Ignition Coils (4.0L)

On 4.0L, a one-piece coil rail assembly is used. Coil rail assembly is located on top of engine, right of valve cover. Coil rail includes 3 coils, which are connected to spark plugs through cables that are integral to coil rail assembly. One electrical connector, located at rear of coil rail, is used for all 3 coils. Individual coils cannot be replaced separately. If any coils are defective, coils and coil rail must be replaced as an assembly. Battery voltage is supplied to all 3 coils through ASD relay. PCM operates coils and adjusts ignition timing by controlling coil ground circuits.