Engine electrical systems Ford F150

General information

Ignition system

1. The ignition system consists of ignition coils, spark plugs, the Camshaft Position (CMP) sensor, the Crankshaft Position (CKP) sensor, the knock sensor, and the Powertrain Control Module (PCM).

2. The CKP, CMP and knock sensors are information sensors used by the PCM to control ignition timing and other engine operating parameters. The PCM also uses a number of other information sensors to make decisions regarding the correct ignition timing. These other sensors include the Throttle Position (TP) sensor, the Engine Coolant Temperature (ECT) sensor, the Mass Air Flow (MAF) sensor, the Intake Air Temperature (IAT) sensor, the Vehicle Speed Sensor (VSS) and the transmission gear position sensor or Transmission Range (TR) switch. For more information on these and other sensors, refer to Emissions and engine control systems.

Charging system

3. The charging system includes the alternator (with an integral voltage regulator), the Powertrain Control Module (PCM), the Body Control Module (BCM), a charge indicator light on the dash, the battery, a fuse or fusible link and the wiring connecting all of these components. The charging system supplies electrical power for the ignition system, the lights, the radio, etc. The alternator is driven by a drivebelt.

Starting system

4. The starting system consists of the battery, the ignition switch, the starter relay, the Powertrain Control Module (PCM), the Body Control Module (BCM), the Transmission Range (TR) switch, the starter motor and solenoid assembly, and the wiring connecting all of these components.


5. Always observe the following precautions when working on the electrical system:

  1. Be extremely careful when servicing engine electrical components. They are easily damaged if checked, connected or handled improperly.
  2. Never leave the ignition switched on for long periods of time when the engine is not running.
  3. Never disconnect the battery cables while the engine is running.
  4. Maintain correct polarity when connecting battery cables from another vehicle during jump starting — see the Booster battery (jump) starting at the beginning of this manual.
  5. Always disconnect the cable from the negative battery terminal before working on the electrical system, but read the battery disconnection procedure first (see Battery – disconnection and reconnection).

6. It’s also a good idea to review the safety-related information regarding the engine electrical systems located in the Safety first! Section at the front of this manual before beginning any operation included in this chapter.

Battery – disconnection and reconnection
Battery and battery tray – removal and installation
Battery cables and sensors – replacement
Ignition coils – removal and installation
Alternator – removal and installation
Starter motor – removal and installation

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