Q&A for How to Diagnose a Loss of Spark in Your Car Engine

Try replacing the harness that connects to the electronic ignition on the back of the engine.

It definitely can. You should check each cable for proper resistance. Put your voltmeter on 20k ohm position, it should read like 6k ohm, if it reads full resistance (1 to the left) then the wire is bad. Try to wiggle the wire you're testing, just in case that wire has internal breaking.

Look for a broken, loose, and/or corroded grounding wire. The negative terminal on the battery may also be loosely connected. Also check to make sure your gas isn't old.

The truck may not be pumping fuel into the cylinders because of being parked on a hill.

Sometimes a small crack in the distributor cap can allow moisture to get inside the housing.

If there is no spark coming from the coil, you may want to check the ballast resistor, which is a porcelain piece usually mounted near the firewall with either two or four prongs.

Check the spark plug for clogging, and also check the ECU, transformer coil, and HT wire. Charge the battery if it's a battery ignition system. Always check the ECU because it will show all electric-related problems (you'll need a device to check it).

Your problem could be the battery or the starter. You might want to have your alternator, battery, and starter all tested.

It could be anything from bad spark plugs to bad distributor, to a bad ignition coil, to faulty wiring. Test each one in that order.

Perhaps it is an alternator fault. The wiring to and from the alternator could drain the battery too, which would also stop the spark.

Could be a distributor issue or it could be a fuse to the distributor. If you don't have a distributor, then check your coil pack.

Yes, but most likely the engine would miss, run rough and throw a check engine code, for example P0300.