General information
Engine electrical systems include all charging, starting and heating components. Because of their engine-related functions, these components are considered separately from electrical devices on the body, such as lighting, signaling, etc. (which are discussed in Chapter 12).
The electrical system is negatively grounded and operates at 12V. The battery is either low-maintenance or completely sealed and is charged by a belt-driven alternator from the crankshaft pulley. All later models have a single battery, some earlier models have two batteries.
A pre-engaged starter incorporates an electromagnetic starting relay that causes the pinion gear to engage the flywheel ring gear before the starter engages. Once the engine has started, the one-way overrunning clutch prevents the starter armature from rotating away from the engine until the pinion is disengaged from the flywheel.
Some models may have a flare-type preheating system. The spark plug ignites a small amount of fuel in the intake manifold, which is drawn into the combustion chambers to aid cold starting.
Further more detailed descriptions of the various systems and their components are given in the relevant sections of this chapter. Repair operations are also described and the procedure for replacing the components you are interested in is provided.
Precautionary measures
Special care must be taken when working on the electrical system to avoid damage to semiconductor devices (diodes and transistors) or electric shock.
In addition to the precautions given at the beginning of this manual in the "Safety First" section, observe the following precautions when working with electrical equipment.
Remove rings, watches, etc. when working on the electrical system. Even when the battery is disconnected, static charge may be present, causing a current to flow when the terminal contacts grounded metal. This may result in electric shock and burns.
Do not reverse the battery terminals! Otherwise, components containing semiconductor circuits or the alternator may burn out.
When starting the engine from a booster battery, always connect positive to positive and negative to negative (see section "Jump starting the engine").
Please also follow this rule when using the charger.
Never disconnect the battery terminals, alternator terminals, any wires or instrumentation while the engine is running.
Do not allow the engine to turn the alternator if the alternator is disconnected from the load.
Never "test" an alternator by sparking the output conductor to ground.
Do not use the generator's built-in ohmmeter to test for continuity.
When working on the electrical system, be sure to disconnect the negative battery cable.
Before using electric arc welding equipment on a vehicle, disconnect the alternator and battery to protect them from possible damage.
The latest Ford models come standard with a radio that has an electronic theft lock. When the current from the electrical source is interrupted, the radio automatically locks. Even if this source is immediately connected, the radio will not operate until the correct security code is entered. Therefore, if you do not know the correct code, do not disconnect the negative battery terminal or remove the radio. Please refer to the section "Radio blocking system in case of theft" at the beginning of the guide for detailed information.
(The material was copied from an information website: FordBook.ru)