Jeep

The ASD relay and fuel pump should only run for one second after turning on the ignition switch. They turn on again during engine rotation, (cranking or running). The Engine Computer knows to turn them on by the pulses it gets from the crankshaft position sensor and camshaft position sensor.

If it's connected and has a ground, just for that first one second, then again during cranking. If it doesn't run for that one second, check the fuel pump relay, ASD relay, and pump's ground wire. If it DOES run for one second but not during cranking, you won't have spark either. Have you checked for spark? If it's missing, check the cam and crank sensors.

Holler back when you know if there's spark or not.

Find the feed wire to the ignition coil, any injector, or either small wire on the back of the alternator and measure the voltage on it. You should see 0 volts at first, 12 volts for one second when the ignition switch is turned on, it'll go back to 0 volts, then the 12 volts must come back during cranking. If it doesn't come back during cranking, suspect the crankshaft position sensor or the camshaft position sensor.

Sorry it took so long to get back to you. Internet provider was down again yesterday for the entire day.

Sounds like you have your voltmeter grounded to the battery positive post. It should be on the negative post.

Pull out the ASD relay. If you still have voltage to the coil and injectors you'll have to follow the wires back to see where it's coming from.

Electronics is actually very easy to understand, ... IF you are the type of person who can learn by visualizing things you can't see. Most automotive students don't learn that way. They are the type of people who learn best by touching, taking apart, manipulating, and seeing how parts interact. Can't do that with electricity, but you've played with water and a garden hose. In my Auto Electrical classes I compared everything electrical to water flow in a pipe. My students had real good success and have a dandy reputation in the community. Don't feel stupid. You probably learned electronics from someone good at visualizing and they think everyone learns the same way.

The ASD relay socket should have 12 volts on two terminals all the time. One supplies one side of the coil and one supplies the current that will go through the contacts. The Engine Computer grounds the other coil terminal, then the magnetic field pulls the arm down to connect the contacts. Current flows through the contacts to the ignition coil(s), injectors, alternator field, oxygen sensor heaters, and possibly the fuel pump or pump relay.

With the relay removed, if you have voltage to any of those parts, you have your meter probe grounded to the battery positive post. It must be grounded to the negative post. If you still read voltage there, something is wired wrong and is bypassing the relay.

If you find 0 volts, plug the relay back in. If you feel it click, something is grounding the coil. That could be the computer, although that type of failure is real uncommon. Again, I'd look for something wired wrong. If you unplug the Engine Computer and the relay turns off, the computer would have to be suspect.