issues (less likely given your description):
* Pick-up coil in the distributor: While you say *no fire from the coil to the distributor*, a faulty pick-up coil (the sensor that tells the ICM when to fire) *inside* the distributor could be preventing the signal from reaching the ICM. This is less likely if you're sure you have no power from the coil, however.
* Rotor and cap: Inspect the distributor cap and rotor for cracks, corrosion, or worn-out contact points. Replace if necessary. A bad cap and rotor won't directly cause no spark to the coil, but it will prevent any spark from reaching the plugs even with a properly working coil and ICM.
Troubleshooting Steps:
1. Start with the simplest checks (battery, fuses, and ignition switch).
2. Then check power and ground at the coil. This is the most important step.
3. If power and ground are good at the coil, suspect the ICM.
4. Only after addressing the above, start inspecting the distributor components.
Important Note: If you are not comfortable working with automotive electrical systems, it's best to take your truck to a qualified mechanic. Improperly working on the ignition system can be dangerous.
