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How to Troubleshoot the Ignition System in a Dodge Ram

by ContributorUpdated November 07, 2017

Items you will need

  • Screwdriver or rod

  • Ohmmeter

How to Troubleshoot the Ignition System in a Dodge Ram. The best way to troubleshoot your Dodge Ram's ignition system depends on the type of system you have. There's plenty you can do on a distributor system, but a distributorless system restricts you to test only the spark plug condition and ignition coil resistance.

Distributor System

Remove the spark plug wires one at a time from the distributor while the engine runs. There is a problem with the spark plug, wire or distributor terminal if the engine performance doesn't drop.

Test the spark plugs. Remove each plug (one at a time) from its cylinder and ground it on the engine. Crank the engine and look for a spark at the plug.

Replace the plug in the boot with a screwdriver or metal rod if no spark appeared. Hold the screwdriver/rod a quarter inch from the engine and crank it again. Replace the spark plug if a spark jumps now.

Inspect the condition of the plug wires. Replace the wire if it is burned or cracked or has insulation damage. Test the resistance with an ohmmeter; it shouldn't exceed 12,000 ohms/foot.

Check the distributor cap's condition. Look for cracks in the cap, terminal corrosion, internal contact erosion, carbon paths or other faults.

Distributerless System With an 8.0L Engine

Verify the spark plugs are clean of deposits or wear (they can be cleaned with a stiff brush). Make sure the electrodes are perfectly flat with the ground electrode parallel to the center electrode.

Prepare the ignition coils for testing. Disconnect the negative battery cable, the spark plug leads and the primary wiring on from the coil packs.

Use an ohmmeter to check the resistance across each pair of spark plug high tension terminals that are back-to-back with each other. The resistance should be 11,000 to 15,000 ohms.

Go to the connectors on the side of the coil pack. Connect the ohmmeter to the B+ terminal on each connector and each coil terminal individually. The resistance now should be 0.53 to 0.65 ohms.

Replace the coil pack if resistance doesn't completely meet specification.

Distributorless System With Other Engines

Look over the spark plugs the same was as with an 8.0L engine.

Disconnect the negative battery cable and remove the ignition coil from the engine.

Probe the low-tension terminals on the coil to check the primary winding resistance. It should be 0.6 to 0.9 ohms.

Measure the secondary winding resistance across the spark plug lead and a low-tension terminal. It should be 6,000 to 9,000 ohms. Replace a coil not within specification.


The B+ terminal is the second from the right four-terminal connector or the middle one on the three-terminal connector.


Insulate yourself with rubber gloves and shoes before handling the spark plug wires. Don't remove a wire from a running engine for more than a few seconds.

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