Ford Ignition Coil Removal Procedure With Diagrams

Ford F-350 Ignition Coil Replacement procedure

TESTING

Ignition Coil Test

The ignition coil must be diagnosed separately from the rest of the ignition system.

1. Primary resistance is measured between the two primary (low voltage) coil terminals, with the coil connector disconnected and the ignition switch off. Primary resistance should be 0.3-1.0 ohms.
2. On Dura Spark ignitions, the secondary resistance is measured between the BATT and high voltage (secondary) terminals of the ignition coil with the ignition OFF , and the wiring from the coil disconnected. Secondary resistance must be 8,000-11,500 ohms.
3. If resistance tests are okay, but the coil is still suspected, test the coil on a coil tester by following the test equipment manufacturer's instructions for a standard coil. If the reading differs from the original test, check for a defective wiring harness.

Ignition Coil Primary Circuit Switching

1. Insert a small straight pin in the wire which runs from the coil negative (-) terminal to the TFI module, about 1 in. (25mm) from the module.

WARNING

The pin must not touch ground!

2. Connect a 12 VDC test lamp between the straight pin and an engine ground.
3. Crank the engine, noting the operation of the test lamp. If the test lamp flashes, proceed to the next test. If the test lamp lights but does not flash, proceed to the Wiring Harness test. If the test lamp does not light at all, proceed to the Primary Circuit Continuity test.

Ignition Coil Resistance

Refer to the General Testing for an explanation of the resistance tests. Replace the ignition coil if the resistance is out of the specification range.

Ignition Coil Secondary Voltage

1. Disconnect the secondary (high voltage) coil wire from the distributor cap and install a spark tester between the coil wire and ground.
2. Crank the engine. A good, strong spark should be noted at the spark tester. If spark is noted, but the engine will not start, check the spark plugs, spark plug wiring, and fuel system. If there is no spark at the tester: Check the ignition coil secondary wire resistance; it should be no more than 5,000 ohms per foot. Inspect the ignition coil for damage and/or carbon tracking. With the distributor cap removed, verify that the distributor shaft turns with the engine; if it does not, repair the engine as required. If the fault was not found proceed to the Ignition Coil Primary Voltage test.

Ignition Coil Primary Voltage

1. Attach the negative lead of a voltmeter to the distributor base.
2. Turn the ignition switch ON and connect the positive voltmeter lead to the negative (-) ignition coil terminal. Note the voltage reading and turn the ignition OFF . If the voltmeter reading is less than 90 percent of the available battery voltage, inspect the wiring between the ignition module and the negative (-) coil terminal, then proceed to the Ignition Coil Supply Voltage test.

Ignition Coil Supply Voltage

1. Attach the negative lead of a voltmeter to the distributor base.
2. Turn the ignition switch ON and connect the positive voltmeter lead to the positive (+) ignition coil terminal. Note the voltage reading then turn the ignition OFF . If the voltage reading is at least 90 percent of the battery voltage, yet the engine will still not run; first, check the ignition coil connector and terminals for corrosion, dirt, and/or damage; second, replace the ignition switch if the connectors and terminal are okay.
3. Connect any remaining wiring.

REMOVAL & INSTALLATION

Carbureted Engines

1. Disconnect the battery ground.
2. Disconnect the two small and one large wires from the coil.
3. Disconnect the condenser connector from the coil, if equipped.
4. Unbolt and remove the coil.
5. Installation is the reverse of removal.

Fuel Injected Engines

See Figures 1, 2, 3 and 4

Fig. Fig. 1: Disengage the high tension wire by pulling on the connector boot-fuel injected engines

Fig. Fig. 2: Separate the wiring harness connection at the coil

Fig. Fig. 3: Unscrew the coil from its bracket mount

Fig. Fig. 4: Remove the coil from the engine

1. Pulling on the connector boot, disconnect the high tension lead at the coil.
2. Disconnect the wiring at the ignition coil.
3. Remove the ignition coil-to-bracket attaching screws, then remove the coil.

To install:

4. Install the coil, tightening the screws to 25-35 inch lbs. (2.8-4.0 Nm).
5. Connect the ignition coil wiring harness and the high tension lead.