How to Troubleshoot a 1997 Ford Ranger Coil Pack

Open the hood on the Ranger and set the hood prop. Turn the multimeter dial to the Ohms setting. With the ignition off, disconnect the electrical connector from the ignition coil pack.

Insert the positive multimeter lead onto the B+ terminal on the coil pack, which is the farthest pin to the left of the coil pack electrical connector. Place the opposite multimeter lead on the next three pins. If the resistance on between B+ and coils 1 through 3 is not between 0.3 and 1.0 ohms, replace the ignition coil pack.

If the primary resistance from the B+ to coils 1 through 3 tests positive, then you need to test the secondary resistance between the spark plug wire towers. Do not remove more than two spark plug wires from the top of the coil pack at a time, so that you do not confuse the wires, and install them wrong.

Remove spark plug wires from towers 1 and 5, using the numbers stamped on the coil for guidance. Place the positive multimeter lead on the coil 1 pin on the electrical connector, which is the farthest pin to the right on the connector. Place the opposite lead on spark plug tower 1 then tower 5. If the resistance between the coil and either tower is not between 6,500 and 11,500 ohms, replace the coil pack. Install the spark plug wires if the test indicates these towers are good.

Remove spark plug wires 3 and 4 from the coil pack. Place the positive lead from the multimeter on coil 2 on the electrical connector, which is the second pin in from the left of the connector. Place the opposite lead on towers 3 and 4. If the reading is not between 6,500 and 11,500 ohms, replace the ignition coil. Install the spark plug wires if these two towers are good.

Remove spark plug wires 2 and 6 from the coil pack. Insert the positive lead from the multimeter on the coil 3 pin, which is the second pin in from the right on the connector. Place the other lead on towers 2 and 6. If the reading is not within the 6,500 to 11,500 specifications, replace the coil pack. Install the spark plug wires if the test proves that these towers are good.

Connect the electrical connector to the ignition coil pack if the coil pack tests are completed.

Open the hood on the Ranger and set the hood prop. Turn the multimeter dial to the Ohms setting. With the ignition off, disconnect the electrical connectors from the right and the left hand ignition coil packs.

Place the positive lead from the multimeter onto the B+ pin, in the electrical connector of one coil pack. The B+ pin is the center pin on both the right and left coils. Place the opposite lead on both outer pins individually. If the resistance measurement is not between 0.3 and 1.0 ohms, then replace the ignition coil pack.

Remove the spark plug wires from coil towers 1 and 2 on top of the ignition coil pack. Measure the resistance between the B+ coil pin and these two towers individually. If the measurement is not between 6,500 and 11,500 ohms, then replace the coil pack. Replace the spark plug wires if these two towers tested are within the specifications.

Remove the spark plug wires from coil towers 3 and 4. Test the towers the same way as the previous two towers. If the measurement is not within the provided specifications, replace the coil pack. Repeat steps 2 through 4 of this section to test the second coil pack, and replace that coil pack if necessary.

Place the electrical connectors back on both coil packs, if the test results prove that both coil packs are good. Install the negative battery cable, and tighten the hold-down nut until it is snug. Remove the memory saver from the Ranger.