Mercury 1L2Z-12029-AA Coil Assembly - Ignition

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Disconnect the cable(s) from the negative battery terminal(s). Disconnect the ignition coil electrical connector(s) from each individual coil. Use tape and mark each electrical connector with the correct cylinder number to prevent mix-ups during reassembly, if necessary. Remove the bolt securing the ignition coil, then pull the coil from the cylinder head. Note: 2006 and later models have individual coils for each spark plug. The coils are mounted to the top of the valve covers. Installation is the reverse of the removal procedure with the following additions: Prior to installing the coil, coat the entire interior of the rubber boot with silicone dielectric compound. Connect each coil electrical connector to its correct coil and make sure they are tight and secure.

First of all, the coils should be wiped clean with a damp cloth and left to dry completely. Look for any cracks, damage or carbon tracking on each coil. Be certain that the coil fits tightly on the spark plug. Replace the coil if it is damaged. To get to the spark plugs, you have to take out the ignition coil, disconnect the electrical connector and remove the coil retaining screw. Pull straight up and out to remove the coil.

After removing the old coil in the COP system, inspect the spark plug and check the coil harness connector terminals. Then, replace the coil and reconnect the harness.

To check the electronic integrated (El) ignition system, start by disconnecting the electrical connector(s) from the coil with the ignition off. Then, use an ohmmeter to measure the resistance between the coil positive (+) terminal and each negative (-) terminal. The resistance should be the same for each check and should match the specifications listed. Next, connect the ohmmeter between the secondary terminals of each coil pack, which are paired according to the companion cylinders. Again, the resistance should match the specifications. If the resistance is not correct, the coil should be replaced.

Clean the coil packs with a dampened cloth and dry them thoroughly. Then, inspect each coil pack for cracks, damage, and carbon tracking.

Use an ohmmeter to check the coil primary resistance and compare it to the specifications. Do the same for the coil secondary resistance. If the resistances are not as specified, replace the coil. Keep all coil terminals and wire leads clean, tight, and dry.

After removing the old coil in the COP system, inspect the spark plug and check the coil harness connector terminals. Then, replace the coil and reconnect the harness.