15-42
(13) PTC heater control
A. Overview
The supplementary electrical heater is installed in DI engine equipped vehicle as a basic equipment. The
PTC system is operated according to two temperature values measured at the coolant temperature
sensor and HFM sensor. This device is mounted in the heater air outlet and increase the temperature of
air to the passenger compartment. Because PTC system is heated by electrical power, high capacity
alternator is required. PTC does not operate during engine cranking, while the battery voltage is lower
than 11 V or during preheating process of glow plugs.
B. Components
HFM (intake air
temperature)
Coolant temperature
sensor
PTC relay 1
D20DTR ECU
PTC relay 2
PTC fuse 1, 2, 3, 40A
PTC heater
PTC Fuse and Relay
08-51452-01
1. CHARGING SYSTEM OPERATION
Alternators use a new type of regulator that incorpo-rates a diode trio. A Delta stator, a rectifier
bridge, and a rotor with slip rings and brushes are electrically similar to earlier alternators.
A conventional pulley and fan are used. There is no test hole.
1) Charging Time Required
The time required to charge a battery will vary depending upon the following factors:
Size of Battery ▶
A Completely discharged large heavy-duty battery required more than twice the
recharging time as a completely discharged small passenger car battery. -
Temperature ▶
A longer time will be needed to charge any battery at -18°C (0°F) than at 27°C (80°F).
When a fast charger is connected to a cold battery, the current accepted by the battery
will be very low at first. The battery will accept a higher current rate as the battery warms. -
Charger Capacity ▶
A charger which can supply only 5 amperes will require a much longer charging period
than a charger that can supply 30 amperes or more. -
State-of-Charge ▶
A completely discharged battery requires more than twice as much charge as a onehalf
charged battery. Because the electrolyte is nearly pure water and a poor conductor in a
completely discharged battery, the current accepted by the battery is very low at first.
Later, as the charging current causes the electrolyte acid content to increase, the charging
current will likewise increase. -
2. STARTING SYSTEM OPERATION
The engine electrical system includes the battery, the ignition, the starter, the alternator, and all
the related wiring. Diagnostic tables will aid in troubleshooting system faults. When a fault is
traced to a particular component, refer to that component section of the service manual. The
starting system circuit consists of the battery, the starter motor, the ignition switch, and all the
related electrical wiring. All of these components are connected electrically.
