Ford Ranger Maintaince And Repair Manual page 190

Ignition Coil Primary Resistance Test
1. Turn the ignition switch off, then disconnect the ignition coil connector.
2. Check for dirt, corrosion or damage.
3. Use an ohmmeter to measure the resistance from the positive (+) to negative (−) terminals of the
ignition coil.
4. If the reading is between 0.3−1.0 ohms the ignition coil is OK; continue on to the Ignition Coil
Secondary Resistance Test. If the reading is less than 0.3 ohms or greater than 1.0 ohms , replace the
ignition coil.
Ignition Coil Secondary Resistance Test
1. Use an ohmmeter to measure the resistance between the negative (−) terminal to the high voltage
terminal of the ignition coil.
2. If the reading is between 6,500−11,500 ohms, the ignition coil is OK. If the reading is less than 6500
ohms or more than 11,500 ohms , replace the ignition coil.
TESTING
HOW TO USE THIS BOOK
Ignition coil supply voltage test 8 chart
Click to enlarge
Ignition coil primary resistance test
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